Entity Framework Error: EntityKey object with null value cannot be bound to context object

Question

In my application, I have the following code ...

public Boolean SaveUserInformation(UserInfoDTO UserInformation) { return dataManager.SaveUserInfo(new UserInfo() { UserInfoID = UserInformation.UserInfoID.HasValue ? UserInformation.UserInfoID.Value : 0, UserID = UserInformation.UserID, ProxyUsername = UserInformation.ProxyUsername, Email = UserInformation.Email, Status = UserInformation.Status }); } 

This code calls the method in the dataManager object, which uses the Entity Framework ...

  public Boolean SaveUserInfo(UserInfo userInfo) { try { //Validate data prior to database update if (userInfo.UserID == null) { throw new Exception("UserInfoDomainModel object passed to PriorityOne.Data.DataManager.SaveUserInfo with UserID property set to NULL."); } if (userInfo.ProxyUsername == null) { throw new Exception("UserInfoDomainModel object passed to PriorityOne.Data.DataManager.SaveUserInfo with ProxyUsername property set to NULL."); } if (userInfo.Email == null) { throw new Exception("UserInfoDomainModel object passed to PriorityOne.Data.DataManager.SaveUserInfo with Email property set to NULL."); } if (userInfo.UserInfoID == 0) { //Perform Insert using (PriorityOneEntities entities = new PriorityOneEntities()) { entities.UserInfoes.AddObject(userInfo); entities.SaveChanges(); } } else { //Perform Update using (PriorityOneEntities entities = new PriorityOneEntities()) { entities.Attach(userInfo); entities.SaveChanges(); } } return true; } catch (Exception ex) { //TODO: Log Error return false; } } 

Inserting this code works just fine. But when I try to update, I get an error: "An object with a null EntityKey cannot be bound to the context of the object."

This happens on this line of code: entities.Attach (userInfo);

What I'm trying to do is to avoid traveling together to the database in order to select the entry that I later make changes and updates, thereby making two round trips to the database.

Any ideas what is going wrong, or how could I do it better?

Thanks.

Answer 1

It looks like you are using EF 4.1+
You must tell EF that you want your entity to be updated (changed state):

 //Perform Update using (PriorityOneEntities entities = new PriorityOneEntities()) { entities.Entry(userInfo).State = EntityState.Modified; entities.SaveChanges(); } 

PS You do not need to explicitly call Attach . This is done under the hood.

Update :
Based on your comments, you are using EF 4.0. Here you need to have your object modified in EF 4.0:

  ctx.AddObject("userInfoes", userInfo); ctx.ObjectStateManager.ChangeObjectState(userInfo, EntityState.Modified); ctx.SaveChanges(); 

You cannot use the Attach method. From http://msdn.microsoft.com/en-us/library/bb896271.aspx :

If more than one object of a certain type has the same key value, the Entity Framework will throw an exception. To avoid getting an exception, use the AddObject method to attach individual objects and then change the state accordingly.

Answer 2

From MSDN

The object passed to the Attach method must have a valid EntityKey value. If the object does not have a valid EntityKey value, use the AttachTo method to specify the name of the set of objects.

Hope this helps you.