Tip 16 – How to mimic .NET 4.0’s ObjectSet today

re: Tip 16 – How to mimic .NET 4.0’s ObjectSet today

Alex D James — Sat, 20 Jun 2009 20:58:31 GMT

Martin,

That is pretty cool. And works well with EntityObject. Bear in mind though that your cool solution won't work if you convert to POCO classes in .NET 4.0

Did you look at the other implementation of GetEntitySet name that I wrote? The one I did in Tip13. That is more general purpose, and will work in POCO classes too.

Alex

re: Tip 16 – How to mimic .NET 4.0’s ObjectSet today

Martin Robins — Sat, 20 Jun 2009 12:55:55 GMT

As an alternative to selecting the entity set name from the query, I created the following extension method based upon the thread at http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/3fc700f6-30de-4346-b1ed-09df8c21c273 ...

public static string GetEntitySetName<T>(this ObjectContext ctx) where T : EntityObject {

EdmEntityTypeAttribute attribute = ((EdmEntityTypeAttribute[])typeof(T).GetCustomAttributes(typeof(EdmEntityTypeAttribute), true)).Single();

EntityContainer container = ctx.MetadataWorkspace.GetEntityContainer(ctx.DefaultContainerName, DataSpace.CSpace);

return container.BaseEntitySets.Single(es => es.ElementType.Name == attribute.Name).Name;

}

this allows the entity set to be determined based upon the attributes in the model and can be used as follows...

public static void AddObject<T>(this ObjectQuery<T> query, T entity) where T : EntityObject {

query.Context.AddObject(query.Context.GetEntitySetName<T>(), entity);

}

public static void Attach<T>(this ObjectQuery<T> query, T entity) where T : EntityObject {

query.Context.AttachTo(query.Context.GetEntitySetName<T>(), entity);

}

re: Tip 16 – How to mimic .NET 4.0’s ObjectSet today

Martin Robins — Sat, 20 Jun 2009 12:49:03 GMT

public static string GetEntitySetName<T>(this ObjectContext ctx) where T : EntityObject {

EdmEntityTypeAttribute attribute = ((EdmEntityTypeAttribute[])typeof(T).GetCustomAttributes(typeof(EdmEntityTypeAttribute), true)).Single();

EntityContainer container = ctx.MetadataWorkspace.GetEntityContainer(ctx.DefaultContainerName, DataSpace.CSpace);

return container.BaseEntitySets.Single(es => es.ElementType.Name == attribute.Name).Name;

}

Tip 26 – How to avoid database queries using Stub Entities

VS2010学习 — Sat, 20 Jun 2009 05:35:54 GMT

What are Stub Entities? A stub entity is a partially populated entity that stands in for the real thing

Tip 26 – How to avoid database queries using Stub Entities

Meta-Me — Fri, 19 Jun 2009 21:00:39 GMT

What are Stub Entities? A stub entity is a partially populated entity that stands in for the real thing.

re: Tip 16 – How to mimic .NET 4.0’s ObjectSet today

Alex D James — Mon, 04 May 2009 20:24:23 GMT

@dsoltesz

Absolutely you are right, for add operations, but the point is this is much easier for other operations like Attach(), and it costs very little to extend it to support Add too.

Also I actually prefer the intellisense experience typing

ctx.Customers.Add(...

as opposed to

ctx.AddToCustomer(...

where I have to look through all the AddToX(...) methods to get the one I'm after.

Its a little thing I know but it does make a difference.

Alex

re: Tip 16 – How to mimic .NET 4.0’s ObjectSet today

dsoltesz — Mon, 04 May 2009 17:29:57 GMT

Even with 3.5 sp1 you don't have to use the

ctx.AddObject(“Customers”, newCustomer);

you can simply say ctx.AddToCustomers(newCustomer);

Tip 16 – How to mimic .NET 4.0’s ObjectSet today - Alex James

DotNetShoutout — Sat, 02 May 2009 00:41:59 GMT

Thank you for submitting this cool story - Trackback from DotNetShoutout

Meta-Me : Entity Framework Tips

Meta-Me : Entity Framework Tips — Fri, 01 May 2009 19:42:42 GMT

PingBack from http://blogs.msdn.com/alexj/archive/2009/03/26/index-of-tips.aspx