Can't access attributes of a PFRelation - ios

Question

I'm trying to get the name of a Client that is owner of a Vitrine.
Here is my code.
To save the data I'm doing this:
self.vitrine["username"] = PFUser.currentUser()?.username
self.vitrine["name"] = nameTextField.text as String
var relation = self.vitrine.relationForKey("client")
relation.addObject(self.client)
self.vitrine.saveEventually { (success, error) -> Void in
if(error == nil){
}else{
println(error?.userInfo)
}
self.fetchAllVitrines()
self.navigationController?.popToRootViewControllerAnimated(true)
}
}
And it works. In the Parse I can see the relation working.
I'm trying to access data of relation doing this:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCellWithIdentifier("vitrineCell", forIndexPath: indexPath) as! VitrineTableViewCell
var object: PFObject = self.vitrineObjects.objectAtIndex(indexPath.row) as! PFObject
cell.nomeLabel.text = object["name"] as? String
let x: PFRelation = object["client"] as! PFRelation
// cell.clientNameTextView.text = object["client"]["name"] as String
return cell
}
But when I log the data inside client column is that what appear for me:
<PFRelation: 0x7b7f1390, 0x7b7cfdc0.client -> Client>
Please somebody helps me. I'm on that for 2 days. I read more than 3 times the Parse Doc. and I don't find a way to do that.
Regards,
Diogo Amaral
Well, I add the code:
query!.getFirstObjectInBackgroundWithBlock {
(object: PFObject?, error: NSError?) -> Void in
if error != nil || object == nil {
println("The getFirstObject request failed.")
} else {
println(object)
cell.clientNameTextView.text = object["name"] as? String
}
}
But the line: cell.clientNameTextView.text = object["name"] as? String
throws me an error. "Cannot assign a value of type 'String?' to a value of type 'String!'"...
I already tried:
cell.clientNameTextView.text = object["name"] as! String
cell.clientNameTextView.text = object["name"] as String
cell.clientNameTextView.text = object["name"] as? String
How do I can fix that?

Answer 1

If you're using a relation (rather than a pointer) then you need to be aware that relations store arrays of their destination objects. So, when you execute
var relation = self.vitrine.relationForKey("client")
relation.addObject(self.client)
you're adding self.client to the array of clients. If a vitrine can only have a single owner, and this should be stored in the client field, then you probably want to use a Pointer rather than a Relation.
Because of this array, your code as written just won't work. You need get the relation from your vitrine object, query it, extract the element from the array you want, and then you can use it.
let x: PFRelation = object["client"] as! PFRelation
let query = x.query()
// Lets say that you are only interested in the first element in your array...
query.getFirstObjectInBackgroundWithBlock { first, error in
// Should do error checking here
cell.clientNameTextView.text = first!.objectForKey("name") as? String
}
This method is also a bit inefficient. You should use some form of caching, or ideally, determine if you really do need to use a Relation or if a Pointer will suffice. If a Pointer will do, you can also include the data it points to when you run your original query via the includeKey method on PFQuery. You can't use includeKey on a Relation.