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  • Is there a function similar to Math.Max for Entity Framework?

    - by Ryan ONeill
    I have an entity framework query as follows; From T In Db.MyTable Where (T.Col1 - T.Col2) + T.Col3 - T.Col4 > 0 _ Select T I now need to make sure that the bracketed part '(T.Col1 - T.Col2)' does not go below zero. In .Net, I'd code it as follows (but obviously EF does not like Math.Max). From T In Db.MyTable Where Math.Max(T.Col1 - T.Col2,0) + T.Col3 - T.Col4 > 0 _ Select T Is there an easy way to do this? I am using EF 2.0 (not the latest, just released version). Thanks in advance

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  • C# / Entity Framework / Linq question regarding calling a method when a class is accessed...

    - by Daniel
    So this is probably really basic, but I'm fairly new to all this. I am using Entity Framework with POCO entities. I want to call a method when a class property is set. I am trying to build an advertisement platform. I have a Customer class, a Venue class and an Advertisement class. I have my indexes set up in such a way that I can call customer.venue. However, I want to be able to call Customer.Venue.CurrentAdvertisement and have it execute a method (if CurrentAdvertisement is null) and return the current advertisement. I know I can explicitly set it every time, but I want to be able to override my classes so that whenever the CurrentAdvertisement property is accessed via LINQ it runs that method to return an ad. In order to do this I need to pass the Venue class a variable (venue name).

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  • Can't update rows in my database using Entity Framework...?

    - by Dissonant
    Okay, this is really weird. I made a simple database with a single table, Customer, which has a single column, Name. From the database I auto-generated an ADO.NET Entity Data Model, and I'm trying to add a new Customer to it like so: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Test { class Program { static void Main() { Database1Entities db = new Database1Entities(); Customer c = new Customer(); c.Name = "Harry"; db.AddToCustomer(c); db.SaveChanges(); } } } But it doesn't persist Customer "Harry" to the database! I've been scratching my head for a while now wondering why such a simple operation doesn't work. What on earth could be the problem!?

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  • How do I tell Entity Framework that a column in a view is nullable?

    - by Ryan ONeill
    I have a view which has an Int column which is nullable (let's call it StackOverflowCount). When generating an EF model from the database, the EF designer does not recognise it as nullable and creates the column as an Int. The issue I have is that on the EF designer I have set the column to Nullable and the following error then kills the compilation; Error 3031: Problem in mapping fragments starting at line 2327: Non-nullable column MyView.StackOverflowCount in table MyView is mapped to a nullable entity property. I can get round this by opening the .edmx file in XML mode and manually editing the SQL column definition, but there is no way to do this using the designer and it gets overwritten the next time I refresh from the model from the DB. Is this 'by design' or an example of something that slipped through into EF 4.0? I'm using .Net 4.0 with EF 4.0 under VS 2010.

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  • How do I delete an object from an Entity Framework model without first loading it?

    - by Tomas Lycken
    I am quite sure I've seen the answer to this question somewhere, but as I couldn't find it with a couple of searches on SO or google, I ask it again anyway... In Entity Framework, the only way to delete a data object seems to be MyEntityModel ent = new MyEntityModel(); ent.DeleteObject(theObjectToDelete); ent.SaveChanges(); However, this approach requires the object to be loaded to, in this case, the Controller first, just to delete it. Is there a way to delete a business object referencing only for instance its ID? If there is a smarter way using Linq or Lambda expressions, that is fine too. The main objective, though, is to avoid loading data just to delete it.

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  • Should i use partial classes as business layer when using entity framework?

    - by samsur
    I am working on a project using entity framework. Is it okay to use partial classes of the EF generated classes as the business layer. I am begining to think that this is how EF is intended to be used. I have attempted to use a DTO pattern and soon realized that i am just creating a bunch of mapping classes that is duplicating my effort and also a cause for more maintenance work and an additional layer. I want to use self-tracking-entities and pass the EF entities to all the layers. Please share your thoughts and ideas. Thanks

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  • Is LocalDB supported by Visual Studio 2010 in Entity Framework 5?

    - by Mathias Lykkegaard Lorenzen
    Is LocalDB supported by Visual Studio 2010 in Entity Framework 5, on .NET 4.0? Or am I doing it wrong? I'm getting a "The network path can't be found" issue when instantiating my model container with a connection string for LocalDB. Here's the connection string: var connectionString = "metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;provider=System.Data.SqlClient;provider connection string=\"data source=(localdb)\v11.0;initial catalog=fablelane_com_db;integrated security=SSPI;multipleactiveresultsets=True;App=EntityFramework\""; Edit 1 I'm receiving the following error when connecting, more specifically: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server). Edit 2 I just figured out that changing to Visual Studio 11 beta doesn't work either. Still receiving the same error-message.

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  • Abstracting entity caching in XNA

    - by Grofit
    I am in a situation where I am writing a framework in XNA and there will be quite a lot of static (ish) content which wont render that often. Now I am trying to take the same sort of approach I would use when doing non game development, where I don't even think about caching until I have finished my application and realise there is a performance problem and then implement a layer of caching over whatever needs it, but wrap it up so nothing is aware its happening. However in XNA the way we would usually cache would be drawing our objects to a texture and invalidating after a change occurs. So if you assume an interface like so: public interface IGameComponent { void Update(TimeSpan elapsedTime); void Render(GraphicsDevice graphicsDevice); } public class ContainerComponent : IGameComponent { public IList<IGameComponent> ChildComponents { get; private set; } // Assume constructor public void Update(TimeSpan elapsedTime) { // Update anything that needs it } public void Render(GraphicsDevice graphicsDevice) { foreach(var component in ChildComponents) { // draw every component } } } Then I was under the assumption that we just draw everything directly to the screen, then when performance becomes an issue we just add a new implementation of the above like so: public class CacheableContainerComponent : IGameComponent { private Texture2D cachedOutput; private bool hasChanged; public IList<IGameComponent> ChildComponents { get; private set; } // Assume constructor public void Update(TimeSpan elapsedTime) { // Update anything that needs it // set hasChanged to true if required } public void Render(GraphicsDevice graphicsDevice) { if(hasChanged) { CacheComponents(graphicsDevice); } // Draw cached output } private void CacheComponents(GraphicsDevice graphicsDevice) { // Clean up existing cache if needed var cachedOutput = new RenderTarget2D(...); graphicsDevice.SetRenderTarget(renderTarget); foreach(var component in ChildComponents) { // draw every component } graphicsDevice.SetRenderTarget(null); } } Now in this example you could inherit, but your Update may become a bit tricky then without changing your base class to alert you if you had changed, but it is up to each scenario to choose if its inheritance/implementation or composition. Also the above implementation will re-cache within the rendering cycle, which may cause performance stutters but its just an example of the scenario... Ignoring those facts as you can see that in this example you could use a cache-able component or a non cache-able one, the rest of the framework needs not know. The problem here is that if lets say this component is drawn mid way through the game rendering, other items will already be within the default drawing buffer, so me doing this would discard them, unless I set it to be persisted, which I hear is a big no no on the Xbox. So is there a way to have my cake and eat it here? One simple solution to this is make an ICacheable interface which exposes a cache method, but then to make any use of this interface you would need the rest of the framework to be cache aware, and check if it can cache, and to then do so. Which then means you are polluting and changing your main implementations to account for and deal with this cache... I am also employing Dependency Injection for alot of high level components so these new cache-able objects would be spat out from that, meaning no where in the actual game would they know they are caching... if that makes sense. Just incase anyone asked how I expected to keep it cache aware when I would need to new up a cachable entity.

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  • Can I use a single DateTime field on the Entity Framework model side when the value is stored in a set of Int fields in the actual database?

    - by Ivan
    The actual table in the database has separate integer fields for storing year, month, day, hour and minute values (all in UTC) (seconds and milliseconds are irrelevant for my task and considered equal to zero). Needless to say it would be of great convenience to have just one field of DateTime type on the application side and hide all the conversion under the cover of the Entity Framework model code. Any directions on how to do that? I am not very experienced with Entity Framework yet.

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  • Add child to existing parent record in entity framework.

    - by Shawn Mclean
    My relationship between the parent and child is that they are connected by an edge. It is similiar to a directed graph structure. DAL: public void SaveResource(Resource resource) { context.AddToResources(resource); //Should also add children. context.SaveChanges(); } public Resource GetResource(int resourceId) { var resource = (from r in context.Resources .Include("ToEdges").Include("FromEdges") where r.ResourceId == resourceId select r).SingleOrDefault(); return resource; } Service: public void AddChildResource(int parentResourceId, Resource childResource) { Resource parentResource = repository.GetResource(parentResourceId); ResourceEdge inEdge = new ResourceEdge(); inEdge.ToResource = childResource; parentResource.ToEdges.Add(inEdge); repository.SaveResource(parentResource); } Error: An object with the same key already exists in the ObjectStateManager. The existing object is in the Unchanged state. An object can only be added to the ObjectStateManager again if it is in the added state. Image: I have been told this is the sequence in submitting a child to an already existing parent: Get parent - Attach Child to parent - submit parent. That is the sequence I used. The code above is extracted from an ASP.NET MVC 2 application using the repository pattern.

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  • CoreData many-to-many relationship NSPredicate Exceptions

    - by user307550
    I'm trying to model a Person/Team relationship. It's a many to many relationship since a person can belong to multiple teams and a team can have multiple people. As suggested by the doc I created an intermediate entity called TeamMember. I am now trying to run a query to see if I have a list of people, whether a pre-existing Team already exists for them so I'm not storing duplicate Teams in the database NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Team" inManagedObjectContext:[pm managedObjectContext]]; [request setEntity:entity]; NSPredicate *predicate = nil; predicate = [NSPredicate predicateWithFormat:@"ALL %K IN %@", @"teamMembers.person", players]; players is an NSSet of people that I'm trying to search I'm getting the following exception: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unsupported predicate ALL teamMembers.person IN { (entity: Person; id: 0x1334470 ; data: { Ideally I would like them to match exactly and not just do an IN as well. Any help would be greatly appreciated

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  • Which is the good way to update object in EF6

    - by TrieuH
    I have searched and find 2 way to update object in EF var attachedEntity = _context.EntityClasses.Local.First(t => t.Id == entity.Id); //We have it in the context, need to update. if (attachedEntity != null) { var attachedEntry = _context.Entry(attachedEntity); attachedEntry.CurrentValues.SetValues(entity); } else { ////If it's not found locally, we can attach it by setting state to modified. ////This would result in a SQL update statement for all fields ////when SaveChanges is called. var entry = _context.Entry(entity); entry.State = EntityState.Modified; } _context.SaveChanges(); And other way is seem more easy var entity = _context.EntityClasses.FirstOrDefault(t => t.Id == entity.Id); _context.Entry(entity ).EntityState.Modified _context.SaveChanges(); What is best way to update object? NOTE: the performence is importance with me

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  • Blazing fast performance with RadGridView for WPF 4.0 and Entity Framework 4.0

    Just before our upcoming release of Q1 2010 SP1 (early next week), Ive decided to check how RadGridView for WPF will handle complex Entity Framework 4.0 query with almost 2 million records: public class MyDataContext{    IQueryable _Data;    public IQueryable Data    {        get        {            if (_Data == null)            {                var northwindEntities = new NorthwindEntities();                var queryable = from o in northwindEntities.Orders                               from od in northwindEntities.Order_Details                                select new                                {                                    od.OrderID,                                    od.ProductID,                                    od.UnitPrice,                                    od.Quantity,                                    od.Discount,                                    o.CustomerID,                                    o.EmployeeID,                                    o.OrderDate                                };                _Data = queryable.OrderBy(i => i.OrderID);            }             return _Data;        }    }} The grid is bound completely codeless in XAML using RadDataPager with PageSize set to 50: <Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" Title="MainWindow" mc...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Creating an ASP.NET report using Visual Studio 2010 - Part 1

    - by rajbk
    This tutorial walks you through creating an report based on the Northwind sample database. You will add a client report definition file (RDLC), create a dataset for the RDLC, define queries using LINQ to Entities, design the report and add a ReportViewer web control to render the report in a ASP.NET web page. The report will have a chart control. Different results will be generated by changing filter criteria. At the end of the walkthrough, you should have a UI like the following.  From the UI below, a user is able to view the product list and can see a chart with the sum of Unit price for a given category. They can filter by Category and Supplier. The drop downs will auto post back when the selection is changed.  This demo uses Visual Studio 2010 RTM. This post is split into three parts. The last part has the sample code attached. Creating an ASP.NET report using Visual Studio 2010 - Part 2 Creating an ASP.NET report using Visual Studio 2010 - Part 3   Lets start by creating a new ASP.NET empty web application called “NorthwindReports” Creating the Data Access Layer (DAL) Add a web form called index.aspx to the root directory. You do this by right clicking on the NorthwindReports web project and selecting “Add item..” . Create a folder called “DAL”. We will store all our data access methods and any data transfer objects in here.   Right click on the DAL folder and add a ADO.NET Entity data model called Northwind. Select “Generate from database” and click Next. Create a connection to your database containing the Northwind sample database and click Next.   From the table list, select Categories, Products and Suppliers and click next. Our Entity data model gets created and looks like this:    Adding data transfer objects Right click on the DAL folder and add a ProductViewModel. Add the following code. This class contains properties we need to render our report. public class ProductViewModel { public int? ProductID { get; set; } public string ProductName { get; set; } public System.Nullable<decimal> UnitPrice { get; set; } public string CategoryName { get; set; } public int? CategoryID { get; set; } public int? SupplierID { get; set; } public bool Discontinued { get; set; } } Add a SupplierViewModel class. This will be used to render the supplier DropDownlist. public class SupplierViewModel { public string CompanyName { get; set; } public int SupplierID { get; set; } } Add a CategoryViewModel class. public class CategoryViewModel { public string CategoryName { get; set; } public int CategoryID { get; set; } } Create an IProductRepository interface. This will contain the signatures of all the methods we need when accessing the entity model.  This step is not needed but follows the repository pattern. interface IProductRepository { IQueryable<Product> GetProducts(); IQueryable<ProductViewModel> GetProductsProjected(int? supplierID, int? categoryID); IQueryable<SupplierViewModel> GetSuppliers(); IQueryable<CategoryViewModel> GetCategories(); } Create a ProductRepository class that implements the IProductReposity above. The methods available in this class are as follows: GetProducts – returns an IQueryable of all products. GetProductsProjected – returns an IQueryable of ProductViewModel. The method filters all the products based on SupplierId and CategoryId if any. It then projects the result into the ProductViewModel. GetSuppliers() – returns an IQueryable of all suppliers projected into a SupplierViewModel GetCategories() – returns an IQueryable of all categories projected into a CategoryViewModel  public class ProductRepository : IProductRepository { /// <summary> /// IQueryable of all Products /// </summary> /// <returns></returns> public IQueryable<Product> GetProducts() { var dataContext = new NorthwindEntities(); var products = from p in dataContext.Products select p; return products; }   /// <summary> /// IQueryable of Projects projected /// into the ProductViewModel class /// </summary> /// <returns></returns> public IQueryable<ProductViewModel> GetProductsProjected(int? supplierID, int? categoryID) { var projectedProducts = from p in GetProducts() select new ProductViewModel { ProductID = p.ProductID, ProductName = p.ProductName, UnitPrice = p.UnitPrice, CategoryName = p.Category.CategoryName, CategoryID = p.CategoryID, SupplierID = p.SupplierID, Discontinued = p.Discontinued }; // Filter on SupplierID if (supplierID.HasValue) { projectedProducts = projectedProducts.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { projectedProducts = projectedProducts.Where(a => a.CategoryID == categoryID); }   return projectedProducts; }     public IQueryable<SupplierViewModel> GetSuppliers() { var dataContext = new NorthwindEntities(); var suppliers = from s in dataContext.Suppliers select new SupplierViewModel { SupplierID = s.SupplierID, CompanyName = s.CompanyName }; return suppliers; }   public IQueryable<CategoryViewModel> GetCategories() { var dataContext = new NorthwindEntities(); var categories = from c in dataContext.Categories select new CategoryViewModel { CategoryID = c.CategoryID, CategoryName = c.CategoryName }; return categories; } } Your solution explorer should look like the following. Build your project and make sure you don’t get any errors. In the next part, we will see how to create the client report definition file using the Report Wizard.   Creating an ASP.NET report using Visual Studio 2010 - Part 2

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  • EFMVC Migrated to .NET 4.5, Visual Studio 2012, ASP.NET MVC 4 and EF 5 Code First

    - by shiju
    I have just migrated my EFMVC app from .NET 4.0 and ASP.NET MVC 4 RC to .NET 4.5, ASP.NET MVC 4 RTM and Entity Framework 5 Code First. In this release, the EFMVC solution is built with Visual Studio 2012 RTM. The migration process was very smooth and did not made any major changes other than adding simple unit tests with NUnit and Moq. I will add more unit tests on later and will also modify the existing solution. Source Code You can download the source code from http://efmvc.codeplex.com/

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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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  • Is it possible to store ObjectContext on the client when using WCF and Entity Framework?

    - by Sergey
    Hello, I have a WCF service which performs CRUD operation on my data model: Add, Get, Update and Delete. And I'm using Entity Framework for my data model. On the other side there is a client application which calls methods of the WCF service. For example I have a Customer class: [DataContract] public class Customer { public Guid CustomerId {get; set;} public string CustomerName {get; set;} } and WCF service defines this method: public void AddCustomer(Customer c) { MyEntities _entities = new MyEntities(); _entities.AddToCustomers(c); _entities.SaveChanges(); } and the client application passes objects to the WCF service: var customer = new Customer(){CustomerId = Guid.NewGuid, CustomerName="SomeName"}; MyService svc = new MyService(); svc.Add(customer); // or svc.Update(customer) for example But when I need to pass a great amount of objects to the WCF it could be a perfomance issue because of I need to create ObjectContext each time when I'm doing Add(), Update(), Get() or Delete(). What I'm thinking on is to keep ObjectContext on the client and pass ObjectContext to the wcf methods as additional parameter. Is it possible to create and keep ObjectContext on the client and don't recreate it for each operation? If it is not, how could speed up the passing of huge amount of data to the wcf service? Sergey

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  • How do I add ROW_NUMBER to a LINQ query or Entity?

    - by Whozumommy
    I'm stumped by this easy data problem. I'm using the Entity framework and have a database of products. My results page returns a paginated list of these products. Right now my results are ordered by the number of sales of each product, so my code looks like this: return Products.OrderByDescending(u => u.Sales.Count()); This returns an IQueryable dataset of my entities, sorted by the number of sales. I want my results page to show the rank of each product (in the dataset). My results should look like this: Page #1 1. Bananas 2. Apples 3. Coffee Page #2 4. Cookies 5. Ice Cream 6. Lettuce I'm expecting that I just want to add a column in my results using the SQL ROW_NUMBER variable...but I don't know how to add this column to my results datatable. My resulting page does contain a foreach loop, but since I'm using a paginated set I'm guessing using that number to fake a ranking number would NOT be the best approach. So my question is, how do I add a ROW_NUMBER column to my query results in this case?

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  • What is the best way in assigning foreign key when using entity framework & LINQ to Entities?

    - by Abdel Olakara
    Hi all, I need to know the best practice of creating an entity object and assigning the foreign key. Here is my scenario. I have a Product table with pid,name,unit_price etc.. I also have a Rating table with pid (foregin key),rate,votes etc... Currently i am doing the following to create the rating object: var prod = entities.Product.First(p => p.product_id == pid); prod.Rating.Load(); if (prod.Rating != null) { log.Info("Rating already exists!"); // set values and Calcuate the score } else { log.Info("New Rating!!!"); Rating rating = new Rating(); // set values and do inital calculation prod.Rating = rating; } entities.SaveChanges(); Even though this works fine, i would like to know the best practice in doing these kind of assignment. Thanks for your suggestions and info. Best Regards, Abdel Olakara

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  • Another question about handling game states

    - by Eva
    I'm making a game designed with the entity-component paradigm that uses systems to communicate between components as explained here. I've reached the point in my development that I need to add game states (such as paused, playing, level start, round start, game over, etc.), but I'm not sure how to do it with my framework. I've looked at this code example on game states which everyone seems to reference, but I don't think it fits with my framework. It seems to have each state handling its own drawing and updating. My framework has a SystemManager that handles all the updating using systems. For example, here's my RenderingSystem class: public class RenderingSystem extends GameSystem { private GameView gameView_; /** * Constructor * Creates a new RenderingSystem. * @param gameManager The game manager. Used to get the game components. */ public RenderingSystem(GameManager gameManager) { super(gameManager); } /** * Method: registerGameView * Registers gameView into the RenderingSystem. * @param gameView The game view registered. */ public void registerGameView(GameView gameView) { gameView_ = gameView; } /** * Method: triggerRender * Adds a repaint call to the event queue for the dirty rectangle. */ public void triggerRender() { Rectangle dirtyRect = new Rectangle(); for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); dirtyRect.add(graphicsComponent.getDirtyRect()); } gameView_.repaint(dirtyRect); } /** * Method: renderGameView * Renders the game objects onto the game view. * @param g The graphics object that draws the game objects. */ public void renderGameView(Graphics g) { for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); if (!graphicsComponent.isVisible()) continue; GraphicsComponent.Shape shape = graphicsComponent.getShape(); BoundsComponent boundsComponent = object.getComponent(BoundsComponent.class); Rectangle bounds = boundsComponent.getBounds(); g.setColor(graphicsComponent.getColor()); if (shape == GraphicsComponent.Shape.RECTANGULAR) { g.fill3DRect(bounds.x, bounds.y, bounds.width, bounds.height, true); } else if (shape == GraphicsComponent.Shape.CIRCULAR) { g.fillOval(bounds.x, bounds.y, bounds.width, bounds.height); } } } /** * Method: getRenderableObjects * @return The renderable game objects. */ private HashSet<GameObject> getRenderableObjects() { return gameManager.getGameObjectManager().getRelevantObjects( getClass()); } } Also all the updating in my game is event-driven. I don't have a loop like theirs that simply updates everything at the same time. I like my framework because it makes it easy to add new GameObjects, but doesn't have the problems some component-based designs encounter when communicating between components. I would hate to chuck it just to get pause to work. Is there a way I can add game states to my game without removing the entity-component design? Does the game state example actually fit my framework, and I'm just missing something?

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  • How can I achieve strong typing with a component messaging system?

    - by Vaughan Hilts
    I'm looking at implementing a messaging system in my entity component system. I've deduced that I can use an event / queue for passing messages, but right now, I just use a generic object and cast out the data I want. I also considered using a dictionary. I see a lot of information on this, but they all involve a lot of casting and guessing. Is there any way to do this elegantly and keep strong typing on my messages?

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  • How can I efficiently update only the entities that matter in a given frame?

    - by lezebulon
    I'm making a RTS, which can potentially have lots of units in one map (think Age of Empires). I'm looking for a way to update my units. I want to avoid calling a virtual Update() method every frame on every entity. On the other hand, units that are not in view should still be updated and behave "normally." I'm assuming this is a fairly standard question; what would be a way to handle this situation?

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  • Why does the entity framework need an ICollection for lazy loading?

    - by Akk
    I want to write a rich domain class such as public class Product { public IEnumerable<Photo> Photos {get; private set;} public void AddPhoto(){...} public void RemovePhoto(){...} } But the entity framework (V4 code first approach) requires an ICollection type for lazy loading! The above code no longer works as designed since clients can bypass the AddPhoto / RemovePhoto method and directly call the add method on ICollection. This is not good. public class Product { public ICollection<Photo> Photos {get; private set;} //Bad public void AddPhoto(){...} public void RemovePhoto(){...} } It's getting really frustrating trying to implement DDD with the EF4. Why did they choose the ICollection for lazy loading? How can i overcome this? Does NHibernate offer me a better DDD experience?

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  • How do you make use of the provider independency in the Entity Framework?

    - by Anders Svensson
    I'm trying to learn more about data access and the Entity Framework. My goal is to have a "provider independent" data access layer (to be able to switch easily e.g. from SQL Server to MySQL or vice versa), and since the EF is supposed to be provider independent it seems like a good way to go. But how do you use this provider independence? I mean, I was expecting to be able to sort of "program to an interface", and then just be able to switch database provider. But as far as I can tell I'm only getting a concrete type to program against, an "Entities" class, e.g. in my case it is: UserDBEntities _context = new UserDBEntities(); What I would have expected to be able to switch provider easily was to have an interface e.g. like IEntities _context = new UserDBEntities(); Sort of like I can do with datasets... But maybe that isn't how it works at all with EF? Or do you just switch provider in the connectionstring, and the model stays the same?? Please remember that I'm a complete newbie at this EF, and rather inexperienced with databases in general, so I would really appreciate if you could be as clear as possible :-)

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  • Trying to edit an entity with data from dropdowns in MVC...

    - by user598352
    Hello! I'm having trouble getting my head around sending multiple models to a view in mvc. My problem is the following. Using EF4 I have a table with attributes organised by category. Couldn't post an image :-( [Have a table called attributes (AttributeTitle, AttributeName, CategoryID) connected to a table called Category (CategoryTitle).] What I want to do is be able to edit an attribute entity and have a dropdown of categories to choose from. I tried to make a custom viewmodel public class AttributeViewModel { public AttributeViewModel() { } public Attribute Attribute { get; set; } public IQueryable<Category> AllCategories { get; set; } } But it just ended up being a mess. <div class="editor-field"> <%: Html.DropDownList("Category", new SelectList((IEnumerable)Model.AllCategories, "CategoryID", "CategoryName")) %> </div> I was getting it back to the controller... [HttpPost] public ActionResult Edit(int AttributeID, FormCollection formcollection) { var _attribute = ProfileDB.GetAttribute(AttributeID); int _selcategory = Convert.ToInt32(formcollection["Category"]); _attribute.CategoryID = (int)_selcategory; try { UpdateModel(_attribute); (<---Error here) ProfileDB.SaveChanges(); return RedirectToAction("Index"); } catch (Exception e) { return View(_attribute); } } I've debugged the code and my _attribute looks correct and _attribute.CategoryID = (int)_selcategory updates the model, but then I get the error. Somewhere here I thought that there should be a cleaner way to do this, and that if I could only send two models to the view instead of having to make a custom viewmodel. To sum it up: I want to edit my attribute and have a dropdown of all of the available categories. Any help much appreciated!

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