1
[Column(Name = "id", IsPrimaryKey = true, CanBeNull = false)] 
public string id { get; set; }

Error:

Cannot insert the value Null into column id, column does not allow nulls

If I set it to an identity column and make a few changes in my [Column attributes] I end up with a IDENTITY insert not enabled error, what should I do? Do I need my primary key column to be an identity as well?

It's just a simple table with +1 increment on primary key 

public partial class linqtest : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            MyContext db = new MyContext("Server=(local);Database=Test;User ID=admin;Password=pw");
            Child c = new Child();
            c.name = "joe "+DateTime.Now;
            db.parents.InsertOnSubmit(c);
            db.SubmitChanges();
        }
    }

    public class MyContext : DataContext
    {
        public static DataContext db;
        public MyContext(string connection) : base(connection) { }
        public Table<Parent> parents;
    }

    [Table(Name="parents")]
    [InheritanceMapping(Code = "retarded", Type = typeof(Child), IsDefault=true)]
    public class Parent
    {
        [Column(Name = "id", IsPrimaryKey = true, CanBeNull = false, DbType = "Int NOT NULL IDENTITY", IsDbGenerated = true)] /* I want this to be inherited by subclasses */
        public int id { get; set; }

        [Column(Name = "name", IsDiscriminator = true)] /* I want this to be inherited by subclasses */
        public string name { get; set; }
    }

    public class Child : Parent
    {

    }
williamsandonz
  • 15,864
  • 23
  • 100
  • 186
  • 1
    why are you setting the primary key?I mean doesn't whatever you are using for your database provide you primary keys? – Bastardo Apr 12 '11 at 20:58
  • do i not have to set isPrimaryKey? thought i did – williamsandonz Apr 12 '11 at 23:40
  • well, if you have a database and some tables in it and using let's say Sql Server or Oracle etc. you dont have to. You can set this up in these programs and they provide primary keys in your table. – Bastardo Apr 13 '11 at 03:48

1 Answers1

1

If I just define my ID column as IsPrimaryKey = true and IsDbGenerated = true, everything works just fine:

[ColumnAttribute(Storage="_ID", AutoSync=AutoSync.OnInsert, 
 DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
public int ID
{....}

Then, in code - when I create a new entity, I just assign the entity an arbitrary ID - I typically tend to use negative numbers:

MyEntity entity = new MyEntity { ID = -55 };

MyContext.MyEntities.InsertOnSubmit(entity);
MyContext.CommitChanges();

After the call to .CommitChanges(), the new entities are stored in the database table, and the actual, real ID values (INT IDENTITY) are being set and reflected on my entity object - i.e. after the call, I get back the real ID that the database has given my new entity.

So my question is: where is your problem then?? It seems to work just fine....

marc_s
  • 732,580
  • 175
  • 1,330
  • 1,459
  • hey! thanks for the reply its working for me now :-) must have been the wording in one of the attributes, the parent is now being added to the DB but the child is not? am i missing something? I've added my full code to the top :) – williamsandonz Apr 12 '11 at 23:16
  • Why the use of negative numbers? –  Feb 21 '12 at 21:43
  • @pst: why not?? The basic idea is this: most users will pick positive ID numbers - most `IDENTITY` specifications start at 1 and increment up. So using negative IDs for temporary entities (that haven't been saved yet) is pretty safe not to cause any collisions with real data that might already be in your table.... – marc_s Feb 21 '12 at 21:46