App Engine: create object inside a transaction -


I am writing a site on GAE-Java + Objectify that makes users create their own pages with unique URLs . I have not understood a clear way to ensure that when two users try to claim the same URL at the same time, then only one user gets it.

This is what I am trying to do.

  • User 1 does a check - Available to
  • User 2 checks - Available to
  • Meanwhile, the user creates 1 page and store it.
  • User 2 creates a page and overrides user 1.

    • Any ideas on how to fix it on GAE?

    Why not just run your code? I do not think where this problem is, do you have a sample of something that you have tried to do and have problems with it?


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