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• Rails: find by day of week with timestamp

  - by Sleepycat

  I need to grab the records for same day of the week for the preceeding X days of the week. There must be a better way to do it than this: Transaction.find_by_sql "select * from transactions where EXTRACT(DOW from date) = 1 and organisation_id = 4 order by date desc limit 7" It gets me what I need but is Postgres specific and not very "Rails-y". Date is a timestamp. Anyone got suggestions?

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• Programming tips for writing document editors?

  - by Tesserex

  I'm asking this because I'm in the process of writing two such editors for my Mega Man engine, one a tileset editor, and another a level editor. When I say document editor, I mean the superset application type for things like image editors and text editors. All of these share things like toolbars, menu options, and in the case of image editors, and my apps, tool panes. We all know there's tons of advice out there for interface design in these apps, but I'm wondering about programming advice. Specifically, I'm doubting my code designs with the following things: Many menu options toggle various behaviors. What's the proper way to reliably tie the checked state of the option with the status of the behavior? Sometimes it's more complicated, like options being disabled when there's no document loaded. More and more consensus seems to be against using MDI, but how should I control tool panes? For example, I can't figure out how to get the panels to minimize and maximize along with the main window, like Photoshop does. When tool panels are responsible for a particular part of the document, who actually owns that thing? The main window, or the panel class? How do you do communication between the tool panels and the main window? Currently mine is all event based but it seems like there could be a better way. This seems to be a common class of gui application, but I've never seen specific pointers on code design for them. Could you please offer whatever advice or experience you have for writing them?

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• Is there a way to avoid debugger?

  - by Gabriel Šcerbák

  I don't like debugging in a debugger, because I think it is often below the abstraction layer of the programming language and it is often not reproducible. I favor usign unit tests when possible and I think they are a good way, but it is not always that easy to implement them. Do you know about any other alternative approaches to avoid the use of debugger?

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• where should we send notification for updating many views?

  - by Thanh-Cong Vo

  Hi all, I want to ask about software design. I have a task, the view controller handles UI event for calling a model manger to perform that task. After finishing, the model manager will callback to update the view. There have also other views who care about that task, and also want to update its own view when that task is finished. So I register a Notification for that task in each views. The problem is defining where should I send Notification, in Model manager or in the View who handles event and receives the callback from Model manager? What is better design? Shoud the model care about send this "common" task, or shoud the view? Thanks

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• Best practice when using WebMethods and session

  - by Abdel Olakara

  Hi all, I want to reduce postback in one of my application page and use ajax instead. I used the WebMethod to do so.. I have a static WebMethod that needs to access the session variables and modify. and on the client side, i am calling this method using jQuery. I tried accessing the session as follows: [WebMethod] public static void TestWebMethod() { if (HttpContext.Current.Session["pitems"] != null) { log.Debug("Using the existing list"); Product prod = (Product)HttpContext.Current.Session["pitems"]; List<Configs> confs = cart.GetConfigs(); foreach (Configs citem in confis) { log.Info(citem.Description); } } log.Info("Inside the method!"); } The values are displayed correctly and seems to work.. but i would like to know if this practice is allowed as the method is a static methods and would like to know how it will behave if multiple people access the application. I would also like to know how developers do these kind of tasks in ASP if this is not the right method. Thanks in advance for your suggestions and ideas, Abdel Olakara

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• Views performance in MySQL for denormalization

  - by Gianluca Bargelli

  I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role). EDIT Specifically what i'm trying to obtain is Denormalization of three tables into one. Is my solution correct? See Denormalization on wikipedia

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• effective retrieve for a voting system in PHP and MySQL

  - by Adnan

  Hello, I have a system where registered users can vote up/vote down comment for a picture. Something very similar to SO's voting system. I store the votes in a table with values as such; vote_id | vote_comment_id | vote_user_id | vote_date | vote_type Now I have few a question concerned the speed and efficiency for the following; PROB: Once a user opens the picture page with comments I need, if that user has already voted UP/DOWN a comment to show it like; "you voted up" or "you voted down" next to the comment (in SO it the vote image is highlighted) MY POSSIBLE SOL: Right now when I open a picture page for each comment I loop thru, I loop thru my table of votes as well and check if a user has voted and show the status (I compare the vote_user_id with the user's session). How efficient is this? Anyone have a better approach to tackle this kind of problem?

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• Factory Pattern - when do you say you need a specialised factory

  - by dbones

  Hi, I am having a little design crisis, I am making a Plane class, which is made of an engine 2 wings and N seats The engine takes in a engine size, and the wings have a span. would this still be feasible to have a PlaneFactory, when the factory may have to take in multiple parameters to setup the plane (wings, engine, no of seats) thanks in advance bones

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• When to use a routing rule vs query string parameters with asp.net mvc

  - by mwright

  We're considering moving forward with a ASP.NET MVC project and the subject of routing versus parameters came up. Seeing as how you can easily set up either or a combination of both in ASP.NET MVC, are there any considerations that I should be aware of when using one or the other?

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• Should I store generated code in source control

  - by Ron Harlev

  This is a debate I'm taking a part in. I would like to get more opinions and points of view. We have some classes that are generated in build time to handle DB operations (in This specific case, with SubSonic, but I don't think it is very important for the question). The generation is set as a pre-build step in Visual Studio. So every time a developer (or the official build process) runs a build, these classes are generated, and then compiled into the project. Now some people are claiming, that having these classes saved in source control could cause confusion, in case the code you get, doesn't match what would have been generated in your own environment. I would like to have a way to trace back the history of the code, even if it is usually treated as a black box. Any arguments or counter arguments? UPDATE: I asked this question since I really believed there is one definitive answer. Looking at all the responses, I could say with high level of certainty, that there is no such answer. The decision should be made based on more than one parameter. Reading the answers below could provide a very good guideline to the types of questions you should be asking yourself when having to decide on this issue. I won't select an accepted answer at this point for the reasons mentioned above.

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• Looking for exercises to learn SQL, using the Northwind database

  - by MedicineMan

  I am trying to become more familiar with SQL by writing queries against the Northwind database. I am looking for some exercises that would help me to learn SQL and features of SQL Server. It is important that the exercises have solutions, and in complicated cases, it would be great if there was an explanation for the query. Thanks for the answers so far but I still have not found what I am looking for: Is there any free resource, available online, without registration, that I can find a list of these exercises?

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• How to skip callbacks on Mongoid Documents?

  - by jpemberthy

  My question is similar to this one http://stackoverflow.com/questions/1342761/how-to-skip-activerecord-callbacks but instead of AR I'm using Mongoid, It seems like that isn't implemented yet in the current version of Mongoid, so I'd like to know what should be an elegant solution to implement it. (if necessary).

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• Normalize or Denormalize in high traffic websites

  - by Inam Jameel

  what is the best practice for database design for high traffic websites like this one stackoverflow? should one must use normalize database for record keeping or normalized technique or combination of both? is it sensible to design normalize database as main database for record keeping to reduce redundancy and at the same time maintain another denormalized form of database for fast searching? or main database should be denormalize and one can make normalized views in the application level for fast database operations? or beside above mentioned approach? what is the best practice of designing high traffic websites???

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• Create inherited class from base class

  - by Raj

  public class Car { private string make; private string model; public Car(string make, string model) { this.make = make; this.model = model; } public virtual void Display() { Console.WriteLine("Make: {0}", make); Console.WriteLine("Model: {0}", model); } public string Make { get{return make;} set{make = value;} } public string Model { get{return model;} set{model = value;} } } public class SuperCar:Car { private Car car; private int horsePower; public SuperCar(Car car) { this.car = car; } public int HorsePower { get{return horsePower;} set{horsepower = value;} } public override void Display() { base.Display(); Console.WriteLine("I am a super car"); } When I do something like Car myCar = new Car("Porsche", "911"); SuperCar mySupcar = new SuperCar(myCar); mySupcar.Display(); I only get "I am a supercar" but not the properties of my base class. Should I explicitly assign the properties of my base class in the SuperCar constructor? In fact I'm trying Decorator pattern where I want a class to add behaviour to a base class.

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• CSS selectors : should I make my CSS easier to read or optimise the speed

  - by Laurent Bourgault-Roy

  As I was working on a small website, I decided to use the PageSpeed extension to check if their was some improvement I could do to make the site load faster. However I was quite surprise when it told me that my use of CSS selector was "inefficient". I was always told that you should keep the usage of the class attribute in the HTML to a minimum, but if I understand correctly what PageSpeed tell me, it's much more efficient for the browser to match directly against a class name. It make sense to me, but it also mean that I need to put more CSS classes in my HTML. It make my .css file harder to read. I usually tend to mark my CSS like this : #mainContent p.productDescription em.priceTag { ... } Which make it easy to read : I know this will affect the main content and that it affect something in a paragraph tag (so I wont start to put all sort of layout code in it) that describe a product and its something that need emphasis. However it seem I should rewrite it as .priceTag { ... } Which remove all context information about the style. And if I want to use differently formatted price tag (for example, one in a list on the sidebar and one in a paragraph), I need to use something like that .paragraphPriceTag { ... } .listPriceTag { ... } Which really annoy me since I seem to duplicate the semantic of the HTML in my classes. And that mean I can't put common style in an unqualified .priceTag { ... } and thus I need to replicate the style in both CSS rule, making it harder to make change. (Altough for that I could use multiple class selector, but IE6 dont support them) I believe making code harder to read for the sake of speed has never been really considered a very good practice . Except where it is critical, of course. This is why people use PHP/Ruby/C# etc. instead of C/assembly to code their site. It's easier to write and debug. So I was wondering if I should stick with few CSS classes and complex selector or if I should go the optimisation route and remove my fancy CSS selectors for the sake of speed? Does PageSpeed make over the top recommandation? On most modern computer, will it even make a difference?

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• Hyphens or underscores in CSS and HTML identifiers?

  - by Török Gábor

  As both hyphen (-) and underscore (_) are valid characters in CSS and HTML identifiers, what are the advantages and disadvantages using one or the other? I prefer writing CSS class names with hyphens (e.g. field-text) and underscores for IDs (e.g. featured_content). Is there a best practice or it's only the matter of taste?

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• What is your strategy to avoid dynamic typing errors in Python (NoneType has no attribute x)?

  - by Koen Bok

  Python is one of my favorite languages, but I really have a love/hate relationship with it's dynamicness. Apart from the advantages, it often results in me forgetting to check a type, trying to call an attribute and getting the NoneType (or any other) has no attribute x error. A lot of them are pretty harmless but if not handled correctly they can bring down your entire app/process/etc. Over time I got better predicting where these could pop up and adding explicit type checking, but because I'm only human I miss one occasionally and then some end-user finds it. So I'm interested in your strategy to avoid these. Do you use type-checking decorators? Maybe special object wrappers? Please share...

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• where to enlist transaction with parent child delete (repository or bll)?

  - by Caroline Showden

  My app uses a business layer which calls a repository which uses linq to sql. I have an Item class that has an enum type property and an ItemDetail property. I need to implement a delete method that: (1) always delete the Item (2) if the item.type is XYZ and the ItemDetail is not null, delete the ItemDetail as well. My question is where should this logic be housed? If I have it in my business logic which I would prefer, this involves two separate repository calls, each of which uses a separate datacontext. I would have to wrap both calls is a System.Transaction which (in sql 2005) get promoted to a distributed transaction which is not ideal. I can move it all to a single repository call and the transaction will be handled implicitly by the datacontext but feel that this is really business logic so does not belong in the repository. Thoughts? Carrie

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• GAE modeling relationship options

  - by Sway

  Hi there, I need to model the following situation and I can't seem to find a consistent example on how to do it "correctly" for the google app engine. Suppose I've got a simple situation like the following: [Company] 1 ----- M [Stare] A company has one to many stores. Each store has an address made up of a address line 1, city, state, country, postcode etc. Ok. Lets say we need to create say an "Audit". An Audit is for a company and can be across one to many stares. So something like: [Audit] 1 ------ 1 [Company] 1 ------ M [Store] Now we need to query all of the "audits" based on the Store "addresses" in order to send the "Auditors" to the right locations. There seem to be numerous articles like this one: http://code.google.com/appengine/articles/modeling.html Which give examples of creating a "ContactCompany" model class. However they also say that you should use this kind of relationship only when you "really need to" and with "care" for performance. I've also read - frequently - that you should denormalize as much as possible thereby moving all of the "query-able" data into the Audit class. So what would you suggest as the best way to solve this? I've seen that there is an Expando class but I'm not sure if that is the "best" option for this. Any help or thoughts on this would be totally appreciated. Thanks in advance, Matt

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• Best practice No1: inline search layout across browsers

  - by Sixfoot Studio

  Ok, I have managed to fix my version of this example using a multitude of hacks and I would like to see how others would tackle this problem making this cross-browser compatible without too many hacks. <div class="searchDiv"> <img src="Images/left.gif" class="left" height="19" width="3" /> <input id="TextBox" type="text" class="searchField" /> <img src="Images/right.gif" height="19"width="3" class="right" /> <a href="" class="submit">Submit</a> <img src="Images/box-arrow.gif" class="linkArrow" width="8" height="14" /> </div> I am using a Transitional DTD in my example. Based on the everyone else's CSS examples, comments and answers I will make the final vote. I'd love to see more of these scenarios come up so that people have a library of "best practice" methods which they can find on SO. Good luck

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• C++, throw exception from initializer list

  - by aaa

  hello. what is the best way to throw exception from initializer list? for example: class C { T0 t0; // can be either valid or invalid, but does not throw directly T1 t1; // heavy object, do not construct if t0 is invalid, by throwing before C(int n) : t0(n), // throw exception if t0(n) is not valid t1() {} }; I thought maybe making wrapper, e.g. t0(throw_if_invalid(n)). What is the practice to handle such cases? Thanks

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• Spring MVC Best Practice Handling Unrecoverable Exceptions In Controller

  - by jboyd

  When you have a controller that does logic with services and DAO's that may throw an unrecoverable exception, what is the best practice in dealing with those method calls? Currently an app I'm working on has very lengthy try catch methods that simply err.out exception messages, this doesn't seem very robust and I think that this code smells, is there any cookie cutter best practice for handling this in spring-mvc?

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• Example with Visitor Pattern

  - by devoured elysium

  public class Song { public string Genre { get; protected set; } public string Name { get; protected set; } public string Band { get; protected set; } public Song(string name, string band, string genre) { Name = name; Genre = genre; Band = band; } } public interface IMusicVisistor { void Visit(List<Song> items); } public class MusicLibrary { List<Song> _songs = new List<Song> { ...songs ... }; public void Accept(IMusicVisitor visitor) { visitor.Visit(_songs); } } and now here's one Visitor I made: public class RockMusicVisitor : IMusicVisitor { public List<Song> Songs { get; protected set; } public void Visit(List<Song> items) { Songs = items.Where(x => x.Genre == "Rock").ToList(); } } Why is this any better than just putting a public property Songs and then letting any kind of class do with it anything that it wants to? This example comes from this post.

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• Best Practice for Uploading Many (2000+) Images to A Server

  - by bob

  Hello, I have a general question about this. When you have a gallery, sometimes people need to upload 1000's of images at once. Most likely, it would be done through a .zip file. What is the best way to go about uploading this sort of thing to a server. Many times, server have timeouts etc. that need to be accounted for. I am wondering what kinds of things should I be looking out for and what is the best way to handle a large amount of images being uploaded. I'm guessing that you would allow a user to upload a zip file (assuming the timeout does not effect you), and this zip file is uploaded to a specific directory, lets assume in this case a directory is created for each user in the system. You would then unzip the directory on the server and scan the user's folder for any directories containing .jpg or .png or .gif files (etc.) and then import them into a table accordingly. I'm guessing labeled by folder name. What kind of server side troubles could I run into? I'm aware that there may be many issues. Even general ideas would be could so I can then research further. Thanks! Also, I would be programming in Ruby on Rails but I think this question applies accross any language.

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• How to use references, avoid header bloat, and delay initialization?

  - by Kyle

  I was browsing for an alternative to using so many shared_ptrs, and found an excellent reply in a comment section: Do you really need shared ownership? If you stop and think for a few minutes, I'm sure you can pinpoint one owner of the object, and a number of users of it, that will only ever use it during the owner's lifetime. So simply make it a local/member object of the owners, and pass references to those who need to use it. I would love to do this, but the problem becomes that the definition of the owning object now needs the owned object to be fully defined first. For example, say I have the following in FooManager.h: class Foo; class FooManager { shared_ptr<Foo> foo; shared_ptr<Foo> getFoo() { return foo; } }; Now, taking the advice above, FooManager.h becomes: #include "Foo.h" class FooManager { Foo foo; Foo& getFoo() { return foo; } }; I have two issues with this. First, FooManager.h is no longer lightweight. Every cpp file that includes it now needs to compile Foo.h as well. Second, I no longer get to choose when foo is initialized. It must be initialized simultaneously with FooManager. How do I get around these issues?

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