How to delete all datastore in Google App Engine?

Question

Does anyone know how to delete all datastore in Google App Engine?

Answer 1

This is what you're looking for...

db.delete(Entry.all(keys_only=True))

Running a keys-only query is much faster than a full fetch, and your quota will take a smaller hit because keys-only queries are considered small ops.

Here's a link to an answer from Nick Johnson describing it further.

Below is an end-to-end REST API solution to truncating a table...

I setup a REST API to handle database transactions where routes are directly mapped through to the proper model/action. This can be called by entering the right url (example.com/inventory/truncate) and logging in.

Here's the route:

Route('/inventory/truncate', DataHandler, defaults={'_model':'Inventory', '_action':'truncate'})

Here's the handler:

class DataHandler(webapp2.RequestHandler):
  @basic_auth
  def delete(self, **defaults):
    model = defaults.get('_model')
    action = defaults.get('_action')
    module = __import__('api.models', fromlist=[model])
    model_instance = getattr(module, model)()
    result = getattr(model_instance, action)()

It starts by loading the model dynamically (ie Inventory found under api.models), then calls the correct method (Inventory.truncate()) as specified in the action parameter.

The @basic_auth is a decorator/wrapper that provides authentication for sensitive operations (ie POST/DELETE). There's also an oAuth decorator available if you're concerned about security.

Finally, the action is called:

def truncate(self):
  db.delete(Inventory.all(keys_only=True))

It looks like magic but it's actually very straightforward. The best part is, delete() can be re-used to handle deleting one-or-many results by adding another action to the model.