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  • how can I code a recursive query in an Entity Framework model?

    - by Greg
    Hi, I have a model which includes NODES, and RELATIONSHIPS (that tie the nodes together, via a parent_node, child_node arrangement). Q1 - Is there any way in EF / Linq-to-entities to perform a query on nodes (e.g. context.Nodes..) to find say "all parents" or "or children" in the graph? Q2 - If there's not in Linq-to-entities, is there any other way to do this other than writing a method that manually goes through and doing it? Q3 - If manual is the only way to do it, should I be concerned about the number of database hits that will be going out to the database as the method keeps recursing through the data? Or more specifically, is there any EF caching type feature that might assist here in ensuring the method is performance from a "number of database hits" point of view? thanks thanks

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  • How do I map a composite primary key in Entity Framework 4 code first?

    - by jamesfm
    I'm getting to grips with EF4 code first, and liking it so far. But I'm having trouble mapping an entity to a table with a composite primary key. The configuration I've tried looks like this: public SubscriptionUserConfiguration() { Property(u => u.SubscriptionID).IsIdentity(); Property(u => u.UserName).IsIdentity(); } Which throws this exception: Unable to infer a key for entity type 'SubscriptionUser'. What am I missing?

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  • Algorithm design, "randomising" timetable schedule in Python although open to other languages.

    - by S1syphus
    Before I start I should add I am a musician and not a native programmer, this was undertook to make my life easier. Here is the situation, at work I'm given a new csv file each which contains a list of sound files, their length, and the minimum total amount of time they must be played. I create a playlist of exactly 60 minutes, from this excel file. Each sample played the by the minimum number of instances, but spread out from each other; so there will never be a period where for where one sound is played twice in a row or in close proximity to itself. Secondly, if the minimum instances of each song has been used, and there is still time with in the 60 min, it needs to fill the remaining time using sounds till 60 minutes is reached, while adhering to above. The smallest duration possible is 15 seconds, and then multiples of 15 seconds. Here is what I came up with in python and the problems I'm having with it, and as one user said its buggy due to the random library used in it. So I'm guessing a total rethink is on the table, here is where I need your help. Whats is the best way to solve the issue, I have had a brief look at things like knapsack and bin packing algorithms, while both are relevant neither are appropriate and maybe a bit beyond me.

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  • Tracking changes in Entity Framework 4.0 using POCO Dynamic Proxies across multiple data contexts.

    - by Rob Packwood
    I started messing with EF 4.0 because I am curious about the POCO possibilities... I wanted to simulate disconnected web environment and wrote the following code to simulate this: Save a test object in the database. Retrieve the test object Dispose of the DataContext associated with the test object I used to retrieve it Update the test object Create a new data context and persist the changes on the test object that are automatically tracked within the DynamicProxy generated against my POCO object. The problem is that when I call dataContext.SaveChanges in the Test method above, the updates are not applied. The testStore entity shows a status of "Modified" when I check its EntityStateTracker, but it is no longer modified when I view it within the new dataContext's Stores property. I would have thought that calling the Attach method on the new dataContext would also bring the object's "Modified" state over, but that appears to not be the case. Is there something I am missing? I am definitely working with self-tracking POCOs using DynamicProxies. private static void SaveTestStore(string storeName = "TestStore") { using (var context = new DataContext()) { Store newStore = context.Stores.CreateObject(); newStore.Name = storeName; context.Stores.AddObject(newStore); context.SaveChanges(); } } private static Store GetStore(string storeName = "TestStore") { using (var context = new DataContext()) { return (from store in context.Stores where store.Name == storeName select store).SingleOrDefault(); } } [Test] public void Test_Store_Update_Using_Different_DataContext() { SaveTestStore(); Store testStore = GetStore(); testStore.Name = "Updated"; using (var dataContext = new DataContext()) { dataContext.Stores.Attach(testStore); dataContext.SaveChanges(SaveOptions.DetectChangesBeforeSave); } Store updatedStore = GetStore("Updated"); Assert.IsNotNull(updatedStore); }

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  • Entity Framework - Using Transactions or SaveChanges(false) and AcceptAllChanges()?

    - by mark smith
    Hi there, I have been investigating transactions and it appears that they take call of them selves in EF as long as i pass false to savechanges.. SaveChanges(false) and if all goes well then AcceptAllChanges() Question is what is something goes bad, don't have to rollback? or as soon as the my method goes out of scope its ended? What happens to any indentiy columns that were assigned half way through the transaction.. i presume if somebody else added a record after mine before mine went bad then this means there will be a missing Identity value. Is there any reason to use standard "transactionScope" in code? ideas? - thanks

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  • Where are the Entity Framework t4 templates for Data Annotations?

    - by JK
    I have been googling this non stop for 2 days now and can't find a single complete, ready to use, fully implemented t4 template that generates DataAnnotations. Do they even exist? I generate POCOs with the standard t4 templates. The actual database table has metadata that describes some of the validation rules, eg not null, nvarchar(25), etc. So all I want is a t4 template that can take my table and generate a POCO with DataAnnotations, eg public class Person { [Required] [StringLength(255)] public FirstName {get;set} } It is a basic and fundamental requirement, surely I can not be the first person in the entire world to have this requirement? I don't want to re-invent the wheel here. Yet I haven't found it after search high and low for days. This must be possible (and hopefully must be available somewhere to just download) - it would be criminally wrong to have to manually type in these annotations when the metadata for them already exists in the database.

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  • GDI RoundRect on Compact Framework: make rounded rectangle's outside transparent.

    - by VansFannel
    Hello! I'm using the RoundRect GDI function to draw a rounded rectangle following this example: .NET CF Custom Control: RoundedGroupBox Because all controls are square, it also draw the corners outside of the rounded rectangle. How can I make this space left outside the rectangle transparent? The OnPaint method is: protected override void OnPaint(PaintEventArgs e) { int outerBrushColor = HelperMethods.ColorToWin32(m_outerColor); int innerBrushColor = HelperMethods.ColorToWin32(this.BackColor); IntPtr hdc = e.Graphics.GetHdc(); try { IntPtr hbrOuter = NativeMethods.CreateSolidBrush(outerBrushColor); IntPtr hOldBrush = NativeMethods.SelectObject(hdc, hbrOuter); NativeMethods.RoundRect(hdc, 0, 0, this.Width, this.Height, m_diametro, m_diametro); IntPtr hbrInner = NativeMethods.CreateSolidBrush(innerBrushColor); NativeMethods.SelectObject(hdc, hbrInner); NativeMethods.RoundRect(hdc, 0, 18, this.Width, this.Height, m_diametro, m_diametro); NativeMethods.SelectObject(hdc, hOldBrush); NativeMethods.DeleteObject(hbrOuter); NativeMethods.DeleteObject(hbrInner); } finally { e.Graphics.ReleaseHdc(hdc); } if (!string.IsNullOrEmpty(m_roundedGroupBoxText)) { Font titleFont = new Font("Tahoma", 9.0F, FontStyle.Bold); Brush titleBrush = new SolidBrush(this.BackColor); try { e.Graphics.DrawString(m_roundedGroupBoxText, titleFont, titleBrush, 14.0F, 2.0F); } finally { titleFont.Dispose(); titleBrush.Dispose(); } } base.OnPaint(e); } An the OnPaintBackground is: protected override void OnPaintBackground(PaintEventArgs e) { if (this.Parent != null) { SolidBrush backBrush = new SolidBrush(this.Parent.BackColor); try { e.Graphics.FillRectangle(backBrush, 0, 0, this.Width, this.Height); } finally { backBrush.Dispose(); } } } Thank you!

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  • Entity Framework 4 relationship management in POCO Templates - More lazy than FixupCollection?

    - by Joe Wood
    I've been taking a look at EF4 POCO templates in beta 2. The FixupCollection looks fine for maintaining the model correctness after updating the relationship collection property (i.e. product.Orders it would set the order.Product reference ). But what about support for handling the scenario when some of those Order objects are removed from the context? The use-case of maintaining cascading deletes in the in-memory model. The old Typed DataSet model used to do this by performing the query through the container to derive the relationship results. Like the DataSet, this would require a reference to the ObjectContext inside the entity class so that it could query the top-level Order collection. Better support for Separation of Concerns in the ObjectContext would be required. It looks like EF is not suited to this use-case that DataSets did out of the box.... am I right?

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  • How to clean-up an Entity Framework object context?

    - by Daniel Brückner
    I am adding several entities to an object context. try { forach (var document in documents) { this.Validate(document); // May throw a ValidationException. this.objectContext.AddToDocuments(document); } this.objectContext.SaveChanges(); } catch { // How to clean-up the object context here? throw; } If some of the documents pass the the validation and one fails, all documents that passed the validation remain added to the object context. I have to clean-up the object context because it may be reused and the following can happen. var documentA = new Document { Id = 1, Data = "ValidData" }; var documentB = new Document { Id = 2, Data = "InvalidData" }; var documentC = new Document { Id = 3, Data = "ValidData" }; try { // Adding document B will cause a ValidationException but only // after document A is added to the object context. this.DocumentStore.AddDocuments(new[] { documentA, documentB, documentC }); } catch (ValidationException) { } // Try again without the invalid document B. this.DocumentStore.AddDocuments(new[] { documentA, documentC }); This will again add document A to the object context and in consequence SaveChanges() will throw an exception because of a duplicate primary key. So I have to remove all already added documents in the case of an validation error. I could of course perform the validation first and only add all documents after they have been successfully validated. But sadly this does not solve the whole problem - if SaveChanges() fails all documents still remain add but unsaved. I tried to detach all objects returned by this.objectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Added) but I am getting a exception stating that the object is not attached. So how do I get rid of all added but unsaved objects?

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  • How do you model roles / relationships with Domain Driven Design in mind?

    - by kitsune
    If I have three entities, Project, ProjectRole and Person, where a Person can be a member of different Projects and be in different Project Roles (such as "Project Lead", or "Project Member") - how would you model such a relationship? In the database, I currently have the following tablers: Project, Person, ProjectRole Project_Person with PersonId & ProjectId as PK and a ProjectRoleId as a FK Relationship. I'm really at a loss here since all domain models I come up with seem to break some "DDD" rule. Are there any 'standards' for this problem? I had a look at a Streamlined Object Modeling and there is an example what a Project and ProjectMember would look like, but AddProjectMember() in Project would call ProjectMember.AddProject(). So Project has a List of ProjectMembers, and each ProjectMember in return has a reference to the Project. Looks a bit convoluted to me. update After reading more about this subject, I will try the following: There are distinct roles, or better, model relationships, that are of a certain role type within my domain. For instance, ProjectMember is a distinct role that tells us something about the relationship a Person plays within a Project. It contains a ProjectMembershipType that tells us more about the Role it will play. I do know for certain that persons will have to play roles inside a project, so I will model that relationship. ProjectMembershipTypes can be created and modified. These can be "Project Leader", "Developer", "External Adviser", or something different. A person can have many roles inside a project, and these roles can start and end at a certain date. Such relationships are modeled by the class ProjectMember. public class ProjectMember : IRole { public virtual int ProjectMemberId { get; set; } public virtual ProjectMembershipType ProjectMembershipType { get; set; } public virtual Person Person { get; set; } public virtual Project Project { get; set; } public virtual DateTime From { get; set; } public virtual DateTime Thru { get; set; } // etc... } ProjectMembershipType: ie. "Project Manager", "Developer", "Adviser" public class ProjectMembershipType : IRoleType { public virtual int ProjectMembershipTypeId { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } // etc... }

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  • How to design a command line program and keep it open for a future GUI?

    - by systempuntoout
    What are some best practices to keep in mind when developing a script program that could be integrated with a GUI, probably by somebody else, in the future? Example scenario: i develop a fancy python CLI program that scrapes every unicorn images from the web i decide to publish it on github a unicorn fan programmer decide to take the sources and build a GUI on them. he gives up because my code is a mess How do i avoid step 4 and let unicorn fan programmer build his GUI without hassle?

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  • Is it a good object-oriented-design practice to send a pointer to private data to another class?

    - by Denis
    Hello everyone, There is well known recommendation not to include into class interface method that returns a pointer (or a reference) to private data of the class. But what do you think about public method of a class that sends to another class a pointer to the private data of the first one. For example: class A { public: void fA(void) {_b.fB(&_var)}; private: B _b; int _var; }; I think that it is some sort of data hiding damage: the private data define state of their own class, so why should one class delegate changes of its own state to another one? What do you think? Denis

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  • Entity Framework - Merging 2 physical tables into one "virtual" table problems...

    - by Keith Barrows
    I have been reading up on porting ASP.NET Membership Provider into .NET 3.5 using LINQ & Entities. However, the DB model that every single sample shows is the newer model while I've inherited a rather old model. Differences: The User Table is split into a pair of User & Membership Tables. All of the tables in the DB are prepended with aspnet_ I have Lowered versions of some columns (UserName, Email, etc) To work with this I have copied the properties from the Membership table into the User table (in the DB this is a 1<-1 relationship, not a 1<-0,1), renamed aspnet_Applications to Application, aspnet_Profiles to Profile, aspnet_Users to User and aspnet_Roles to Role. (See image) Link to full size image of model Now, I am running into one of 2 problems when I try to compile. Using the model in the image I get this error: Problem in Mapping Fragment starting at line 464: EntitySets 'UserSet' and 'aspnet_Membership' are both mapped to table 'aspnet_Membership'. Their Primary Keys may collide. If I delete the aspnet_Membership table from my model (to handle the above error) I then get: Problem in Mapping Fragment starting at line 384: Column aspnet_Membership.ApplicationId in table aspnet_Membership must be mapped: It has no default value and is not nullable. My ability to hand edit the backing stores is not the best and I don't want to just hack something in that may break other things. I am looking for suggestions, best practices, etc to handle this. Note: Moving the data tables themselves is not an option as I cannot replace all the logic in the existing apps. I am building this EF Provider for a new App. Over the next 6 months the old app(s) will migrate bit-by-bit to the new structures. Note: I added a link just under the image to the full size image for better viewing.

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  • how does hash element make a secure login on zend framework?

    - by ulduz114
    hello all i saw a example for login form same blow code class Form_Login extends Zend_Form { //put your code here public function init($timeout=360){ $this->addElement('hash', 'token', array( 'timeout' => $timeout )); $this->setName('Login'); $username = $this->createElement ( 'text', 'username' ); $username->setLabel('user name:') ->setRequired(); $this->addElement($username); $password=$this->createElement('password','password'); $password->setLabel('password:'); $password->setRequired(); $this->addElement($password); $login=$this->createElement('submit','login'); $login->setLabel('Login'); $this->addElement($login); $this->setMethod('post'); $this->setAction(Zend_Controller_Front::getInstance()->getBaseUrl().'/authentication/login'); } } and in submitAction a part code same below if (!$form->isValid($request->getPost())) { if (count($form->getErrors('token')) > 0) { return $this->_forward('csrf-forbidden', 'error'); } $this->view->form = $form; return $this->render('login'); } now , my question, whats the reason for use of hash element? how this hash element make secure login? anybody may help explain these? thanks

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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  • How can I setup a simple custom route using Zend Framework's Zend_Application?

    - by Billy ONeal
    I'm looking to setup a custom route which supplies implicit parameter names to a Zend_Application. Essentially, I have an incoming URL which looks like this: /StandardSystems/Dell/LatitudeE6500 I'd like that to be mapped to the StandardsystemsController, and I'd like that controller to be passed parameters "make" => "Dell" and "model" => "LatitudeE6500". How can I setup such a system using Zend_Application?

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  • How do I get the entity framework to work with archive flags?

    - by Orion Adrian
    I'm trying to create a set of tables where we don't actually delete them, but rather we set the archive flags instead. When we delete an entity, it shouldn't be deleted, it should be marked as archived instead. What are the programming patterns to support this? I would also prefer not to have to roll out my own stored procs for every table that have these archive flags if there is another solution.

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  • Zend Framework - tinyMCE - plugin folders are mistaken to be controllers? Help

    - by Ali
    Hi guys I'm trying to integrate the tinymce plugin however I'm running into problems such that almost every feature which requires a plugin to be rendered i.e the add url popup or add image pop up - it opens an empty pop up window. Even if I try to open it inline I get the same blank popup window.. I noticed that whenever I click on lets say url button in tinymCE it opens with reference to my localhost and because of that I'm assuming my application is mistaking the containing javascript folder to be some controller or action. How can I fix this please - I've set up mod rewrite to allow clean urls as well as ignore the javascript folder but this is a different issue altogether :( what should I be looking at here.. I can't notice any error sin firebug..

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  • How to implement a left outer join in the Entity Framework.

    - by user206736
    I have the following SQL query:- select distinct * from dbo.Profiles profiles left join ProfileSettings pSet on pSet.ProfileKey = profiles.ProfileKey left join PlatformIdentities pId on pId.ProfileKey = profiles.Profilekey I need to convert it to a LinqToEntities expression. I have tried the following:- from profiles in _dbContext.ProfileSet let leftOuter = (from pSet in _dbContext.ProfileSettingSet select new { pSet.isInternal }).FirstOrDefault() select new { profiles.ProfileKey, Internal = leftOuter.isInternal, profiles.FirstName, profiles.LastName, profiles.EmailAddress, profiles.DateCreated, profiles.LastLoggedIn, }; The above query works fine because I haven't considered the third table "PlatformIdentities". Single left outer join works with what I have done above. How do I include PlatformIdentities (the 3rd table) ? I basically want to translate the SQL query I specified at the beginning of this post (which gives me exactly what I need) in to LinqToEntities. Thanks

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