Relation saved again when update object

General
1

Hi guys,

I have an object “Photo” with a relation of “Comment” objects.
When I write the first comment “Hello, this is first comment” for an existing photo, all goes well and a Photo is updated with a new comment and a new “Comment” is created.

When I write another comment “And this is second comment” for the same photo, I find 3 comments in my “Comment” table. The first comment is duplicate so I have:

1- Hello, this is first comment
2- Hello, this is first comment
3- And this is second comment

And so on…

What I am doing wrong?
The code is:
// Create a new comment object and add it to the photo relation

Comment *comment = [[Comment alloc]init];

[comment setText:text];

[comment setUsername:name];

[photo addComment:comment];

// This is the code for “addComment”

  • (void)addComment:(Comment *)comment {

    if (!self.comments) {

      self.comments = [NSMutableArray array];

    }

    [self.comments addObject:comment];

}

// This is the code to save object photo (and comment too)

[[backendless.persistenceService of:[Photo class]] save:photo];

2

Hi Francesco,

When you save your photo with a comment, the comment will be updated with objectId assigned to it. When you re-save the photo with a collection of comments, the backend will check if the comment object has objectId value. If it does, the backend performs update, otherwise a new one is created.

Check the response for the save operation. It should include the comments with objectId assigned to them.

Regards,
Mark

3

Ok, you’re right and I was forgetting this step.
But what about a user who writes a comment and then adds a new comment just a second later? This is a possible scenario…

4

That’s not a problem. You can always save the comment object directly in the Comment table. Once you know it’s objectID, you can add that object to the photo and save the photo.

5

You are right. The only thing is that I have to complete the entire process in two steps but it’s not a really problem :slight_smile:
I will try…

6

Alternatively, you could have an internal flag that a save operation (for the photo) is in progress. In that case, you’d wait till it comes back before you save the next comment.

7

I used your first approach and it works.

Thank you and sorry for the (maybe) dumb question