c# - EntityFramwork 6 - ID not set when calling SaveChanges() -

i got little problem entityframework. setup follows : using code-first migrations , database structure :

using microsoft.azure.mobile.server;  namespace myproject.dataobjects {     public class listrelations : entitydata     {         public string userid { get; set; }         public bool read { get; set; }         public bool write { get; set; }     } } 

now inherting enititydata should add id field , meta data stuff, right ? when try populate database :

            var relations = new listrelations();             relations.userid = currentuser;             relations.read = true;             relations.write = true;             relations.listid = current.id;             context.listrelationsset.add(relations);             try {                 context.savechanges();             }             catch (dbentityvalidationexception dbex)             {                 foreach (var validationerrors in dbex.entityvalidationerrors)                 {                     foreach (var validationerror in validationerrors.validationerrors)                     {                         trace.traceinformation("property: {0} error: {1}",                                                 validationerror.propertyname,                                                 validationerror.errormessage);                     }                 }             } 

i getting errors, saying id field needed populated. but, shouldnt database me ? bit confused, welcoming help!

use

public class listrelations : entitydata {     [databasegenerated(databasegeneratedoption.identity),      column(typename = "varchar"),      maxlength(20),      key]     public string userid { get; set; }     public bool read { get; set; }     public bool write { get; set; } } 

it depends on database provider, instance t-sql has procedure called newsequentialid() populate these kind of columns.

sample use in migration be

 id = c.guid(nullable: false, identity: true, defaultvaluesql: "newsequentialid()"),