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import of Python class from module in package

My structure looks something like this:
project/->
app.py
checker/->
exc.py
anc.py
My files are simple:
# app.py
from checker.exc import ExampleClass
# checker/exc.py:
from anc import AnotherClass
class ExampleClass(AnotherClass):
print('Example')
# checker/anc.py:
class AnotherClass:
print('AAAA')
When I run exc.py inside checker folder everything works ok, same when
I run app.py with module from package checker everything works perfect.
But when I run app.py which uses class from checker.exc, and exc need anc. I have an error ModuleNotFoundError: No module named anc

Realise this is a duct tape solution.
Change exc.py to:
try:
from anc import AnotherClass
print('abs import')
except ModuleNotFoundError:
from .anc import AnotherClass
print('rel import')
class ExampleClass(AnotherClass):
print('Example')
That way you can use absolute import when debugging, for instance, but rely on relative import when importing it running app.py on it's own.
The order in which you attempt to import them should reflect the expected use, with the one most expected to be used being attempted first. The error is the same if you switch the attempts.

Since the code is being run from the project folder, in order for exc.py to find anc.py you need to change exc.py to the following:
from .anc import AnotherClass
class ExampleClass(AnotherClass):
print('Example')
As berna1111's comment suggests, this may cause problems when running exc.py directly.

Error trying to import between python files

I have a basic parser app I'm building in Python. I monitors a folder and imports files when they are dropped there. I have a MongoDB that I'm trying to save the imports to. There's almost nothing to it. The problem happens when I try to include one of my class/mongo-document files. I'm sure it's a simple syntax issue I don't understand. I have all my requirements installed, and I'm running this in an virtual env. This is my first python app though, so it's likely something I'm not seeing.
My file structure is
application.py
requirements.txt
__init__.py
-services
parser.py
__init__.py
-models
hl7message.py
__init__.py
Here is application.py
from mongoengine import connect
import os, os.path, time
from services import parser
db = connect('testdb')
dr = 'C:\\Imports\\Processed'
def processimports():
while True:
files = os.listdir(dr)
print(str(len(files)) + ' files found')
for f in files:
msg = open(dr + '\\' + f).read().replace('\n', '\r')
parser.parse_message(msg)
print('waiting')
time.sleep(10)
processimports()
requirements.txt
mongoengine
hl7
parser.py
import hl7
from models import hl7message
def parse_message(message):
m = hl7.parse(str(message))
h = hl7message()
hl7message.py
from utilities import common
from application import db
import mongoengine
class Hl7message(db.Document):
message_type = db.StringField(db_field="m_typ")
created = db.IntField(db_field="cr")
message = db.StringField(db_field="m")
If I don't include the hl7message class in the parser.py it runs fine, but as soon as I include it I get the error, so I'm sure it has something to do with that file. The error message though isn't to helpful. I don't know if I've got myself into some kind of include loop or something.
Sorry, stack trace is below
Traceback (most recent call last):
File "C:/OneDrive/Dev/3/Importer/application.py", line 3, in <module>
from services import parser
File "C:\OneDrive\Dev\3\Importer\services\parser.py", line 2, in <module>
from models import hl7message
File "C:\OneDrive\Dev\3\Importer\models\hl7message.py", line 2, in <module>
from application import db
File "C:\OneDrive\Dev\3\Importer\application.py", line 23, in <module>
processimports()
File "C:\OneDrive\Dev\3\Importer\application.py", line 17, in processimports
parser.parse_message(msg)
AttributeError: module 'services.parser' has no attribute 'parse_message'

This is a circular import issue. Application.py imports parser, which imports h17 which imports h17message, which imports application which runs processimports before the whole code of the parser module has been run.
It seems to me that service modules should not import application. You could create a new module common.py containing the line db = connect('testdb') and import db from common both in application.py and in h17message.

More elegant solution for python imports across app/tests?

I'm trying to keep my code reasonably organized by putting tests in a separate directory from my app. However, imports work either for the app or for the tests, but not both. Here's a contrived example that illustrates my current problem:
myapp/
app/
main.py
settings.py
moods.py
test/
test_moods.py
Contents of files as follows:
main.py
import settings
from moods import Moods
words = Moods(settings.EXAMPLE)
print(words.excited())
settings.py
EXAMPLE = "Wow$ Python$"
DELIM = "$"
moods.py
import settings
class Moods:
def __init__(self, text):
self.text = text
def excited(self):
return self.text.replace(settings.DELIM, "!!!")
test_moods.py
import sys, os, unittest
sys.path.insert(0, os.path.abspath('..'))
from app.moods import Moods
class TestMood(unittest.TestCase):
def setUp(self):
self.words = Moods("Broken imports$ So sad$")
def test_mood(self):
self.assertEqual(self.words.excited(), "Broken imports!!! So sad!!!")
with self.assertRaises(AttributeError):
self.words.angry()
if __name__ == "__main__":
unittest.main()
In the current state, from myapp/ I can run the following successfully:
>> python3 app/main.py
Wow!!! Python!!!
But when I try to run tests, the import fails in moods.py:
>> python3 -m unittest discover test/
ImportError: Failed to import test module: test_moods
[ stack trace here pointing to first line of moods.py ]
ImportError: No module named 'settings'
If I modify line 1 of moods.py to read from app import settings, the test will pass, but normal execution of the app fails because it sees no module app.
The only solutions I can think of are
Putting the tests in the same directory as the code (which I was trying to avoid)
Adding the sys.path.insert(0, os.path.abspath('..')) to each file in my app to make the imports work the same as the test ones do (which seems messy)
Is there are more elegant way to solve this import problem?

You should have both app and test directory in PYTHONPATH.
One way is to replace this:
sys.path.insert(0, os.path.abspath('..'))
from app.moods import Moods
with this:
sys.path.insert(0, os.path.abspath('../app'))
from moods import Moods
Or you can set the PYTHONPATH environament variable before running the tests.
Why? Because when you run main.py, then app is in the path, not app/.., so you want to have the same when running tests.

Django: where is settings.py looking for imports, and why?

I have a Django app with a common directory structure:
project
---manage.py
---app
---__init__.py
---settings.py
---settings_secret.py
---a bunch of other files for the app itself
That settings_secret.py file contains variables from secrets.py which I do not want to send to github. For some reason, I cannot seem to import it into settings.py. First 5 lines of settings.py:
# Django settings for project.
DEBUG = True
TEMPLATE_DEBUG = DEBUG
import os
from settings_secret import *
Which fails with the partial stacktrace:
File "/foo/bar/project/app/settings.py", line 5, in <module> from settings_secret import *
ImportError: No module named 'settings_secret'
To debug, I created a test file inside /project/ like so:
from settings_secret import *
print(VARIABLE_FROM_SETTINGS_SECRET)
Which worked like a charm. So clearly, settings.py isn't looking in the right place for settings_secret. So where is it looking?

In settings.py, you should do: from .settings_secret import *
It works with the . because the proper syntax is supposed to be:
from app.settings_secret import *
Removing the app is shorthand coding, but the same principle applies. You need to tell Django to look for the directory (app), and then you are specifying which file in that directory to look for.
If you just did, from settings_secret import *, you are telling Django to look for the directory settings_secret, which doesn't exist.
Does that make sense to you?

New django project: Cannot import name connections

I'm having a problem with Django. If you could help me, I'd very much appreciate it.
So, I've found lots of people with a similar problem, but none of the "solutions" work for me. I'm learning how to use django and I've successfully installed it.
But, I get an error when executing the import from the init.py file:
from django.db import connections
Here's the error:
raise ImportError("Could not import settings '%s' (Is it on sys.path?): %s" % (self.SETTINGS_MODULE, e))
ImportError: Could not import settings 'TestProject.settings' (Is it on sys.path?): cannot import name connections
The containing django folder is included on my PYTHONPATH, and my file structure looks like this:
TestProject
--manage.py
--TestProject
----__init__.py
----settings.py
etc.
This is my manage.py file:
#!/usr/bin/env python import os import sys
if __name__ == "__main__":
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "TestProject.settings")
from django.core.management import execute_from_command_line
execute_from_command_line(sys.argv)
I don't really know how to troubleshoot this. I'm also new to Python, so forgive me if this is completely obvious to someone else.
Thanks for your help.

This is a weird quirk indeed. I found the following to work in my program:
Import django settings.
Set the default environment.
ACCESS e.g. SITE_ID (or another property, but just use e.g. SITE_ID) through settings.
Finally, you should be able to import.
E.g.
from django.conf import settings
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myapp.settings")
settings.SITE_ID
or use another variable like DEBUG; note.. this line does nothing.. it just accesses the settings and seems to 'activate' the environment. You could also do a simple print statement like print settings.SITE_ID, but that's not necessary.)
from myapp.models import MyModel, MyOtherModel
If you do everything in that order.. well it worked for me! The magic happens when you access an actual setting before you do the import of a model.
I think this might be a bug/error in Django 1.5