Entity Framework Extensions MergeKeepIdentity

Description

The BulkOperation.InsertKeepIdentity sets if the source identity value should be preserved on Merge. When not specified, identity values are assigned by the destination.

In the following example, the MergeKeepIdentity is enabled and the specified value for IdentityInt column will be stored in the database instead of the database generated values on MERGE operation.

using (var context = new EntityContext())
{
    var list = context.Customers.ToList();
    list.ForEach(x => x.Name += "_Merged" );
    list.ForEach(x => x.IdentityInt += 100 );
    list.Add( new Customer() { CustomerID = 3, IdentityInt = 4, Name ="Customer_C" });

    context.BulkMerge(list, options => options.MergeKeepIdentity = true);
}

Try it: EF Core | EF6

• The IdentityInt column for existing records will not be updated, only for the new records, it will preserve the specified value.

Purpose

The MergeKeepIdentity option lets you keep the source identity value when merging.

By example, when importing a file, you may want to keep the specified value.