title: Adding core data records to Entity based on Relationships
body: <p>I have two entities ProductModel and OrderItem. ProductModel has relationship set prodToOrder, inverse orderToProd and one to Many. OrderItem has relationship set with orderToProd with inverse prodToOrder and Many to one.</p>
  
  <p>I have added ProductModel data with out issues but my problem is after i inserted new records to OrderItem then go back and fetch the OrderItem, the product name is null. If i insert both records to ProductModel and OrderItem at the same time it will work but i do not added both entities as the same time i need to pick already existing product name and add the details to OrderItem.</p>
  
  <p>I think the problem is that unless i insert records to both entities at the same time the relationship will not be created.</p>
  
  <p>I Perform the new OrderItem in the below function:</p>
  
  <pre>
      - (IBAction)cmdSave:(id)sender {
  
  
      //Get max productid
      NSNumber *orderitemid =[self getMaxOrderItemID];
      NSNumber *addValue= [NSNumber numberWithInteger:([orderitemid integerValue] + 1) ];
      NSManagedObjectContext *context = [self managedObjectContext];
  
      // Create a new managed object
      OrderItem *orderDetails = [NSEntityDescription insertNewObjectForEntityForName:@"OrderItem" inManagedObjectContext:context];
      ProductModel *prod  =[NSEntityDescription insertNewObjectForEntityForName:@"ProductModel" inManagedObjectContext:context];
  
  
      orderDetails.order-id=[NSNumber numberWithInteger:[addValue integerValue]];
      orderDetails.product-id =[NSNumber numberWithInteger:[product-id integerValue] ];
      orderDetails.qty = [NSNumber numberWithInteger:[self.txtQty.text integerValue]];
      orderDetails.price =[NSDecimalNumber numberWithDouble:[self.txtPrice.text doubleValue]]; 
      orderDetails.total = [NSDecimalNumber numberWithDouble:[self.txtTotal.text 
         doubleValue]];
  
     //if i do the following statement it will insert product id to ProductModel entity but i do not want to do that and how do i maintain relationships without inserting in to ProductModel.
  
  
  ***   prod.product-id=[NSNumber numberWithInteger:[product-id integerValue] ];
     orderDetails.orderToProd=prod;
    ***
  
      NSError *error = nil;
      // Save the object to persistent store
      if (![context save:&error]) {
          NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]);
      }
     }
  
  </pre>
  
  <p>I appreciate your help or advice on this please.</p>