Define field as auto increment in EF5 migration

Question

I am creating a table using EF migration, for example:

this.CreateTable("Message", c => new { Id = c.Long(nullable: false, identity: true, defaultValue: 0), Subject = c.String(nullable: false, maxLength: 64), Body = c.String(nullable: false, isMaxLength: true) }) .PrimaryKey(c => c.Id) .Index(c => c.Id, unique: true); 

How to define an id field for auto_increment? I'm sure it should be possible, but I'm just trying to figure out ...

Thanks.

Answer 1

Well, it seems that setting the "identity: true" property in the field should be enough, but for some reason the field is not defined as IDENTITY (1, 1).

A workaround was found in this post:

http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/33db16ac-e166-455f-a47b-1e5fe0557979/

And it worked for me like this:

 Id = new ColumnModel(PrimitiveTypeKind.Int64) { IsNullable = false, IsIdentity = true }, 

Now its defining the column as IDENTITY (1, 1)

Answer 2

If you want to automatically generate it in the code, you can skip the annotation in the "Identifier" field and do something like below.

 public abstract class AbstractContext : DbContext { /// <summary> /// Custom processing when saving entities in changetracker /// </summary> /// <returns></returns> public override int SaveChanges() { // recommended to explicitly set New Guid for appropriate entities foreach (var entry in ChangeTracker.Entries<ModelBase>().Where(e => e.State == EntityState.Added) ) { // only generate if property isn't identity... Type t = entry.Entity.GetType(); var info = t.GetProperty("Id").GetCustomAttributes( typeof(DatabaseGeneratedAttribute), true).Cast<DatabaseGeneratedAttribute>().Single(); if (info.DatabaseGeneratedOption != DatabaseGeneratedOption.Identity) { entry.Entity.Id = Guid.NewGuid(); // now we make it } } return base.SaveChanges(); } } 

For more information, check Entity Key Management.

I got this from the link I showed above the comment.

Hope this helps you.