MS Dynamics: How to remove all association of the Entity

Question

I have an appointment entity which has an association with contact entity. I am trying to remove all association from this appointment entity without explicitly providing contact_id. Here is my code snippet with create appointment entity and then associate with an existing contact.

Entity activity = new Entity("appointment");
activity["scheduledstart"] = DateTime.Now;
activity["scheduledend"] = DateTime.Now.AddMinutes(30);
activity["subject"] = "Test Meeting";
activity["description"] = "Test Description";
activity["owneridname"] = "test_user";
activity["location"] = "Dallas";

EntityCollection attendees = new EntityCollection();
Entity attendee1 = new Entity("activityparty");
attendee1["addressused"] = "test.test@acmegroup.com";
attendees.Entities.Add(attendee1);
activity["requiredattendees"] = attendees;

Guid id = _service.Create(activity);
Console.WriteLine("id: " + id);

AssociateRequest associateRequest = new AssociateRequest();
associateRequest.Relationship = new Relationship("new_appointment_contact");
associateRequest.Target = new Microsoft.Xrm.Sdk.EntityReference("appointment", id);

EntityReferenceCollection referenceCollection = new EntityReferenceCollection();
Microsoft.Xrm.Sdk.EntityReference entityReference = new Microsoft.Xrm.Sdk.EntityReference("contact", new Guid("e6e71e53-b44b-e211-a81e-0050568b36bf"));
referenceCollection.Add(entityReference);
associateRequest.RelatedEntities = referenceCollection;

// Execute the request.
_service.Execute(associateRequest);

I am aware of using DisassociateRequest to remove this association but I don't want to explicitly provide contact_id. I just need something like .Clear() which can remove all contact association.

DisassociateRequest disassociateRequest = new DisassociateRequest();
disassociateRequest.Relationship = new Relationship("new_appointment_contact");
disassociateRequest.Target = new Microsoft.Xrm.Sdk.EntityReference("appointment", id);

EntityReferenceCollection referenceCollection2 = new EntityReferenceCollection();
Microsoft.Xrm.Sdk.EntityReference entityReference2 = new Microsoft.Xrm.Sdk.EntityReference("contact", new Guid("e6e71e53-b44b-e211-a81e-0050568b36bf"));
referenceCollection2.Add(entityReference2);
disassociateRequest.RelatedEntities = referenceCollection2;

// Execute the request.
_service.Execute(disassociateRequest);

Answer 1

I used GetRelatedEntities method to pull all related entities into collection and then use this collection to disassociate all related entities:

DisassociateRequest disassociateRequest = new DisassociateRequest();
disassociateRequest.Relationship = new Relationship("new_appointment_contact");
disassociateRequest.Target = new Microsoft.Xrm.Sdk.EntityReference("appointment", id);

EntityReferenceCollection referenceCollection2 = new EntityReferenceCollection();
Entity existingAppointment = _service.Retrieve("appointment", id, new ColumnSet(true));
foreach (Entity item in existingAppointment.GetRelatedEntities(orgContext, "new_appointment_contact"))
{
    Guid contactId = new Guid(item["contactid"].ToString());
    Microsoft.Xrm.Sdk.EntityReference entityReference2 = new Microsoft.Xrm.Sdk.EntityReference("contact", contactId);
    referenceCollection2.Add(entityReference2);
}
disassociateRequest.RelatedEntities = referenceCollection2;

_service.Execute(disassociateRequest);