CRM 2011 LINQ – Entity Instance Tracking

An interesting query came up in the CRM Development Forum on MSDN recently:

http://social.msdn.microsoft.com/Forums/en-US/crmdevelopment/thread/83d49d47-1fc0-4181-99c6-229b658c99f3

which I will repeat here for context:

I currently have a plugin that triggers anytime a user creates, updates, or deletes a record out of a custom entity named Conflict of Interest. The plugin will update a flag on the contact record that lets a user know if there is an active conflict of interest. When I try to run the linq update I get an error “The context is not currently tracking the ‘contact’ entity“.

This sets up the IOrganizationService:

IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);

// This function creates the linq query to update the contact record
public void SetActor_ConflictOfInterest(IOrganizationService service, Guid ActorGUID)
    {
      Utilities util = new Utilities();
      Guid BillingHeader = Guid.Empty;
      var xrm = new XrmServiceContext(service);

      var Actor = new Xrm.Contact
      {
        ContactId = ActorGUID,
        new_ConflictofInterest = true,
      };
      xrm.UpdateObject(Actor);
      xrm.SaveChanges();
    }

I’ve tried updating the record with a sql query as well, but CRM is locking the contact record for some reason. Any ideas on the linq error and why CRM is locking the contact record?

I’d never seen the error before, so I set off to see if I could replicate it.  It was not difficult:

var xrm = new Xrm2011.XrmServiceContext("Xrm");

Guid ActorGUID = (from c in xrm.ContactSet where c.FullName == "aa test 2" select c.Id).FirstOrDefault();

xrm.ClearChanges();

Xrm2011.Contact Actor = new Xrm2011.Contact
{
	Id = ActorGUID,
	DoNotEMail = true
};

xrm.UpdateObject(Actor);
xrm.SaveChanges();</pre>
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<pre>

And bingo!!  As soon as I execute the .UpdateObject() method, I receive the error:

The context is not currently tracking the ‘contact’ entity.

According to my  reading through the SDK, we’re being told that the XRM LINQ Context is not currently keeping track of the changes in our ‘contact’ entity instance (identified by the GUID that we have assigned to our new Xrm2011.Contact object).

Ordinarily when interacting with the CRM via the XRM context, we follow a pattern:

1. Retrieve entity instance(s)
2. Update entity instance(s)
3. Save

OrganizationServiceContext.Attach()

But in this case we’re trying to update an entity instance by creating its representation from scratch; so the context knows nothing about it.  The solution is the context.Attach() method:

Guid ActorGUID = (from c in xrm.ContactSet where c.FullName == "aa test 2" select c.Id).FirstOrDefault();

Xrm2011.Contact Actor = new Xrm2011.Contact
{
	Id = ActorGUID,
	DoNotEMail = true
};

xrm.Attach(Actor);
xrm.UpdateObject(Actor);
xrm.SaveChanges();

which attaches our ‘contact’ entity instance to the context, so that it can track the changes.  So we run the code and we’re greeted with this:

The context is already tracking a different ‘contact’ entity with the same identity.

What’s going on?  First, we’re not tracking the ‘contact’ and now we are?  But not?

What happens is this:

1. Our initial LINQ query retrieves the GUID identifier for the ‘contact’ entity instance we’re interested in.  This tracks the ‘contact’ in context so that the context can keep up to date with any changes.  However, because we are only extracting the GUID, we’re throwing away our reference to the ‘contact’ entity instance that it being tracked.
2. We construct our ‘contact’ entity instance and set whichever attributes are of relevance.
3. We attempt to attach our ‘contact’ entity instance to the context.  However, this entity refers to the same entity instance (that is, identified by the same GUID) that was already added to context by our query in (1).  Hence, the error.

So, what do we do now?

There are two solutions in this case:

1. Keep hold of the original entity instance reference; return the instance and not just the GUID.
2. Remove the original entity instance reference from context.  We can do this with either the .Detach() method or .ClearChanges() method.

OrganizationServiceContext.Detach()

This method will remove an entity instance from the context and stop tracking changes.  To use this method, you must have a reference to the entity instance.  So this would require a combination of options (1) and (2) above:

1. Hold onto the original entity instance reference
2. .Detach() it
3. Create your new entity instance reference and .Attach()
4. Update
5. Save

OrganizationServiceContext.ClearChanges()

This method will remove ALL entity instances from context and stop tracking changes for ALL entity instances.  This will allow us to .Attach and .Update without holding onto the original entity instance:

Guid ActorGUID = (from c in xrm.ContactSet where c.FullName == "aa test 2" select c.Id).FirstOrDefault();

xrm.ClearChanges();

Xrm2011.Contact Actor = new Xrm2011.Contact
{
	Id = ActorGUID,
	DoNotEMail = true
};

xrm.Attach(Actor);
xrm.UpdateObject(Actor);
xrm.SaveChanges();

Conclusion

Which combination of tracking methods you use in your application will depend entirely upon what you need to accomplish, but armed with this knowledge at least you’ll know which tools you have at your disposal.