CRM 2011-检索关联的[N：N]个实体（C＃）

Question

I'm writing a simple application that imports entities to CRM. Durring this import I need to associate imported entities (custom entity) to another (also custom) entities.

There's no problem with new objects, but when I try to update, I need to delete all associations regarding imported entity and recreated them based on imported data.

How can I do this?

I was thinking of getting all associated entities, and then call disassociate for each of them, but I got stuck trying to get those associated entities.

How should I approach this?

Answer 1

Suppose that you have Student Entity And you want to copy the student Cources to another custom Entity as you said named CStudent
You can use the following code:

var scs = Context.new_Student_CourcesSet.Where(x => x.new_courceid == Cource.Id).ToList<new_Student_Cources>();

var removedsc = Context.new_new_CStudent_CourcesSet.Where(x => x.new_cstudentid == CStudent.Id).ToList<new_CStudent_Cources>();

EntityReferenceCollection relatedEntities = new EntityReferenceCollection();
EntityReferenceCollection removedrelatedEntities = new EntityReferenceCollection();
Relationship relationship = new Relationship(new_CStudent_Cources.EntityLogicalName);

if (removedsc != null)
{
    foreach (new_CStudent_Cources c in removedsc )
    {
        RemovedrelatedEntities.Add(new EntityReference(new_Cources.EntityLogicalName, (Guid)ar.new_courcesid));
    }

    Service.Disassociate(CStudent.LogicalName, CStudnetid, relationship, RemovedrelatedEntities);
}

foreach (new_Student_Cources d in scs)
{
    relatedEntities.Add(new EntityReference(new_Cources.EntityLogicalName, (Guid)d.new_courceid));
}

Service.Associate(CStudent.LogicalName, CStudentid, relationship, relatedEntities);