importing google.cloud.datastore not working - python-2.7

Question

I am working in pycharm(in windows) environment.
I am building a website to send query to datastore and display values. I also have data under kind="SpecialTest" that is automatically saved through Node.js. Now I wanted to Query the data from Python.
I installed google-cloud-datastore from command line.
But I can't establish connection to datastore.
My code:
from google.cloud import datastore
cli=datastore.Client(project="My_project_I")
query4= cli.query(kind="SpecialTest").order('Published_at')
print query4
My result:
Internal Server Error
The server has either erred or is incapable of performing the requested operation.
Traceback (most recent call last):
File "C:\Program Files\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1535, in __call__
rv = self.handle_exception(request, response, e)
File "C:\Program Files\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1529, in __call__
rv = self.router.dispatch(request, response)
File "C:\Program Files\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1272, in default_dispatcher
self.handlers[handler] = handler = import_string(handler)
File "C:\Program Files\Google\google_appengine\lib\webapp2-2.5.2\webapp2.py", line 1850, in import_string
return getattr(__import__(module, None, None, [obj]), obj)
File "C:\Users\Harry\workspace\www\app\account.py", line 11, in <module>
from google.cloud import datastore
File "C:\Python27\lib\site-packages\google\cloud\datastore\__init__.py", line 60, in <module>
from google.cloud.datastore.batch import Batch
File "C:\Python27\lib\site-packages\google\cloud\datastore\batch.py", line 24, in <module>
from google.cloud.datastore import helpers
File "C:\Python27\lib\site-packages\google\cloud\datastore\helpers.py", line 23, in <module>
from google.protobuf import struct_pb2
ImportStringError: import_string() failed for 'app.account.UserAccount'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
Original exception:
ImportError: No module named protobuf
Debugged import:
- 'app' found in 'C:\\Users\\Harry\\workspace\\www\\app\\__init__.pyc'.
- 'app.account' not found.

Answer 1

The datastore client library is not supplied by GAE, you need to install/vendor it into your application (different method than for a standalone script).
Alternatively you can use the GAE-specific datastore library - it's actually recommended as it offers some advantages over the general purpose one. From Google App Engine Standard Environment Client Libraries:
Integrate Cloud Datastore with your App Engine Standard Environment
applications by using the App Engine client libraries.
...
Python Google Datastore NDB Client Library
Note: For App Engine applications that are written in Python, the Google Datastore DB Client Library is no longer recommended; use the
Google Datastore NDB Client Library instead.