PostCreate/UpdatePlugin

Here, when a custom entity is created or updated, I am updating a varchar field in the related contact entity

public void Execute(IPluginExecutionContext context)
        {
            DynamicEntity entity=null;

            //Check if the input parameters contains a target of type Dynamic Entity
            if (context.InputParameters.Properties.Contains("Target") &&
                context.InputParameters.Properties["Target"] is DynamicEntity)
            {
                //obtain the entity from the input parameters
                entity = (DynamicEntity)context.InputParameters.Properties["Target"];

                //TextWriter log1 = TextWriter.Synchronized(File.AppendText(@"D:\Srihari Backup\Log.txt"));
                if (entity.Name == "new_testEntity")
                {
                    
                    try
                    {
                        //log1.WriteLine("inside try");                       

                        
                        DynamicEntity testEntity= (DynamicEntity)context.InputParameters[ParameterName.Target];
                        string clinicName = String.Empty;
                        string contactId= String.Empty;

                        if (testEntity.Properties.Contains("new_clinicname"))
                        {
                            clinicName = (string)testEntity["new_clinicname"];
                            //log1.WriteLine(clinicName);
                        }
                        if (context.MessageName == MessageName.Create)
                        {
                            if (testEntity.Properties.Contains("new_contactid"))
                            {
                                //log1.WriteLine("contains patient id");                                

              //Since the contact is a lookup, cast the object as a lookup.
                                //log1.WriteLine("create message :-");
                                Lookup contactLookup = (Lookup)testEntity["new_contactid"];
                                contactLookup.type = EntityName.contact.ToString();
                                contactId= contactLookup.Value.ToString(); //get the guid of the lookup   
                            }                   
                           
                            
                        }
                        else if (context.MessageName == MessageName.Update)
                        {
                            //log1.WriteLine("update message :-");
//Since this is an update, only the values updated on the form will be available in the context. Hence I am getting the value from an Image that I have registered.
                            DynamicEntity postTestEntity = (DynamicEntity)context.PostEntityImages["contactId"];//The name or 'entityalias' of the image
                            //log1.WriteLine(postCCProvider);
                            Lookup contactLookup = (Lookup)postTestEntity.Properties["new_contactid"];
                            //log1.WriteLine(patientLookup);
                            contactId = contactLookup.Value.ToString();
                            //log1.WriteLine(patientId);

                            //log1.Close();
                        }
                        
                        DynamicEntity contact = new DynamicEntity();
                        contact.Name = EntityName.contact.ToString();

                        Key contactKey = new Key();
                        contactKey.Value = new Guid(contactId);

                        KeyProperty contactGuid = new KeyProperty();
                        contactGuid.Name = "contactid";                 
                        contactGuid.Value = contactKey;
                        contact.Properties.Add(contactGuid);

                        //set the field that needs to be updated in the contact entity.
                        StringProperty ccProviderNameProperty = new StringProperty("new_communitycareprovider", clinicName);
                        contact.Properties.Add(ccProviderNameProperty);

                        ICrmService service = context.CreateCrmService(true);
                        service.Update(contact);


                        
                    }
                    catch (SoapException soapEx)
                    {
                        //log1.Close();
                        throw new InvalidPluginExecutionException("Soap error occured in the plugin", soapEx);                        
                        
                    }
                    catch (Exception ex)
                    {
                        //log1.WriteLine(ex.Message);
                        //log1.Close();
                        throw new InvalidPluginExecutionException("An error occured in the plugin", ex);
                    }
                }
            }
            else
            {
                return; 
            }

           
        }