Getting objects from the App Engine data store based on URL parameters

handler.py

from google.appengine.ext import db
import webapp2

from models.my_model import MyModel


class Handler(webapp2.RequestHandler):
  def get(self):
    try:
      my_model = MyModel.get(self.request.get('my_model_key'))
    except db.BadKeyError:
      my_model = None
    
    if not my_model:
      return self.error(404)