How do I tell Entity (Code First) to not send the Key ID field to the database?

Question

My code:

Models.Resource r = new Models.Resource();
r.Name = txtName.Text;
r.ResourceType = resTypes.Find(rt => rt.Name == "Content");

r.ResourceContents.Add(_resourceContent.Find(rc => rc.ID == _resourceContentID));

ctx.Resource.Add(r);
ctx.SaveChanges();

ctx.SaveChanges() causes the error: Cannot insert explicit value for identity column in table 'Resources' when IDENTITY_INSERT is set to OFF.

Looking at what's being sent to SQL: ADO.NET:Execute NonQuery "INSERT [dbo].[Resources]([ID], [Name], [Description], [IsOnFile], [ContentOwnerAlias], [ContentOwnerGroup], [ResourceTypes_ID]) VALUES (@0, @1, @2, @3, @4, @5, NULL)"

My POCO Resource has ID as a Key:

public partial class Resource
{
  public Resource()
  {
  }

  [Key]
  public int ID { get; set; }

And my Map code:

public class ResourceMap : EntityTypeConfiguration<Resource>
{
  public ResourceMap()
  {
    // Primary Key
    this.HasKey(t => t.ID);

How do I tell Entity to not send the Key ID field to the database?

Alexandre Rondeau Alexandre Rondeau · Accepted Answer · 2013-12-19T02:41:45

If your PK is generated by the database (like an identity) you have to configure it in your Map.

public class ResourceMap : EntityTypeConfiguration<Resource>
{
   public ResourceMap()
   {
        // Primary Key
        this.HasKey(t => t.ID);
        this.Property(t => t.ID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
   }
}

How do I tell Entity (Code First) to not send the Key ID field to the database?

2 Answers