Flask and SQLAlchemy: No module named 'app' and NameError

Question

Noob level here. It seems my models.py file can't import the db object created in init.py, but a db file (blog.db) is still being created. Since I can't use my model class (Entry(db.Model)) to add to the database from within the console (the db object itself works in the console), I think I'm importing incorrectly from within the models.py. On Python3 (venv), Linux.

Dir structure (relevant folders only, ex. no cache):

/folder/
/folder/app/
/folder/app/__init__.py
/folder/app/models.py
/folder/config.py (only includes the sqlite uri naming variable)
/folder/fakepy/etc (venv, with flask and flask_sqlalchemy)
/folder/run.py (starts server fine, but does show that 'common' sql track modifications warning twice after a restart. normal?)

__init__.py:

#!fakepy/bin/python3 (error happens with or without shebang(s))
from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)

from app import models

models.py:

#!fakepy/bin/python3
from app import db
import re
import datetime

class Entry(db.Model):
    __tablename__ = "post"
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(80))
    slug = db.Column(db.String, unique=True)
    content = db.Column(db.Text)
    timestamp = db.Column(db.DateTime)
    def __init__(self, title, content, slug=None, timestamp=None):
        self.title = title
        self.content = content
        if slug is None:
            self.slug = re.sub('[^\w]+', '-', self.title.lower())
        if timestamp is None:
            timestamp = datetime.utcnow()
        self.timestamp = timestamp

config.py:

import os

basedir = os.path.abspath(os.path.dirname(__file__))

SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir, 'blog.db')

Database is created... (console opened at /folder/, blog.db created at /folder/):

>>> from app import db
>>> db.create_all()
>>>

ERROR: name 'Entry' is not defined when app is imported from console

(fakepy) cha0@skyrim:~/folder$ python3
Python 3.4.3+ (etc removed for brevity)
>>> from app import app
(common sql track modifications warning, removed it for brevity)
>>> Entry()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'Entry' is not defined
>>> 
>>> from app import models
>>> Entry()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'Entry' is not defined
 >>>
 >>> from app import Entry
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'Entry'
>>>

ERROR: No module named 'app' when models.py is ran directly.

(fakepy) cha0@skyrim:~/folder/app$ python3 models.py 
Traceback (most recent call last):
  File "models.py", line 2, in <module>
    from app import db
ImportError: No module named 'app'
(fakepy)

ERROR: No module named 'config' when init.py is ran directly. I think this may be a separate issue though.

python3 __init__.py
Traceback (most recent call last):
  File "/home/cha0/folder/fakepy/lib/python3.4/site-packages/werkzeug/utils.py", line 418, in import_string
    __import__(import_name)
ImportError: No module named 'config'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "__init__.py", line 6, in <module>
    app.config.from_object('config')
  File "/home/cha0/folder/fakepy/lib/python3.4/site-packages/flask/config.py", line 162, in from_object
    obj = import_string(obj)
  File "/home/cha0/folder/fakepy/lib/python3.4/site-packages/werkzeug/utils.py", line 443, in import_string
    sys.exc_info()[2])
  File "/home/cha0/folder/fakepy/lib/python3.4/site-packages/werkzeug/_compat.py", line 137, in reraise
    raise value.with_traceback(tb)
  File "/home/cha0/folder/fakepy/lib/python3.4/site-packages/werkzeug/utils.py", line 418, in import_string
    __import__(import_name)
werkzeug.utils.ImportStringError: import_string() failed for 'config'. 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;

Debugged import:

- 'config' not found.

Original exception:

ImportError: No module named 'config'

What I want:

From flask website.
>>>from yourapplication import User
>>> admin = User('admin', '[email protected]')

In my case-
>>>from app import Entry
>>>entry = Entry("title", "this is a post.")

is folder in your site-packages? have you ever run a setup.py for folder. also try before importing try adding import sys sys.path.insert(0, '/path/to/the/application') . Im thinking it should be more from folder.app.models import Entry — Busturdust
I tried your suggestion (both) but no go. I now realize though that I was activated into another venv and playing around with the files you see before I realized it.. I'm going to try recreating the folders/etc and copying/pasting the code, though I don't see why they would have messed things up here. — Cha0
possible that modules were loaded in one environment and not the other? For me I install a top level setup.py that installs all dependencies — Busturdust

Busturdust Busturdust · Accepted Answer · 2016-01-15T19:33:16

from app.models import Entry

You must import Entry from the models module of the app.

You may also need to add relative imports in your __init__ for any custom modules.

add to your __init__

from .models import *

edit: Another useful debugging tip - is to use the dir() function to see what is included in a package. In your case, the imports are working so you can run something like

dir(app)

With an argument, attempt to return a list of valid attributes for that object.

for instance here is a returned list for a flask app I wrote.if You cant see your moudle here, add the import.

Flask and SQLAlchemy: No module named 'app' and NameError

1 Answers