Implementing "Starts with" and "Ends with" queries with Google App Engine

Question

Hi,

Am wondering if anyone can provide some guidance on how I might implement a starts with or ends with query against a Datastore model using Python?

In pseudo code, it would work something like...

Query for all entities A where property P starts with X

or

Query for all entities B where property P ends with X

Thanks, Matt

Answer 1

Seems you can't do it for the general case, but can do it for prefix searches (starts with):

http://stackoverflow.com/questions/1402769/wildcard-search-on-appengine-in-python

Answer 2

You can do a 'starts with' query by using inequality filters:

MyModel.all().filter('prop >=', prefix).filter('prop <', prefix + u'\ufffd')

Doing an 'ends with' query would require storing the reverse of the string, then applying the same tactic as above.