python - AttributeError: 'NoneType' object has no attribute 'sqlite_db' -

i don't understand how works. got code flaskr example. used work , doesn't.

i getting following error: attributeerror: 'nonetype' object has no attribute 'sqlite_db'

offending line: top.sqlite_db = sqlite_db

from champnotif_v2 import app flask import _app_ctx_stack, g import sqlite3  def get_db():     """opens new database connection if there none yet     current application context.     """     top = _app_ctx_stack.top     if not hasattr(top, 'sqlite_db'):         sqlite_db = sqlite3.connect(app.config['database'])         sqlite_db.row_factory = sqlite3.row         top.sqlite_db = sqlite_db      return top.sqlite_db 

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__init__.py

from flask import flask app = flask(__name__) app.config.from_pyfile('info.py')  import champnotif_v2.views 

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info.py

database = "freechamp.db" 

it appears top none, not whatever expecting be. therefore _app_ctx_stack.top must none top being set to. need work out why _app_ctx_stack.top none , fix that, or if expected add check before using top in way, example:

top = _app_ctx_stack.top ... if top not none:     top.sqlite_db = sqlite_db