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Once again, Parse disappointed me with their developer support.

Their Anonymous User feature is a great feature, but it lacks the last 10% to be awesome.

When I was using the feature and did a query, it crashed.

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Tried to save an object with a new, unsaved child.'

I found the same incident on Parse forum.

The reply from a Parse official rep is again disappointing.

Let me explain the pitfalls and shortcoming of Parse:

• Parse will automatically save an Anonymous User when an a PFUser (as an object or as a relation) is saved

• However, calling PFQuery, it will trigger the error because no object was automatically saved (probably due to your logic flow)

• Yet, strangely it seems, a PFQuery does not handle an anonymous user situation at all, and caused the crash

I felt this is a bug, just like the 2 other developers in the forum. Unfortunately, the forum, yet again, is closed for comments.

Parse, please improve your library.

Workaround

As suggested, one could check to make certain PFUser is saved by checking the objectId. If it isn’t, save it, then perform the query:

if ([PFUser currentUser].objectId == nil)
  [[PFUser currentUser] saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
    // Perform the query fetch in block
  }];
else
  // Perform the query fetch directly