Custom Workflow activity to Associate records

gistfile1.txt

using Microsoft.Xrm.Sdk;
using Microsoft.Xrm.Sdk.Workflow;
using System;
using System.Activities;
using Microsoft.Xrm.Sdk.Query;

namespace CRMWorkflowProject1
{
    public class AssociateOpportunityMembers : CodeActivity
    {       
        // Input parameter für Requests an datahub definieren
        [RequiredArgument]
        [Input("Hauptbetreuer")]
        [ReferenceTarget("tt_mitarbeiter")]
        public InArgument<EntityReference> Hauptbetreuer { get; set; }

        
        protected override void Execute(CodeActivityContext executionContext)
        {
            ITracingService tracer = executionContext.GetExtension<ITracingService>();
            IWorkflowContext context = executionContext.GetExtension<IWorkflowContext>();
            IOrganizationServiceFactory serviceFactory = executionContext.GetExtension<IOrganizationServiceFactory>();
            IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);

            try
            {
                // Create a new entity reference for the main account manager including GUID and name
                EntityReference Employee = Hauptbetreuer.Get<EntityReference>(executionContext);
                Entity EmployeeName = service.Retrieve("tt_mitarbeiter", Employee.Id, new ColumnSet("tt_name"));
                Employee.Name = EmployeeName.GetAttributeValue<string>("tt_name");
                
                
                // Check if account manager has already been associated
                ConditionExpression condition1 = new ConditionExpression();
                condition1.AttributeName = "opportunityid";
                condition1.Operator = ConditionOperator.Equal;
                condition1.Values.Add(context.PrimaryEntityId);

                ConditionExpression condition2 = new ConditionExpression();
                condition2.AttributeName = "tt_mitarbeiterid";
                condition2.Operator = ConditionOperator.Equal;
                condition2.Values.Add(Employee.Id);

                FilterExpression filter1 = new FilterExpression();
                filter1.Conditions.Add(condition1);
                filter1.Conditions.Add(condition2);

                QueryExpression query = new QueryExpression("pb_opportunity_tt_mitarbeiter");
                query.ColumnSet.AddColumns("tt_mitarbeiterid");
                query.Criteria.AddFilter(filter1);

                EntityCollection associates = service.RetrieveMultiple(query);

                // Associate Account Manager to opportunity in case he/she hasn't been added so far
                if (associates.Entities.Count == 0)
                {
                    EntityReferenceCollection relatedEntities = new EntityReferenceCollection();
                    relatedEntities.Add(Employee);

                    Relationship relationship = new Relationship("pb_opportunity_tt_mitarbeiter");

                    service.Associate(context.PrimaryEntityName, context.PrimaryEntityId, relationship, relatedEntities);
                }
            }
            catch (Exception e)
            {
                throw new InvalidPluginExecutionException(e.Message);
            }
        }
    }
}