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  • How can a code editor effectively hint at code nesting level - without using indentation?

    - by pgfearo
    I've written an XML text editor that provides 2 view options for the same XML text, one indented (virtually), the other left-justified. The motivation for the left-justified view is to help users 'see' the whitespace characters they're using for indentation of plain-text or XPath code without interference from indentation that is an automated side-effect of the XML context. I want to provide visual clues (in the non-editable part of the editor) for the left-justified mode that will help the user, but without getting too elaborate. I tried just using connecting lines, but that seemed too busy. The best I've come up with so far is shown in a mocked up screenshot of the editor below, but I'm seeking better/simpler alternatives (that don't require too much code). [Edit] Taking the heatmap idea (from: @jimp) I get this and 3 alternatives - labelled a, b and c: The following section describes the accepted answer as a proposal, bringing together ideas from a number of other answers and comments. As this question is now community wiki, please feel free to update this. NestView The name for this idea which provides a visual method to improve the readability of nested code without using indentation. Contour Lines The name for the differently shaded lines within the NestView The image above shows the NestView used to help visualise an XML snippet. Though XML is used for this illustration, any other code syntax that uses nesting could have been used for this illustration. An Overview: The contour lines are shaded (as in a heatmap) to convey nesting level The contour lines are angled to show when a nesting level is being either opened or closed. A contour line links the start of a nesting level to the corresponding end. The combined width of contour lines give a visual impression of nesting level, in addition to the heatmap. The width of the NestView may be manually resizable, but should not change as the code changes. Contour lines can either be compressed or truncated to keep acheive this. Blank lines are sometimes used code to break up text into more digestable chunks. Such lines could trigger special behaviour in the NestView. For example the heatmap could be reset or a background color contour line used, or both. One or more contour lines associated with the currently selected code can be highlighted. The contour line associated with the selected code level would be emphasized the most, but other contour lines could also 'light up' in addition to help highlight the containing nested group Different behaviors (such as code folding or code selection) can be associated with clicking/double-clicking on a Contour Line. Different parts of a contour line (leading, middle or trailing edge) may have different dynamic behaviors associated. Tooltips can be shown on a mouse hover event over a contour line The NestView is updated continously as the code is edited. Where nesting is not well-balanced assumptions can be made where the nesting level should end, but the associated temporary contour lines must be highlighted in some way as a warning. Drag and drop behaviors of Contour Lines can be supported. Behaviour may vary according to the part of the contour line being dragged. Features commonly found in the left margin such as line numbering and colour highlighting for errors and change state could overlay the NestView. Additional Functionality The proposal addresses a range of additional issues - many are outside the scope of the original question, but a useful side-effect. Visually linking the start and end of a nested region The contour lines connect the start and end of each nested level Highlighting the context of the currently selected line As code is selected, the associated nest-level in the NestView can be highlighted Differentiating between code regions at the same nesting level In the case of XML different hues could be used for different namespaces. Programming languages (such as c#) support named regions that could be used in a similar way. Dividing areas within a nesting area into different visual blocks Extra lines are often inserted into code to aid readability. Such empty lines could be used to reset the saturation level of the NestView's contour lines. Multi-Column Code View Code without indentation makes the use of a multi-column view more effective because word-wrap or horizontal scrolling is less likely to be required. In this view, once code has reach the bottom of one column, it flows into the next one: Usage beyond merely providing a visual aid As proposed in the overview, the NestView could provide a range of editing and selection features which would be broadly in line with what is expected from a TreeView control. The key difference is that a typical TreeView node has 2 parts: an expander and the node icon. A NestView contour line can have as many as 3 parts: an opener (sloping), a connector (vertical) and a close (sloping). On Indentation The NestView presented alongside non-indented code complements, but is unlikely to replace, the conventional indented code view. It's likely that any solutions adopting a NestView, will provide a method to switch seamlessly between indented and non-indented code views without affecting any of the code text itself - including whitespace characters. One technique for the indented view would be 'Virtual Formatting' - where a dynamic left-margin is used in lieu of tab or space characters. The same nesting-level data used to dynamically render the NestView could also used for the more conventional-looking indented view. Printing Indentation will be important for the readability of printed code. Here, the absence of tab/space characters and a dynamic left-margin means that the text can wrap at the right-margin and still maintain the integrity of the indented view. Line numbers can be used as visual markers that indicate where code is word-wrapped and also the exact position of indentation: Screen Real-Estate: Flat Vs Indented Addressing the question of whether the NestView uses up valuable screen real-estate: Contour lines work well with a width the same as the code editor's character width. A NestView width of 12 character widths can therefore accommodate 12 levels of nesting before contour lines are truncated/compressed. If an indented view uses 3 character-widths for each nesting level then space is saved until nesting reaches 4 levels of nesting, after this nesting level the flat view has a space-saving advantage that increases with each nesting level. Note: A minimum indentation of 4 character widths is often recommended for code, however XML often manages with less. Also, Virtual Formatting permits less indentation to be used because there's no risk of alignment issues A comparison of the 2 views is shown below: Based on the above, its probably fair to conclude that view style choice will be based on factors other than screen real-estate. The one exception is where screen space is at a premium, for example on a Netbook/Tablet or when multiple code windows are open. In these cases, the resizable NestView would seem to be a clear winner. Use Cases Examples of real-world examples where NestView may be a useful option: Where screen real-estate is at a premium a. On devices such as tablets, notepads and smartphones b. When showing code on websites c. When multiple code windows need to be visible on the desktop simultaneously Where consistent whitespace indentation of text within code is a priority For reviewing deeply nested code. For example where sub-languages (e.g. Linq in C# or XPath in XSLT) might cause high levels of nesting. Accessibility Resizing and color options must be provided to aid those with visual impairments, and also to suit environmental conditions and personal preferences: Compatability of edited code with other systems A solution incorporating a NestView option should ideally be capable of stripping leading tab and space characters (identified as only having a formatting role) from imported code. Then, once stripped, the code could be rendered neatly in both the left-justified and indented views without change. For many users relying on systems such as merging and diff tools that are not whitespace-aware this will be a major concern (if not a complete show-stopper). Other Works: Visualisation of Overlapping Markup Published research by Wendell Piez, dated from 2004, addresses the issue of the visualisation of overlapping markup, specifically LMNL. This includes SVG graphics with significant similarities to the NestView proposal, as such, they are acknowledged here. The visual differences are clear in the images (below), the key functional distinction is that NestView is intended only for well-nested XML or code, whereas Wendell Piez's graphics are designed to represent overlapped nesting. The graphics above were reproduced - with kind permission - from http://www.piez.org Sources: Towards Hermenutic Markup Half-steps toward LMNL

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  • How should code reviews be Carried Out?

    - by Graviton
    My previous question has to do with how to advance code reviews among the developers. Here I am interested in how a code review session should be carried out, so that both the reviewer and reviewed are feeling comfortable with it. I have done some code reviews before and the experience has been very unpleasant. My previous manager would come to us --on an ad hoc basis-- and tell us to explain our code to him. Since he wasn't very familiar with the code base, whenever he would ask me to explain my code, I'd find myself spending a huge amount of time explaining the most basic structure of my code. As a result, each review would last much too long, and the process would leave both of us exhausted. Once I was done explaining my work, he would continue by raising issues with it. Most of the issues he raised were cosmetic in nature ( e.g, don't use region for this code block, change the variable name from xxx to yyy even though the later makes even less sense, and so on). After trying this process for few rounds, we found the review session didn't derive much benefits for either of us, and we stopped. How would you go about making each code review a natural, enjoyable, thought stimulating, bug-fixing and mutual-learning experience? Also, how frequently you do your code reviews - as soon as the code is checked in? Do you allocate a fixed time every week to do this? What are the guidelines that you follow during your code reviews?

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  • What are the standard directory layouts for source code?

    - by splattered bits
    I'm in the process of proposing a new standard directory layout that will be used across all the projects in our organization. Projects can have compiled source code, setup scripts, build scripts, third-party libraries, database scripts, resources, web services, web sites, etc. This is partly inspired by discovering Maven's standard layout. Are there any other standard layouts that are generally accepted in the industry?

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  • Unit-testing code that relies on untestable 3rd party code

    - by DudeOnRock
    Sometimes, especially when working with third party code, I write unit-test specific code in my production code. This happens when third party code uses singletons, relies on constants, accesses the file-system/a resource I don't want to access in a test situation, or overuses inheritance. The form my unit-test specific code takes is usually the following: if (accessing or importing a certain resource fails) I assume this is a test case and load a mock object Is this poor form, and if it is, what is normally done when writing tests for code that uses untestable third party code?

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  • What is reading source on an ebook reader like?

    - by Daniel Straight
    There are a few open source projects I would really like to read through the code of to understand better / improve on. The problem is, for me, reading for a long time on the computer screen is tedious. I would love to be able to read code while lounging around and on a screen that was better on my eyes. Has anyone ever tried reading code on an ebook reader? It seems like the e-ink would make it easy on the eyes, plus it would be portable, plus it wouldn't kill any trees. In other words, it sounds perfect, but before I drop a couple benjamins on an ebook reader, I'd like to hear if anyone else has tried this and how it went. It seems Scott Hanselman discussed using the Kindle to read code, but I wouldn't necessarily want a Kindle. Has anyone had a positive experience with some other device? I realize this is not directly about programming, but it relates directly to my ability to improve my skills. I think if a good portable reading device for code exists, it could help a lot of programmers.

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  • Should maven generate jaxb java code or just use java code from source control?

    - by Peter Turner
    We're trying to plan how to mash together a build server for our shiny new java backend. We use a lot of jaxb XSD code generation and I was getting into a heated argument with whoever cared that the build server should delete jaxb created structures that were checked in generate the code from XSD's use code generated from those XSD's Everyone else thought that it made more sense to just use the code they checked in (we check in the code generated from the XSD because Eclipse pretty much forces you to do this as far as I can tell). My only stale argument is in my reading of the Joel test is that making the build in one step means generating from the source code and the source code is not the java source, but the XSD's because if you're messing around with the generated code you're gonna get pinched eventually. So, given that we all agree (you may not agree) we should probably be checking in our generate java files, should we use them to generate our code or should we generate it using the XSD's?

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  • Software for "High-level" source code (C++) Management

    - by Korchkidu
    after a lot of small-medium projects, I have a lot of libraries and test programs here and there. Also, I must admit that some of the "best practices" I learnt are not that "good" IMHO. In particular, documenting your code and making a "high-level" documentation is not useful in practice: High-level documentation are not maintain up to date = I prefer to read the source code directly; Browsing generated developer documentation is a pain (IMHO) = I prefer to read the source code directly. For that reason, I am looking for a tool who could help me organize all my source code directories in a more "readable manner". What I need is a tool which: Maintains an UML diagram from C++ source code. I don't need source code generation from UML; USE CASE: I am in this super-tool, I notice a design issue, I change the source code, when I get back, the UML diagram is updated; Maintains easily browsable call graphs; Lists references to methods, variables, etc. For example, when I want to see where/when a method is called; Helps writing pseudo-code from C++; Embeds a nice C++ source code browser; Is Open Source would be great; Works at least on Win7. The focus of this tool should be to browse source code to understand what's going on. For example, when you have a newcomer and you need him to go through source code. Do you know any great tool? Thanks in advance. PS: please do not answer doxygen (great tool however).

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  • When is calculating or variable-reading faster?

    - by Andreas Hornig
    hi, to be honest, I don't really know what the "small green men" in my cpu and compiler do, so I sometimes would like to know :). Currently I would like to know what's faster, so that I can design my code in a more efficient way. So for example I want to calclate something at different points in my sourcecode, when will it be faster to calculate it once and store it in a variable that's read and used for the next points it's needed and when is it faster to calculate it everytime? I think it's depending on how "complex" and "long" the calculation is and how fast then cache is, where variables are stored, but I don't have any clue what's faster :). Thanks for any reply to my tiny but important question! Andreas PS: perhaps it's important to know that I code in JAVA, but it's more a genral question.

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  • Design Code Outside of an IDE (C#)?

    - by ryanzec
    Does anyone design code outside of an IDE? I think that code design is great and all but the only place I find myself actually design code (besides in my head) is in the IDE itself. I generally think about it a little before hand but when I go to type it out, it is always in the IDE; no UML or anything like that. Now I think having UML of your code is really good because you are able to see a lot more of the code on one screen however the issue I have is that once I type it in UML, I then have to type the actual code and that is just a big duplicate for me. For those who work with C# and design code outside of Visual Studio (or at least outside Visual Studio's text editor), what tools do you use? Do those tools allow you to convert your design to actual skeleton code? It is also possible to convert code to the design (when you update the code and need an updated UML diagram or whatnot)?

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  • Freelancing - Share the source code?

    - by Tec
    I have developed a couple of form based windows application in vb.net for a client and they all work well and he paid me through a freelance site. I have handed over the executable and the setup to the client and all was well. Now the client wants the source code for the application. Is there a general practice on sharing the source code with the client? Please note - the client never mentioned he needs the source code and he is now asking for it after a week after the app was completed and he made the payment. I don't mind sharing the source code, but I am not sure if I should. This probably means the client would not hire me again and the bigger question is the source code really his property? This question may have been asked a few times, but I cannot still draw a conclusion on what is right. update To answer some of the questions: The source code was not mentioned at all. There was no exclusive contract signed except for the usual agreement of the freelance site. I am not sure if software development comes under work for hire and is it valid for users outside of the US? The reason for not sharing the source code was this was a very small project and I got paid for a mere few hours. So if I have an option then definitely I would want to keep the source code to myself as that gives a possibility of the client coming back. The application works flawlessly and the code is solid. Also, the task that the client wanted to achieve was very challenging and I would not like other programmers (competitors) to know how I achieved it. So unless I get the confirmation that the source code is purely the property of the client, I would not be willing to share it.

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  • Code Trivia #7

    - by João Angelo
    Lets go for another code trivia, it’s business as usual, you just need to find what’s wrong with the following code: static void Main(string[] args) { using (var file = new FileStream("test", FileMode.Create) { WriteTimeout = 1 }) { file.WriteByte(0); } } TIP: There’s something very wrong with this specific code and there’s also another subtle problem that arises due to how the code is structured.

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  • Code review recommendations and Code Smells

    - by Michael Freidgeim
    Some time ago Twitter told that I am similar to Boris Lipschitz . Indeed he is also .Net programmer from Russia living in Australia. I‘ve read his list of Code Review points and found them quite comprehensive. A few points  were not clear for me, and it forced me for a further reading.In particular the statement “Exception should not be used to return a status or an error code.” wasn’t fully clear for me, because sometimes we store an exception as an object with all error details and I believe it’s a valid approach. However I agree that throwing exceptions should be avoided, if you expect to return error as a part of a normal flow. Related link: http://codeutopia.net/blog/2010/03/11/should-a-failed-function-return-a-value-or-throw-an-exception/ Another point slightly puzzled me“If Thread.Sleep() is used, can it be replaced with something else, ei Timer, AutoResetEvent, etc” . I believe, that there are very rare cases, when anyone using Thread.Sleep in any production code. Usually it is used in mocks and prototypes.I had to look further to clarify “Dependency injection is used instead of Service Location pattern”.Even most of articles has some preferences to Dependency injection, there are also advantages to use Service Location. E.g see http://geekswithblogs.net/KyleBurns/archive/2012/04/27/dependency-injection-vs.-service-locator.aspx. http://www.cookcomputing.com/blog/archives/000587.html  refers to Concluding Thoughts of Martin Fowler The choice between Service Locator and Dependency Injection is less important than the principle of separating service configuration from the use of services within an applicationThe post had a link to excellent article Code Smells of Jeff Atwood, but the statement, that “code should not pass a review if it violates any of the  code smells” sound too strict for my environment. In particular, I disagree with “Dead Code” recommendation “Ruthlessly delete code that isn't being used. That's why we have source control systems!”. If there is a chance that not used code will be required in a future, it is convenient to keep it as commented or #if/#endif blocks with appropriate explanation, why it could be required in the future. TFS is a good source control system, but context search in source code of current solution is much easier than finding something in the previous versions of the code.I also found a link to a good book “Clean Code.A.Handbook.of.Agile.Software”

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  • How can the Kindle be used as a source code reading tool?

    - by Homer6
    I'm a programmer. I want to be a better programmer. I want to read more source code written by other people (especially open source projects). Also, I'd like to be able to have a on-hand searchable reference to all of that source code so that I can pull up reference to structures and snippets. Does anyone know of a way to use the Kindle for this? Has anyone tried? What were your findings? Additionally, does anyone know of a website that indexes all open source source code?

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  • What is New in ASP.NET 4.0 Code Access Security

    - by Xiaohong
    ASP.NET Code Access Security (CAS) is a feature that helps protect server applications on hosting multiple Web sites, ASP.NET lets you assign a configurable trust level that corresponds to a predefined set of permissions. ASP.NET has predefined ASP.NET Trust Levels and Policy Files that you can assign to applications, you also can assign custom trust level and policy files. Most web hosting companies run ASP.NET applications in Medium Trust to prevent that one website affect or harm another site etc. As .NET Framework's Code Access Security model has evolved, ASP.NET 4.0 Code Access Security also has introduced several changes and improvements. The main change in ASP.NET 4.0 CAS In ASP.NET v4.0 partial trust applications, application domain can have a default partial trust permission set as opposed to being full-trust, the permission set name is defined in the <trust /> new attribute permissionSetName that is used to initialize the application domain . By default, the PermissionSetName attribute value is "ASP.Net" which is the name of the permission set you can find in all predefined partial trust configuration files. <trust level="Something" permissionSetName="ASP.Net" /> This is ASP.NET 4.0 new CAS model. For compatibility ASP.NET 4.0 also support legacy CAS model where application domain still has full trust permission set. You can specify new legacyCasModel attribute on the <trust /> element to indicate whether the legacy CAS model is enabled. By default legacyCasModel is false which means that new 4.0 CAS model is the default. <trust level="Something" legacyCasModel="true|false" /> In .Net FX 4.0 Config directory, there are two set of predefined partial trust config files for each new CAS model and legacy CAS model, trust config files with name legacy.XYZ.config are for legacy CAS model: New CAS model: Legacy CAS model: web_hightrust.config legacy.web_hightrust.config web_mediumtrust.config legacy.web_mediumtrust.config web_lowtrust.config legacy.web_lowtrust.config web_minimaltrust.config legacy.web_minimaltrust.config   The figure below shows in ASP.NET 4.0 new CAS model what permission set to grant to code for partial trust application using predefined partial trust levels and policy files:    There also some benefits that comes with the new CAS model: You can lock down a machine by making all managed code no-execute by default (e.g. setting the MyComputer zone to have no managed execution code permissions), it should still be possible to configure ASP.NET web applications to run as either full-trust or partial trust. UNC share doesn’t require full trust with CASPOL at machine-level CAS policy. Side effect that comes with the new CAS model: processRequestInApplicationTrust attribute is deprecated  in new CAS model since application domain always has partial trust permission set in new CAS model.   In ASP.NET 4.0 legacy CAS model or ASP.NET 2.0 CAS model, even though you assign partial trust level to a application but the application domain still has full trust permission set. The figure below shows in ASP.NET 4.0 legacy CAS model (or ASP.NET 2.0 CAS model) what permission set to grant to code for partial trust application using predefined partial trust levels and policy files:     What $AppDirUrl$, $CodeGen$, $Gac$ represents: $AppDirUrl$ The application's virtual root directory. This allows permissions to be applied to code that is located in the application's bin directory. For example, if a virtual directory is mapped to C:\YourWebApp, then $AppDirUrl$ would equate to C:\YourWebApp. $CodeGen$ The directory that contains dynamically generated assemblies (for example, the result of .aspx page compiles). This can be configured on a per application basis and defaults to %windir%\Microsoft.NET\Framework\{version}\Temporary ASP.NET Files. $CodeGen$ allows permissions to be applied to dynamically generated assemblies. $Gac$ Any assembly that is installed in the computer's global assembly cache (GAC). This allows permissions to be granted to strong named assemblies loaded from the GAC by the Web application.   The new customization of CAS Policy in ASP.NET 4.0 new CAS model 1. Define which named permission set in partial trust configuration files By default the permission set that will be assigned at application domain initialization time is the named "ASP.Net" permission set found in all predefined partial trust configuration files. However ASP.NET 4.0 allows you set PermissionSetName attribute to define which named permission set in a partial trust configuration file should be the one used to initialize an application domain. Example: add "ASP.Net_2" named permission set in partial trust configuration file: <PermissionSet class="NamedPermissionSet" version="1" Name="ASP.Net_2"> <IPermission class="FileIOPermission" version="1" Read="$AppDir$" PathDiscovery="$AppDir$" /> <IPermission class="ReflectionPermission" version="1" Flags ="RestrictedMemberAccess" /> <IPermission class="SecurityPermission " version="1" Flags ="Execution, ControlThread, ControlPrincipal, RemotingConfiguration" /></PermissionSet> Then you can use "ASP.Net_2" named permission set for the application domain permission set: <trust level="Something" legacyCasModel="false" permissionSetName="ASP.Net_2" /> 2. Define a custom set of Full Trust Assemblies for an application By using the new fullTrustAssemblies element to configure a set of Full Trust Assemblies for an application, you can modify set of partial trust assemblies to full trust at the machine, site or application level. The configuration definition is shown below: <fullTrustAssemblies> <add assemblyName="MyAssembly" version="1.1.2.3" publicKey="hex_char_representation_of_key_blob" /></fullTrustAssemblies> 3. Define <CodeGroup /> policy in partial trust configuration files ASP.NET 4.0 new CAS model will retain the ability for developers to optionally define <CodeGroup />with membership conditions and assigned permission sets. The specific restriction in ASP.NET 4.0 new CAS model though will be that the results of evaluating custom policies can only result in one of two outcomes: either an assembly is granted full trust, or an assembly is granted the partial trust permission set currently associated with the running application domain. It will not be possible to use custom policies to create additional custom partial trust permission sets. When parsing the partial trust configuration file: Any assemblies that match to code groups associated with "PermissionSet='FullTrust'" will run at full trust. Any assemblies that match to code groups associated with "PermissionSet='Nothing'" will result in a PolicyError being thrown from the CLR. This is acceptable since it provides administrators with a way to do a blanket-deny of managed code followed by selectively defining policy in a <CodeGroup /> that re-adds assemblies that would be allowed to run. Any assemblies that match to code groups associated with other permissions sets will be interpreted to mean the assembly should run at the permission set of the appdomain. This means that even though syntactically a developer could define additional "flavors" of partial trust in an ASP.NET partial trust configuration file, those "flavors" will always be ignored. Example: defines full trust in <CodeGroup /> for my strong named assemblies in partial trust config files: <CodeGroup class="FirstMatchCodeGroup" version="1" PermissionSetName="Nothing"> <IMembershipCondition    class="AllMembershipCondition"    version="1" /> <CodeGroup    class="UnionCodeGroup"    version="1"    PermissionSetName="FullTrust"    Name="My_Strong_Name"    Description="This code group grants code signed full trust. "> <IMembershipCondition      class="StrongNameMembershipCondition" version="1"       PublicKeyBlob="hex_char_representation_of_key_blob" /> </CodeGroup> <CodeGroup   class="UnionCodeGroup" version="1" PermissionSetName="ASP.Net">   <IMembershipCondition class="UrlMembershipCondition" version="1" Url="$AppDirUrl$/*" /> </CodeGroup> <CodeGroup class="UnionCodeGroup" version="1" PermissionSetName="ASP.Net">   <IMembershipCondition class="UrlMembershipCondition" version="1" Url="$CodeGen$/*"   /> </CodeGroup></CodeGroup>   4. Customize CAS policy at runtime in ASP.NET 4.0 new CAS model ASP.NET 4.0 new CAS model allows to customize CAS policy at runtime by using custom HostSecurityPolicyResolver that overrides the ASP.NET code access security policy. Example: use custom host security policy resolver to resolve partial trust web application bin folder MyTrustedAssembly.dll to full trust at runtime: You can create a custom host security policy resolver and compile it to assembly MyCustomResolver.dll with strong name enabled and deploy in GAC: public class MyCustomResolver : HostSecurityPolicyResolver{ public override HostSecurityPolicyResults ResolvePolicy(Evidence evidence) { IEnumerator hostEvidence = evidence.GetHostEnumerator(); while (hostEvidence.MoveNext()) { object hostEvidenceObject = hostEvidence.Current; if (hostEvidenceObject is System.Security.Policy.Url) { string assemblyName = hostEvidenceObject.ToString(); if (assemblyName.Contains(“MyTrustedAssembly.dll”) return HostSecurityPolicyResult.FullTrust; } } //default fall-through return HostSecurityPolicyResult.DefaultPolicy; }} Because ASP.NET accesses the custom HostSecurityPolicyResolver during application domain initialization, and a custom policy resolver requires full trust, you also can add a custom policy resolver in <fullTrustAssemblies /> , or deploy in the GAC. You also need configure a custom HostSecurityPolicyResolver instance by adding the HostSecurityPolicyResolverType attribute in the <trust /> element: <trust level="Something" legacyCasModel="false" hostSecurityPolicyResolverType="MyCustomResolver, MyCustomResolver" permissionSetName="ASP.Net" />   Note: If an assembly policy define in <CodeGroup/> and also in hostSecurityPolicyResolverType, hostSecurityPolicyResolverType will win. If an assembly added in <fullTrustAssemblies/> then the assembly has full trust no matter what policy in <CodeGroup/> or in hostSecurityPolicyResolverType.   Other changes in ASP.NET 4.0 CAS Use the new transparency model introduced in .Net Framework 4.0 Change in dynamically compiled code generated assemblies by ASP.NET: In new CAS model they will be marked as security transparent level2 to use Framework 4.0 security transparent rule that means partial trust code is treated as completely Transparent and it is more strict enforcement. In legacy CAS model they will be marked as security transparent level1 to use Framework 2.0 security transparent rule for compatibility. Most of ASP.NET products runtime assemblies are also changed to be marked as security transparent level2 to switch to SecurityTransparent code by default unless SecurityCritical or SecuritySafeCritical attribute specified. You also can look at Security Changes in the .NET Framework 4 for more information about these security attributes. Support conditional APTCA If an assembly is marked with the Conditional APTCA attribute to allow partially trusted callers, and if you want to make the assembly both visible and accessible to partial-trust code in your web application, you must add a reference to the assembly in the partialTrustVisibleAssemblies section: <partialTrustVisibleAssemblies> <add assemblyName="MyAssembly" publicKey="hex_char_representation_of_key_blob" />/partialTrustVisibleAssemblies>   Most of ASP.NET products runtime assemblies are also changed to be marked as conditional APTCA to prevent use of ASP.NET APIs in partial trust environments such as Winforms or WPF UI controls hosted in Internet Explorer.   Differences between ASP.NET new CAS model and legacy CAS model: Here list some differences between ASP.NET new CAS model and legacy CAS model ASP.NET 4.0 legacy CAS model  : Asp.net partial trust appdomains have full trust permission Multiple different permission sets in a single appdomain are allowed in ASP.NET partial trust configuration files Code groups Machine CAS policy is honored processRequestInApplicationTrust attribute is still honored    New configuration setting for legacy model: <trust level="Something" legacyCASModel="true" ></trust><partialTrustVisibleAssemblies> <add assemblyName="MyAssembly" publicKey="hex_char_representation_of_key_blob" /></partialTrustVisibleAssemblies>   ASP.NET 4.0 new CAS model: ASP.NET will now run in homogeneous application domains. Only full trust or the app-domain's partial trust grant set, are allowable permission sets. It is no longer possible to define arbitrary permission sets that get assigned to different assemblies. If an application currently depends on fine-tuning the partial trust permission set using the ASP.NET partial trust configuration file, this will no longer be possible. processRequestInApplicationTrust attribute is deprecated Dynamically compiled assemblies output by ASP.NET build providers will be updated to explicitly mark assemblies as transparent. ASP.NET partial trust grant sets will be independent from any enterprise, machine, or user CAS policy levels. A simplified model for locking down web servers that only allows trusted managed web applications to run. Machine policy used to always grant full-trust to managed code (based on membership conditions) can instead be configured using the new ASP.NET 4.0 full-trust assembly configuration section. The full-trust assembly configuration section requires explicitly listing each assembly as opposed to using membership conditions. Alternatively, the membership condition(s) used in machine policy can instead be re-defined in a <CodeGroup /> within ASP.NET's partial trust configuration file to grant full-trust.   New configuration setting for new model: <trust level="Something" legacyCASModel="false" permissionSetName="ASP.Net" hostSecurityPolicyResolverType=".NET type string" ></trust><fullTrustAssemblies> <add assemblyName=”MyAssembly” version=”1.0.0.0” publicKey="hex_char_representation_of_key_blob" /></fullTrustAssemblies><partialTrustVisibleAssemblies> <add assemblyName="MyAssembly" publicKey="hex_char_representation_of_key_blob" /></partialTrustVisibleAssemblies>     Hope this post is helpful to better understand the ASP.Net 4.0 CAS. Xiaohong Tang ASP.NET QA Team

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  • Tips on a tool to measure code quality?

    - by Cristi Diaconescu
    I'm looking for a tool that can provide code quality metrics. For instance it could report very long functions (spaghetti code) very complex classes (which could contain do-it-all code) ... While we're on the (subjective:-) subject of code quality, what other code metrics would you suggest? I'm targetting C#/.NET code, but I'm sure this could extend to most programming languages.

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  • Visual Studio 2013 Static Code Analysis in depth: What? When and How?

    - by Hosam Kamel
    In this post I'll illustrate in details the following points What is static code analysis? When to use? Supported platforms Supported Visual Studio versions How to use Run Code Analysis Manually Run Code Analysis Automatically Run Code Analysis while check-in source code to TFS version control (TFSVC) Run Code Analysis as part of Team Build Understand the Code Analysis results & learn how to fix them Create your custom rule set Q & A References What is static Rule analysis? Static Code Analysis feature of Visual Studio performs static code analysis on code to help developers identify potential design, globalization, interoperability, performance, security, and a lot of other categories of potential problems according to Microsoft's rules that mainly targets best practices in writing code, and there is a large set of those rules included with Visual Studio grouped into different categorized targeting specific coding issues like security, design, Interoperability, globalizations and others. Static here means analyzing the source code without executing it and this type of analysis can be performed through automated tools (like Visual Studio 2013 Code Analysis Tool) or manually through Code Review which already supported in Visual Studio 2012 and 2013 (check Using Code Review to Improve Quality video on Channel9) There is also Dynamic analysis which performed on executing programs using software testing techniques such as Code Coverage for example. When to use? Running Code analysis tool at regular intervals during your development process can enhance the quality of your software, examines your code for a set of common defects and violations is always a good programming practice. Adding that Code analysis can also find defects in your code that are difficult to discover through testing allowing you to achieve first level quality gate for you application during development phase before you release it to the testing team. Supported platforms .NET Framework, native (C and C++) Database applications. Support Visual Studio versions All version of Visual Studio starting Visual Studio 2013 (except Visual Studio Test Professional) check Feature comparisons Create and modify a custom rule set required Visual Studio Premium or Ultimate. How to use? Code Analysis can be run manually at any time from within the Visual Studio IDE, or even setup to automatically run as part of a Team Build or check-in policy for Team Foundation Server. Run Code Analysis Manually To run code analysis manually on a project, on the Analyze menu, click Run Code Analysis on your project or simply right click on the project name on the Solution Explorer choose Run Code Analysis from the context menu Run Code Analysis Automatically To run code analysis each time that you build a project, you select Enable Code Analysis on Build on the project's Property Page Run Code Analysis while check-in source code to TFS version control (TFSVC) Team Foundation Version Control (TFVC) provides a way for organizations to enforce practices that lead to better code and more efficient group development through Check-in policies which are rules that are set at the team project level and enforced on developer computers before code is allowed to be checked in. (This is available only if you're using Team Foundation Server) Require permissions on Team Foundation Server: you must have the Edit project-level information permission set to Allow typically your account must be part of Project Administrators, Project Collection Administrators, for more information about Team Foundation permissions check http://msdn.microsoft.com/en-us/library/ms252587(v=vs.120).aspx In Team Explorer, right-click the team project name, point to Team Project Settings, and then click Source Control. In the Source Control dialog box, select the Check-in Policy tab. Click Add to create a new check-in policy. Double-click the existing Code Analysis item in the Policy Type list to change the policy. Check or Uncheck the policy option based on the configurations you need to perform as illustrated below: Enforce check-in to only contain files that are part of current solution: code analysis can run only on files specified in solution and project configuration files. This policy guarantees that all code that is part of a solution is analyzed. Enforce C/C++ Code Analysis (/analyze): Requires that all C or C++ projects be built with the /analyze compiler option to run code analysis before they can be checked in. Enforce Code Analysis for Managed Code: Requires that all managed projects run code analysis and build before they can be checked in. Check Code analysis rule set reference on MSDN What is Rule Set? Rule Set is a group of code analysis rules like the example below where Microsoft.Design is the rule set name where "Do not declare static members on generic types" is the code analysis rule Once you configured the Analysis rule the policy will be enabled for all the team member in this project whenever a team member check-in any source code to the TFSVC the policy section will highlight the Code Analysis policy as below TFS is a very extensible platform so you can simply implement your own custom Code Analysis Check-in policy, check this link for more details http://msdn.microsoft.com/en-us/library/dd492668.aspx but you have to be aware also about compatibility between different TFS versions check http://msdn.microsoft.com/en-us/library/bb907157.aspx Run Code Analysis as part of Team Build With Team Foundation Build (TFBuild), you can create and manage build processes that automatically compile and test your applications, and perform other important functions. Code Analysis can be enabled in the Build Definition file by selecting the correct value for the build process parameter "Perform Code Analysis" Once configure, Kick-off your build definition to queue a new build, Code Analysis will run as part of build workflow and you will be able to see code analysis warning as part of build report Understand the Code Analysis results & learn how to fix them Now after you went through Code Analysis configurations and the different ways of running it, we will go through the Code Analysis result how to understand them and how to resolve them. Code Analysis window in Visual Studio will show all the analysis results based on the rule sets you configured in the project file properties, let's dig deep into what each result item contains: 1 Check ID The unique identifier for the rule. CheckId and Category are used for in-source suppression of a warning.       2 Title The title of warning message       3 Description A description of the problem or suggested fix 4 File Name File name and the line of code number which violate the code analysis rule set 5 Category The code analysis category for this error 6 Warning /Error Depend on how you configure it in the rule set the default is Warning level 7 Action Copy: copy the warning information to the clipboard Create Work Item: If you're connected to Team Foundation Server you can create a work item most probably you may create a Task or Bug and assign it for a developer to fix certain code analysis warning Suppress Message: There are times when you might decide not to fix a code analysis warning. You might decide that resolving the warning requires too much recoding in relation to the probability that the issue will arise in any real-world implementation of your code. Or you might believe that the analysis that is used in the warning is inappropriate for the particular context. You can suppress individual warnings so that they no longer appear in the Code Analysis window. Two options available: In Source inserts a SuppressMessage attribute in the source file above the method that generated the warning. This makes the suppression more discoverable. In Suppression File adds a SuppressMessage attribute to the GlobalSuppressions.cs file of the project. This can make the management of suppressions easier. Note that the SuppressMessage attribute added to GlobalSuppression.cs also targets the method that generated the warning. It does not suppress the warning globally.       Visual Studio makes it very easy to fix Code analysis warning, all you have to do is clicking on the Check Id hyperlink if you are not aware how to fix the warring and you'll be directed to MSDN online or local copy based on the configuration you did while installing Visual Studio and you will find all the information about the warring including how to fix it. Create a Custom Code Analysis Rule Set The Microsoft standard rule sets provide groups of rules that are organized by function and depth. For example, the Microsoft Basic Design Guidelines Rules and the Microsoft Extended Design Guidelines Rules contain rules that focus on usability and maintainability issues, with added emphasis on naming rules in the Extended rule set, you can create and modify a custom rule set to meet specific project needs associated with code analysis. To create a custom rule set, you open one or more standard rule sets in the rule set editor. Create and modify a custom rule set required Visual Studio Premium or Ultimate. You can check How to: Create a Custom Rule Set on MSDN for more details http://msdn.microsoft.com/en-us/library/dd264974.aspx Q & A Visual Studio static code analysis vs. FxCop vs. StyleCpp http://www.excella.com/blog/stylecop-vs-fxcop-difference-between-code-analysis-tools/ Code Analysis for SharePoint Apps and SPDisposeCheck? This post lists some of the rule set you can run specifically for SharePoint applications and how to integrate SPDisposeCheck as well. Code Analysis for SQL Server Database Projects? This post illustrate how to run static code analysis on T-SQL through SSDT ReSharper 8 vs. Visual Studio 2013? This document lists some of the features that are provided by ReSharper 8 but are missing or not as fully implemented in Visual Studio 2013. References A Few Billion Lines of Code Later: Using Static Analysis to Find Bugs in the Real World http://cacm.acm.org/magazines/2010/2/69354-a-few-billion-lines-of-code-later/fulltext What is New in Code Analysis for Visual Studio 2013 http://blogs.msdn.com/b/visualstudioalm/archive/2013/07/03/what-is-new-in-code-analysis-for-visual-studio-2013.aspx Analyze the code quality of Windows Store apps using Visual Studio static code analysis http://msdn.microsoft.com/en-us/library/windows/apps/hh441471.aspx [Hands-on-lab] Using Code Analysis with Visual Studio 2012 to Improve Code Quality http://download.microsoft.com/download/A/9/2/A9253B14-5F23-4BC8-9C7E-F5199DB5F831/Using%20Code%20Analysis%20with%20Visual%20Studio%202012%20to%20Improve%20Code%20Quality.docx Originally posted at "Hosam Kamel| Developer & Platform Evangelist" http://blogs.msdn.com/hkamel

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  • How can I promote clean coding at my workplace?

    - by Michael
    I work with a lot of legacy Java and RPG code on an internal company application. As you might expect, a lot of the code is written in many different styles, and often is difficult to read because of poorly named variables, inconsistent formatting, and contradictory comments (if they're there at all). Also, a good amount of code is not robust. Many times code is pushed to production quickly by the more experienced programmers, while code by newer programmers is held back by "code reviews" that IMO are unsatisfactory. (They usually take the form of, "It works, must be ok," than a serious critique of the code.) We have a fair number of production issues, which I feel could be lessened by giving more thought to the original design and testing. I have been working for this company for about 4 months, and have been complimented on my coding style a couple of times. My manager is also a fan of cleaner coding than is the norm. Is it my place to try to push for better style and better defensive coding, or should I simply code in the best way I can, and hope that my example will help others see how cleaner, more robust code (as well as aggressive refactoring) will result in less debugging and change time?

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  • How should Code Review be Carried Out?

    - by Graviton
    My previous question has to do with how to advance code review among the developers. Here I am interested in how the code review session should be carried out, so that both the reviewer and reviewed are feeling comfortable about it. I have done some code review before, but the experience sucks big time. My previous manager would come to us-- on an ad hoc basis-- and tell us to explain our code to him. Since he wasn't very familiar with the code base, I spent a huge amount of times explaining just the most basic structure of my code to him. This took a long time and by the time we were done, we were both exhausted. Then he would raise issues with my code. Most issues he raised were cosmetic in nature ( e.g, don't use region for this code block, change the variable name from xxx to yyy even though the later makes even less sense, and so on). We did this a few rounds, and the review session didn't derive much benefits for us, and we stopped. What do you have to do, in order to make code review a natural, enjoyable, thought stimulating, bug-fixing and mutual-learning experience?

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  • Advancing Code Review and Unit Testing Practice

    - by Graviton
    As a team lead managing a group of developers with no experience ( and see no need) in code review and unit testing, how can you advance code review and unit testing practice? How are you going to create a way so that code review and unit testing to naturally fit into the developer's flow? One of the resistance of these two areas is that "we are always tight on dateline, so no time for code review and unit testing". Another resistance for code review is that we currently don't know how to do it. Should we review the code upon every check-in, or review the code at a specified date?

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  • What defines code readability?

    - by zxcdw
    It is often said that readability is perhaps the most important quality-defining measure of a given piece of code for reasons concerning maintainability, ease of understanding and use. What defines the word readable in context of program source code? What kind of definitive aspects are there to code readability? I would be grateful with code examples of readable code, along with reasoning why it is readable.

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  • Diagram to show code responsibility

    - by Mike Samuel
    Does anyone know how to visually diagram the ways in which the flow of control in code passes between code produced by different groups and how that affects the amount of code that needs to be carefully written/reviewed/tested for system properties to hold? What I am trying to help people visualize are arguments of the form: For property P to hold, nd developers have to write application code, Ca, without certain kinds of errors, and nm maintainers have to make sure that the code continues to not have these kinds of errors over the project lifetime. We could reduce the error rate by educating nd developers and nm maintainers. For us to be confident that the property holds, ns specialists still need to test or check |Ca| lines of code and continue to test/check the changes by nm maintainers. Alternatively, we could be confident that P holds if all code paths that could violate P went through tool code, Ct, written by our specialists. In our case, test suites alone cannot give confidence that P holdsnd » nsnm ns|Ca| » |Ct| so writing and maintaining Ct is economical, frees up our developers to worry about other things, and reduces the ongoing education commitment by our specialists. or those conditions do not hold, so focusing on education and testing is preferable. Example 1 As a concrete example, suppose we want to ensure that our web-service only produces valid JSON output. Our web-service provides several query and mutation operators that can be composed in interesting ways. We could try to educate everyone who maintains those operations about the JSON syntax, the importance of conformance, and libraries available so that when they write to an output buffer, every possible sequence of appends results in syntactically valid JSON. Alternatively, we don't expose an output stream handle to application code, and instead expose a JSON sink so that every code path that writes a response is channeled through a JSON sink that is written and maintained by a specialist who knows JSON syntax and can use well-written libraries to produce only valid output. Example 2 We need to make sure that a service that receives a URL from an untrusted source and tries to fetch its content does not end up revealing sensitive files from the file-system, like file:///etc/passwd. If there is a single standard way that any developer familiar with the application language's libraries would use to fetch URLs, which has file-system access turned off by default, then simply educating developers about the standard mechanism, and testing that file probing fails for some inputs, will probably be sufficient.

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  • Announcing Entity Framework Code-First (CTP5 release)

    - by ScottGu
    This week the data team released the CTP5 build of the new Entity Framework Code-First library.  EF Code-First enables a pretty sweet code-centric development workflow for working with data.  It enables you to: Develop without ever having to open a designer or define an XML mapping file Define model objects by simply writing “plain old classes” with no base classes required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping I’m a big fan of the EF Code-First approach, and wrote several blog posts about it this summer: Code-First Development with Entity Framework 4 (July 16th) EF Code-First: Custom Database Schema Mapping (July 23rd) Using EF Code-First with an Existing Database (August 3rd) Today’s new CTP5 release delivers several nice improvements over the CTP4 build, and will be the last preview build of Code First before the final release of it.  We will ship the final EF Code First release in the first quarter of next year (Q1 of 2011).  It works with all .NET application types (including both ASP.NET Web Forms and ASP.NET MVC projects). Installing EF Code First You can install and use EF Code First CTP5 using one of two ways: Approach 1) By downloading and running a setup program.  Once installed you can reference the EntityFramework.dll assembly it provides within your projects.      or: Approach 2) By using the NuGet Package Manager within Visual Studio to download and install EF Code First within a project.  To do this, simply bring up the NuGet Package Manager Console within Visual Studio (View->Other Windows->Package Manager Console) and type “Install-Package EFCodeFirst”: Typing “Install-Package EFCodeFirst” within the Package Manager Console will cause NuGet to download the EF Code First package, and add it to your current project: Doing this will automatically add a reference to the EntityFramework.dll assembly to your project:   NuGet enables you to have EF Code First setup and ready to use within seconds.  When the final release of EF Code First ships you’ll also be able to just type “Update-Package EFCodeFirst” to update your existing projects to use the final release. EF Code First Assembly and Namespace The CTP5 release of EF Code First has an updated assembly name, and new .NET namespace: Assembly Name: EntityFramework.dll Namespace: System.Data.Entity These names match what we plan to use for the final release of the library. Nice New CTP5 Improvements The new CTP5 release of EF Code First contains a bunch of nice improvements and refinements. Some of the highlights include: Better support for Existing Databases Built-in Model-Level Validation and DataAnnotation Support Fluent API Improvements Pluggable Conventions Support New Change Tracking API Improved Concurrency Conflict Resolution Raw SQL Query/Command Support The rest of this blog post contains some more details about a few of the above changes. Better Support for Existing Databases EF Code First makes it really easy to create model layers that work against existing databases.  CTP5 includes some refinements that further streamline the developer workflow for this scenario. Below are the steps to use EF Code First to create a model layer for the Northwind sample database: Step 1: Create Model Classes and a DbContext class Below is all of the code necessary to implement a simple model layer using EF Code First that goes against the Northwind database: EF Code First enables you to use “POCO” – Plain Old CLR Objects – to represent entities within a database.  This means that you do not need to derive model classes from a base class, nor implement any interfaces or data persistence attributes on them.  This enables the model classes to be kept clean, easily testable, and “persistence ignorant”.  The Product and Category classes above are examples of POCO model classes. EF Code First enables you to easily connect your POCO model classes to a database by creating a “DbContext” class that exposes public properties that map to the tables within a database.  The Northwind class above illustrates how this can be done.  It is mapping our Product and Category classes to the “Products” and “Categories” tables within the database.  The properties within the Product and Category classes in turn map to the columns within the Products and Categories tables – and each instance of a Product/Category object maps to a row within the tables. The above code is all of the code required to create our model and data access layer!  Previous CTPs of EF Code First required an additional step to work against existing databases (a call to Database.Initializer<Northwind>(null) to tell EF Code First to not create the database) – this step is no longer required with the CTP5 release.  Step 2: Configure the Database Connection String We’ve written all of the code we need to write to define our model layer.  Our last step before we use it will be to setup a connection-string that connects it with our database.  To do this we’ll add a “Northwind” connection-string to our web.config file (or App.Config for client apps) like so:   <connectionStrings>          <add name="Northwind"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\northwind.mdf;User Instance=true"          providerName="System.Data.SqlClient" />   </connectionStrings> EF “code first” uses a convention where DbContext classes by default look for a connection-string that has the same name as the context class.  Because our DbContext class is called “Northwind” it by default looks for a “Northwind” connection-string to use.  Above our Northwind connection-string is configured to use a local SQL Express database (stored within the \App_Data directory of our project).  You can alternatively point it at a remote SQL Server. Step 3: Using our Northwind Model Layer We can now easily query and update our database using the strongly-typed model layer we just built with EF Code First. The code example below demonstrates how to use LINQ to query for products within a specific product category.  This query returns back a sequence of strongly-typed Product objects that match the search criteria: The code example below demonstrates how we can retrieve a specific Product object, update two of its properties, and then save the changes back to the database: EF Code First handles all of the change-tracking and data persistence work for us, and allows us to focus on our application and business logic as opposed to having to worry about data access plumbing. Built-in Model Validation EF Code First allows you to use any validation approach you want when implementing business rules with your model layer.  This enables a great deal of flexibility and power. Starting with this week’s CTP5 release, EF Code First also now includes built-in support for both the DataAnnotation and IValidatorObject validation support built-into .NET 4.  This enables you to easily implement validation rules on your models, and have these rules automatically be enforced by EF Code First whenever you save your model layer.  It provides a very convenient “out of the box” way to enable validation within your applications. Applying DataAnnotations to our Northwind Model The code example below demonstrates how we could add some declarative validation rules to two of the properties of our “Product” model: We are using the [Required] and [Range] attributes above.  These validation attributes live within the System.ComponentModel.DataAnnotations namespace that is built-into .NET 4, and can be used independently of EF.  The error messages specified on them can either be explicitly defined (like above) – or retrieved from resource files (which makes localizing applications easy). Validation Enforcement on SaveChanges() EF Code-First (starting with CTP5) now automatically applies and enforces DataAnnotation rules when a model object is updated or saved.  You do not need to write any code to enforce this – this support is now enabled by default.  This new support means that the below code – which violates our above rules – will automatically throw an exception when we call the “SaveChanges()” method on our Northwind DbContext: The DbEntityValidationException that is raised when the SaveChanges() method is invoked contains a “EntityValidationErrors” property that you can use to retrieve the list of all validation errors that occurred when the model was trying to save.  This enables you to easily guide the user on how to fix them.  Note that EF Code-First will abort the entire transaction of changes if a validation rule is violated – ensuring that our database is always kept in a valid, consistent state. EF Code First’s validation enforcement works both for the built-in .NET DataAnnotation attributes (like Required, Range, RegularExpression, StringLength, etc), as well as for any custom validation rule you create by sub-classing the System.ComponentModel.DataAnnotations.ValidationAttribute base class. UI Validation Support A lot of our UI frameworks in .NET also provide support for DataAnnotation-based validation rules. For example, ASP.NET MVC, ASP.NET Dynamic Data, and Silverlight (via WCF RIA Services) all provide support for displaying client-side validation UI that honor the DataAnnotation rules applied to model objects. The screen-shot below demonstrates how using the default “Add-View” scaffold template within an ASP.NET MVC 3 application will cause appropriate validation error messages to be displayed if appropriate values are not provided: ASP.NET MVC 3 supports both client-side and server-side enforcement of these validation rules.  The error messages displayed are automatically picked up from the declarative validation attributes – eliminating the need for you to write any custom code to display them. Keeping things DRY The “DRY Principle” stands for “Do Not Repeat Yourself”, and is a best practice that recommends that you avoid duplicating logic/configuration/code in multiple places across your application, and instead specify it only once and have it apply everywhere. EF Code First CTP5 now enables you to apply declarative DataAnnotation validations on your model classes (and specify them only once) and then have the validation logic be enforced (and corresponding error messages displayed) across all applications scenarios – including within controllers, views, client-side scripts, and for any custom code that updates and manipulates model classes. This makes it much easier to build good applications with clean code, and to build applications that can rapidly iterate and evolve. Other EF Code First Improvements New to CTP5 EF Code First CTP5 includes a bunch of other improvements as well.  Below are a few short descriptions of some of them: Fluent API Improvements EF Code First allows you to override an “OnModelCreating()” method on the DbContext class to further refine/override the schema mapping rules used to map model classes to underlying database schema.  CTP5 includes some refinements to the ModelBuilder class that is passed to this method which can make defining mapping rules cleaner and more concise.  The ADO.NET Team blogged some samples of how to do this here. Pluggable Conventions Support EF Code First CTP5 provides new support that allows you to override the “default conventions” that EF Code First honors, and optionally replace them with your own set of conventions. New Change Tracking API EF Code First CTP5 exposes a new set of change tracking information that enables you to access Original, Current & Stored values, and State (e.g. Added, Unchanged, Modified, Deleted).  This support is useful in a variety of scenarios. Improved Concurrency Conflict Resolution EF Code First CTP5 provides better exception messages that allow access to the affected object instance and the ability to resolve conflicts using current, original and database values.  Raw SQL Query/Command Support EF Code First CTP5 now allows raw SQL queries and commands (including SPROCs) to be executed via the SqlQuery and SqlCommand methods exposed off of the DbContext.Database property.  The results of these method calls can be materialized into object instances that can be optionally change-tracked by the DbContext.  This is useful for a variety of advanced scenarios. Full Data Annotations Support EF Code First CTP5 now supports all standard DataAnnotations within .NET, and can use them both to perform validation as well as to automatically create the appropriate database schema when EF Code First is used in a database creation scenario.  Summary EF Code First provides an elegant and powerful way to work with data.  I really like it because it is extremely clean and supports best practices, while also enabling solutions to be implemented very, very rapidly.  The code-only approach of the library means that model layers end up being flexible and easy to customize. This week’s CTP5 release further refines EF Code First and helps ensure that it will be really sweet when it ships early next year.  I recommend using NuGet to install and give it a try today.  I think you’ll be pleasantly surprised by how awesome it is. Hope this helps, Scott

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  • Entity Association Mapping with Code First Part 1 : Mapping Complex Types

    - by mortezam
    Last week the CTP5 build of the new Entity Framework Code First has been released by data team at Microsoft. Entity Framework Code-First provides a pretty powerful code-centric way to work with the databases. When it comes to associations, it brings ultimate flexibility. I’m a big fan of the EF Code First approach and am planning to explain association mapping with code first in a series of blog posts and this one is dedicated to Complex Types. If you are new to Code First approach, you can find a great walkthrough here. In order to build a solid foundation for our discussion, we will start by learning about some of the core concepts around the relationship mapping.   What is Mapping?Mapping is the act of determining how objects and their relationships are persisted in permanent data storage, in our case, relational databases. What is Relationship mapping?A mapping that describes how to persist a relationship (association, aggregation, or composition) between two or more objects. Types of RelationshipsThere are two categories of object relationships that we need to be concerned with when mapping associations. The first category is based on multiplicity and it includes three types: One-to-one relationships: This is a relationship where the maximums of each of its multiplicities is one. One-to-many relationships: Also known as a many-to-one relationship, this occurs when the maximum of one multiplicity is one and the other is greater than one. Many-to-many relationships: This is a relationship where the maximum of both multiplicities is greater than one. The second category is based on directionality and it contains two types: Uni-directional relationships: when an object knows about the object(s) it is related to but the other object(s) do not know of the original object. To put this in EF terminology, when a navigation property exists only on one of the association ends and not on the both. Bi-directional relationships: When the objects on both end of the relationship know of each other (i.e. a navigation property defined on both ends). How Object Relationships Are Implemented in POCO domain models?When the multiplicity is one (e.g. 0..1 or 1) the relationship is implemented by defining a navigation property that reference the other object (e.g. an Address property on User class). When the multiplicity is many (e.g. 0..*, 1..*) the relationship is implemented via an ICollection of the type of other object. How Relational Database Relationships Are Implemented? Relationships in relational databases are maintained through the use of Foreign Keys. A foreign key is a data attribute(s) that appears in one table and must be the primary key or other candidate key in another table. With a one-to-one relationship the foreign key needs to be implemented by one of the tables. To implement a one-to-many relationship we implement a foreign key from the “one table” to the “many table”. We could also choose to implement a one-to-many relationship via an associative table (aka Join table), effectively making it a many-to-many relationship. Introducing the ModelNow, let's review the model that we are going to use in order to implement Complex Type with Code First. It's a simple object model which consist of two classes: User and Address. Each user could have one billing address. The Address information of a User is modeled as a separate class as you can see in the UML model below: In object-modeling terms, this association is a kind of aggregation—a part-of relationship. Aggregation is a strong form of association; it has some additional semantics with regard to the lifecycle of objects. In this case, we have an even stronger form, composition, where the lifecycle of the part is fully dependent upon the lifecycle of the whole. Fine-grained domain models The motivation behind this design was to achieve Fine-grained domain models. In crude terms, fine-grained means “more classes than tables”. For example, a user may have both a billing address and a home address. In the database, you may have a single User table with the columns BillingStreet, BillingCity, and BillingPostalCode along with HomeStreet, HomeCity, and HomePostalCode. There are good reasons to use this somewhat denormalized relational model (performance, for one). In our object model, we can use the same approach, representing the two addresses as six string-valued properties of the User class. But it’s much better to model this using an Address class, where User has the BillingAddress and HomeAddress properties. This object model achieves improved cohesion and greater code reuse and is more understandable. Complex Types: Splitting a Table Across Multiple Types Back to our model, there is no difference between this composition and other weaker styles of association when it comes to the actual C# implementation. But in the context of ORM, there is a big difference: A composed class is often a candidate Complex Type. But C# has no concept of composition—a class or property can’t be marked as a composition. The only difference is the object identifier: a complex type has no individual identity (i.e. no AddressId defined on Address class) which make sense because when it comes to the database everything is going to be saved into one single table. How to implement a Complex Types with Code First Code First has a concept of Complex Type Discovery that works based on a set of Conventions. The convention is that if Code First discovers a class where a primary key cannot be inferred, and no primary key is registered through Data Annotations or the fluent API, then the type will be automatically registered as a complex type. Complex type detection also requires that the type does not have properties that reference entity types (i.e. all the properties must be scalar types) and is not referenced from a collection property on another type. Here is the implementation: public class User{    public int UserId { get; set; }    public string FirstName { get; set; }    public string LastName { get; set; }    public string Username { get; set; }    public Address Address { get; set; }} public class Address {     public string Street { get; set; }     public string City { get; set; }            public string PostalCode { get; set; }        }public class EntityMappingContext : DbContext {     public DbSet<User> Users { get; set; }        } With code first, this is all of the code we need to write to create a complex type, we do not need to configure any additional database schema mapping information through Data Annotations or the fluent API. Database SchemaThe mapping result for this object model is as follows: Limitations of this mappingThere are two important limitations to classes mapped as Complex Types: Shared references is not possible: The Address Complex Type doesn’t have its own database identity (primary key) and so can’t be referred to by any object other than the containing instance of User (e.g. a Shipping class that also needs to reference the same User Address). No elegant way to represent a null reference There is no elegant way to represent a null reference to an Address. When reading from database, EF Code First always initialize Address object even if values in all mapped columns of the complex type are null. This means that if you store a complex type object with all null property values, EF Code First returns a initialized complex type when the owning entity object is retrieved from the database. SummaryIn this post we learned about fine-grained domain models which complex type is just one example of it. Fine-grained is fully supported by EF Code First and is known as the most important requirement for a rich domain model. Complex type is usually the simplest way to represent one-to-one relationships and because the lifecycle is almost always dependent in such a case, it’s either an aggregation or a composition in UML. In the next posts we will revisit the same domain model and will learn about other ways to map a one-to-one association that does not have the limitations of the complex types. References ADO.NET team blog Mapping Objects to Relational Databases Java Persistence with Hibernate

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