Why can't I import a model from a file containing import of any of the Google App Engine components?

Question

I'm attempting to build a simple Google App Engine App using TDD.

When I attempt to import my Customer model I get an error:

$ python functional_tests.py  
Traceback (most recent call last):  
  File "functional_tests.py", line 4, in <module>  
    from models import Customer    
  File "/Users/Bryan/work/GoogleAppEngine/dermalfillersecrets/models.py", line 1, in <module>  
    from google.appengine.ext import ndb    
ImportError: No module named google.appengine.ext

This is the code in model.py:

from google.appengine.ext import ndb  

class Customer(ndb.Model):  
    email =  ndb.StringProperty()   
    name = ndb.StringProperty(indexed=True)

This is the code from functional_tests.py:

from selenium import webdriver  
import unittest  
from models import Customer  

class NewVisitorTest(unittest.TestCase):

    def setUp(self):
        self.browser = webdriver.Firefox()
        self.browser.implicitly_wait(3)

    def tearDown(self):
        self.browser.quit()

    def test_quest_can_submit_contact_info(self):  
        self.browser.get('http://localhost:9080')  
        self.browser.find_element_by_name('id_name').send_keys("Kallie Wheelock")  
        self.browser.find_element_by_name('id_email').send_keys("kallie@gmail.com")  
        self.browser.find_element_by_name('submit').submit()  
        Customer.query(Customer.name("Kallie Wheelock")).delete()

score 1 · Accepted Answer · edited May 23 '17 at 12:23

Your specific problem is that you are not importing the app engine SDK to your sys path. sys.path.append("/usr/local/google_appengine") solves the ImportError.

But to solve your TDD challenge completely you have to use dev_appserver and testbed together with selenium. I took the solution proposed in https://stackoverflow.com/a/20986246/710851 and configured for your use case.

Before you call app engine libraries import the SDK and other libraries needed to your sys path:

import sys

sys.path.append("/usr/local/google_appengine")
sys.path.append("/usr/local/google_appengine/lib/yaml/lib")
sys.path.append("/usr/local/google_appengine/lib/webapp2-2.5.2")
sys.path.append("/usr/local/google_appengine/lib/django-1.5")
sys.path.append("/usr/local/google_appengine/lib/cherrypy")
sys.path.append("/usr/local/google_appengine/lib/concurrent")
sys.path.append("/usr/local/google_appengine/lib/docker")
sys.path.append("/usr/local/google_appengine/lib/requests")
sys.path.append("/usr/local/google_appengine/lib/websocket")
sys.path.append("/usr/local/google_appengine/lib/fancy_urllib")
sys.path.append("/usr/local/google_appengine/lib/antlr3")

Start dev_appserver, selenium and setup the testbed in your setUp method:

def setUp(self):

    # setup dev_appserver
    APP_CONFIGS = ['app.yaml']
    python_runtime._RUNTIME_ARGS = [
        sys.executable,
        os.path.join(os.path.dirname(dev_appserver.__file__),
                     '_python_runtime.py')
    ]
    options = devappserver2.PARSER.parse_args([
        '--admin_port', '0',
        '--port', '9080',
        '--datastore_path', ':memory:',
        '--logs_path', ':memory:',
        '--skip_sdk_update_check',
        '--',
    ] + APP_CONFIGS)
    server = devappserver2.DevelopmentServer()
    server.start(options)
    self.server = server

    # setup selenium
    self.browser = webdriver.Firefox()
    self.browser.implicitly_wait(3)

    # setup the testbed
    self.tb = testbed.Testbed()
    self.tb.setup_env(current_version_id='testbed.version')
    self.tb.activate()
    self.tb.init_user_stub()
    self.tb.init_datastore_v3_stub()
    self.tb.init_memcache_stub()

Deactivate everything in the tearDown method:

def tearDown(self):
    self.browser.quit()
    self.tb.deactivate()
    self.server.stop()

Complete example:

import os
import sys

sys.path.append("/usr/local/google_appengine")
sys.path.append("/usr/local/google_appengine/lib/yaml/lib")
sys.path.append("/usr/local/google_appengine/lib/webapp2-2.5.2")
sys.path.append("/usr/local/google_appengine/lib/django-1.5")
sys.path.append("/usr/local/google_appengine/lib/cherrypy")
sys.path.append("/usr/local/google_appengine/lib/concurrent")
sys.path.append("/usr/local/google_appengine/lib/docker")
sys.path.append("/usr/local/google_appengine/lib/requests")
sys.path.append("/usr/local/google_appengine/lib/websocket")
sys.path.append("/usr/local/google_appengine/lib/fancy_urllib")
sys.path.append("/usr/local/google_appengine/lib/antlr3")

import dev_appserver
from google.appengine.tools.devappserver2 import devappserver2
from google.appengine.tools.devappserver2 import python_runtime
from google.appengine.ext import testbed

from selenium import webdriver
import unittest
from models import Customer


class NewVisitorTest(unittest.TestCase):

    def setUp(self):

        # setup the dev_appserver
        APP_CONFIGS = ['app.yaml']
        python_runtime._RUNTIME_ARGS = [
            sys.executable,
            os.path.join(os.path.dirname(dev_appserver.__file__),
                         '_python_runtime.py')
        ]
        options = devappserver2.PARSER.parse_args([
            '--admin_port', '0',
            '--port', '9080',
            '--datastore_path', ':memory:',
            '--logs_path', ':memory:',
            '--skip_sdk_update_check',
            '--',
        ] + APP_CONFIGS)
        server = devappserver2.DevelopmentServer()
        server.start(options)
        self.server = server

        # setup selenium
        self.browser = webdriver.Firefox()
        self.browser.implicitly_wait(3)

        # setup the testbed
        self.tb = testbed.Testbed()
        self.tb.setup_env(current_version_id='testbed.version')
        self.tb.activate()
        self.tb.init_user_stub()
        self.tb.init_datastore_v3_stub()
        self.tb.init_memcache_stub()

    def tearDown(self):
        self.browser.quit()
        self.tb.deactivate()
        self.server.stop()

    def test_quest_can_submit_contact_info(self):
        self.browser.get('http://localhost:9080')
        self.browser.find_element_by_name('id_name').send_keys("Kallie Wheelock")
        self.browser.find_element_by_name('id_email').send_keys("kallie@gmail.com")
        self.browser.find_element_by_name('submit').submit()
        Customer.query(Customer.name("Kallie Wheelock")).delete()

score 0 · Answer 2 · answered Jan 04 '16 at 14:30

In the latest version make sure to add this line

 if 'google' in sys.modules:
    del sys.modules['google']

Full Example below

import sys
sys.path.append('/usr/local/google_appengine/')
sys.path.append('/usr/local/google_appengine/lib/yaml/lib/')

  if 'google' in sys.modules:
      del sys.modules['google']

Why can't I import a model from a file containing import of any of the Google App Engine components?

2 Answers2

Complete example: