Q:

initialize GAE datastore with start data?

this is my first question on stackoverflow and I'm new to programming:
What is the right way to load data into the GAE datastore when deploying my app? This should only happen once at deployment.
In other words: How can I call methods in my code, such that these methods are only called when I deploy my app?
The GAE documentation for python2.7 says, that one shouldn't call a main function, so I can't do this:
if __name__ == '__main__':
   initialize_datastore()
   main()

A:

Create a handler that is restricted to admins only. When that handler is invoked with a simple GET request you could have it check to see if the seed data exists and if it doesn't, insert it. 
Configuring a handler to require login or administrator status.
Another option is to write a Python script that utilizes the Remote API. This would allow you to access local data sources such as a CSV file or a locally hosted database and wouldn't require you to create a potentially unwieldy handler.
Read about the Remote API in the docs.
Using the Remote API Shell  - Google App Engine

