I am a self taught "developer". I use the term loosely because I only know enough to make myself dangerous. I have no theory background, and I only pick up things to get this little tool to work or make that control do what I want. That said, I am looking for some reading material that explains some of the theory behind application dev...
I have a windows service that runs every 10 seconds ... each time it runs, it takes some test data, modifies it and persists it to the database using the EntityFramework. However, on every second run, when I try to persist the change I get the following Optimistic Concurrency Exception:- Store update, insert, or delete statement affe...
I can set an EntityReference on an entity without having to load the relevent entity as follows: this.CategoryReference.EntityKey = new EntityKey("MyEntities.CategorySet", "Id", 12); So I can set the Category for the entity I'm dealing with to whatever category has id 12 without having to hit the database. But is there a way to do t...
Hello, It appears to me that a strange phenomenon is occurring with inherited entities (TPT) in EF4. I have three entities. 1. Asset 2. Property 3. Activity Property is a derived-type of Asset. Property has many activities (many-to-many) When modeling this in my EDMX, everything seems fine until I try to insert a new Property into th...
Hello, I have a database (sql 2008 mdf file), a class library project with an edmx file, created with the wizard. So the connection string is also made by the wizard. This project is on a teamfoundation server. I can use all the wizard made objects when coding. But when i run the program and I try to make an entityContainerName, the ...
When use entity framework for DAL tier, VS 2010 can create edmx for each database. Question: If I have a database with many tables, should I create only one edmx for all tables or mutiple edmx files? for example, maybe all security tables for one edmx file, other tables for another edmx file. If there is more than one, then in other ti...
One of the features provided by RIA services is that your server-side model objects get automatically proxied in your Silverlight front end and are automatically serialized back to the server for operations such as saving to the database. This seems to be a very similar goal to what "Self Tracking Entities" are providing, which is a tec...
Good day, I am developing using Entity Framework and WPF, and I am encountering some errors and I don't know why. When saving a record (using a BackgroundWorker), I set the entities change tracker to nothing (null), attach the record to a new disposable context, save it, detach, and dispose of the context. Saving a record fires and ev...
Suppose I have an Entity Order with OrderDetails as child preperty. I enable lazyloading like this: _context.ContextOptions.LazyLoadingEnabled = true; I Can feed a view with a method like this: Order.GetAll() And navigate by the order details automatically without getting the wirerd "Object reference not set to an instance of an ...
I'm attempting to implement a repository pattern with my poco objects auto generated from my edmx. In my repository class, I have: IObjectSet<E> _objectSet; private IObjectSet<E> objectSet { get { if (_objectSet == null) { _objectSet = this._context.CreateObjectSet<E>(); } return _obj...
IEnumerable<Department> myQuery = (from D in myContext.Departments orderby D.DeptName select D); var myQuery = (from D in myContext.Departments orderby D.DeptName select D); What is the difference between these two statements above? In my little asp.net/C#/ EF4.0 app I can write them either way, and as far as how I want to use them, t...
Hello guys! I was confused with my problem. I'm using Entity Framework and want to save entities on hard disk and then to restore them. I have no problem with Serializing/Deserializing but i get an exception "The object cannot be added to the ObjectStateManager because it already has an EntityKey. Use ObjectContext.Attach to attach an ob...
We are starting a new project where we need to store product and many product attributes in a database. The technology stack is MS SQL 2008 and Entity Framework 4.0 / LINQ for data access. The products (and Products Table) are pretty straightforward (a SKU, manufacturer, price, etc..). However there are also many attributes to store w...
I got two entities: public class User : Entity { public virtual string Username { get; set; } public virtual string Email { get; set; } public virtual string PasswordHash { get; set; } public virtual List<Photo> Photos { get; set; } } and public class Photo : Entity { public virtual string FileName { get; set; } ...
Hi, I am trying to use an Entity Framework Model (in separate project) into an asp.net 4 MVC project (VS2010, C#) If I create the EF inside the MVC project I have no problems. I think I am missing some step. things done: 1. added reference to the EF class project 2. added connection string in MVC web.config 3. added reference to System...
How to filter nested/child collections of entities when including them in EF? Example: Let's have standard Customer-Orders association. How to load all customers and include only their last three orders in their Orders collection? Is there something like AssociateWith function from L2S for EF? ...
OK, I want to make sure I cover my situation and everything I've tried thoroughly. I'm pretty sure what I need/want can be done, but I haven't quite found the perfect combination for success. I'm utilizing Entity Framework 4 RTM and its POCO support. I'm looking to query for an entity (Config) that contains a many-to-many relationship...
I have a product entity, which has 0 or 1 "BestSeller" entities. For some reason when I say: db.Products.OrderBy(p => p.BestSeller.rating).ToList(); the SQL I get has an "extra" outer join (below). And if I add on a second 0 or 1 relation ship, and order by both, then I get 4 outer joins. It seems like each such entity is producing ...
Hey everyone, I had a couple of questions relating to the .NET Entity Framework and using stored procedures. Here goes: I know that we can right click a stored procedure and choose Function Import to be able to use with code. Is there a way to do this for many stored procedures at once? When doing a Function Import, I can create a ne...
I'm having a look at Entity Framework and everything I'm reading takes a data centric approach to explaining EF. By that I mean that the fundamental relationships of the system are first defined in the database and objects are generated that reflect those relationships. Examples Quickstart (Entity Framework) Using Entity Framework en...