ADO.NET Entity Framework and Identity Columns

Question

Is the Entity Framework an identity column?

I am using SQL Server 2005 Express Edition and have several tables where the primary key is the identity column. when I use these tables to create an entity model and use the model in conjunction with the entity with a datasource relationship to the form to create a new object, I am prompted to enter a value for the identity column. Is there a way to make the structure not request values ​​for identity columns?

Answer 1

I know this post is pretty old, but it can help the next person who comes through a Google search for the "Entitiy Framework" and "Identity".

Entity Frameworks seems to respect the primary keys created by the server, as it would if the Identity property were set. However, the application side model still requires that the primary key be supplied in the CreateYourEntityHere method. The key specified here is discarded when the SaveChanges() call is invoked.

The page here contains detailed information about this.

Answer 2

If you are using Entity Framework 5, you can use the following attribute.

 [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 

Answer 3

You must set the identity column identification specification so that the (Ident Identity) property is set to true. You can do this in your table designer in SSMS. You may then need to update the entity data model.

Perhaps this is what you mean by the word "Primary Key - Identification Column", or perhaps you skipped this step.

Answer 4

This is the best answer I've seen. You must manually edit the storage xml layer to set StoreGeneratedPattern="Identity" for each primary key of type UniqueIdentifier , which is set to NewID() by default.

http://web.archive.org/web/20130728225149/http://leedumond.com/blog/using-a-guid-as-an-entitykey-in-entity-framework-4/

Answer 5

Entity Framework knows and can handle identity columns.

Your problem may not be the EF itself, but the generated form. Try removing the entry for the identity column from the insert form and see what happens.

Answer 6

If all else fails before you rip out your hair - try removing the EntityModel and re-importing it from SQL Server. If you set up the keys and relationships and relied on the "update model from the database" function, it is still a bit erroneous in the RC version I found - fresh import may help.

Answer 7

In C #, you can do something like this to find out:

In FooConfiguration.cs : EntityTypeConfiguration<Foo> :

 this.Property(x => x.foo).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); 

Then, to use it, just be sure to insert the element into the context and call context.SaveChanges() before using x.foo to get the updated value with automatic addition. Otherwise, x.foo will be just 0 or null.

Answer 8

Entity structure for some reason does not fully understand Identities. The correct workaround is to set the Setter for this column to Private. This will make any generated user interface understand that it should not set the identifier value, since it is not possible to set a private field for it.

Answer 9

What worked for me is to set StoreGeneratedPattern to None when it is an Identity column. Now everything works in sequence. The main problem is that editing models is extremely difficult if you have many models.

Answer 10

I can not believe this. Intellisensing ItemCollection gives a single item with id = 0 after SaveChanges.

  Dim ItemCollection = From d In action.Parameter Select New STOCK_TYPE With { .Code = d.ParamValue.<Code>.Value, .GeneralUseID = d.ParamValue.<GeneralUse>.Value, } GtexCtx.STOCK_TYPE.AddObject( ItemCollection.FirstOrDefault) GtexCtx.SaveChanges() 

No matter what I do. After 8 hours, including deleting my model, building and rebuilding 35 times, experimenting and editing XML EDMX, it is now almost ready to delete my entire SQL Server database. On the 36th comp, this crazy solution worked

  Dim abc = ItemCollection.FirstOrDefault GtexCtx.STOCK_TYPE.AddObject(abc) GtexCtx.SaveChanges() 

abc.ID yield 41 (identity required)

EDIT: Here is a simple code to think through AddObject and still get the id

 Dim listOfST As List(Of STOCK_TYPE) = ItemCollection.ToList() For Each q As STOCK_TYPE In listOfST GtexCtx.STOCK_TYPE.AddObject(q) Next GtexCtx.SaveChanges() ...more code for inter-relationship tables 

Try entering Intellisence listOfST after SaveChanges and you will find the updated identifier. Maybe there’s a better way, but the concept is there