pylint-django 2.0

A Pylint plugin to help Pylint understand the Django web framework

pylint-django

About

pylint-django is a Pylint plugin for improving code analysis when analysing code using Django. It is also used by the Prospector tool.

Installation

To install:

pip install pylint-django

WARNING: pylint-django will not install Django by default because this causes more trouble than good, see discussion. If you wish to automatically install the latest version of Django then:

pip install pylint-django[with_django]

otherwise sort out your testing environment and please DO NOT report issues about missing Django!

Usage

Ensure pylint-django is installed and on your path and then execute:

pylint --load-plugins pylint_django [..other options..] <path_to_your_sources>

Prospector

If you have prospector installed, then pylint-django will already be installed as a dependency, and will be activated automatically if Django is detected:

prospector [..other options..]

Features

• Prevents warnings about Django-generated attributes such as Model.objects or Views.request.

• Prevents warnings when using ForeignKey attributes (“Instance of ForeignKey has no <x> member”).

• Fixes pylint’s knowledge of the types of Model and Form field attributes

• Validates Model.__unicode__ methods.

• Meta informational classes on forms and models do not generate errors.

• Flags dangerous use of the exclude attribute in ModelForm.Meta.

Additional plugins

pylint_django.checkers.db_performance looks for migrations which add new model fields and these fields have a default value. According to Django docs this may have performance penalties especially on large tables. The prefered way is to add a new DB column with null=True because it will be created instantly and then possibly populate the table with the desired default values.

Only the last migration from a sub-directory will be examined!

This plugin is disabled by default! To enable it:

pylint --load-plugins pylint_django --load-plugins pylint_django.checkers.db_performance

Known issues

If you reference foreign-key models by their name (as string) pylint-django may not be able to find the model and will report issues because it has no idea what the underlying type of this field is. If your models.py itself is not importing the foreign-key class there’s probably some import problem (circular dependencies) preventing referencing the foreign-key class directly, in which case pylint-django can’t do a huge amount. If it’s just done for convenience that’s really up to you the developer to fix.

Contributing

Please feel free to add your name to the CONTRIBUTORS.rst file if you want to be credited when pull requests get merged. You can also add to the CHANGELOG.rst file if you wish, although we’ll also do that when merging.

Tests

The structure of the test package follows that from pylint itself.

It is fairly simple: create a module starting with func_ followed by a test name, and insert into it some code. The tests will run pylint against these modules. If the idea is that no messages now occur, then that is fine, just check to see if it works by running scripts/test.sh.

Ideally, add some pylint error suppression messages to the file to prevent spurious warnings, since these are all tiny little modules not designed to do anything so there’s no need to be perfect.

It is possible to make tests with expected error output, for example, if adding a new message or simply accepting that pylint is supposed to warn. A test_file_name.txt file contains a list of expected error messages in the format error-type:line number:class name or empty:1st line of detailed error text.

License

pylint-django is available under the GPLv2 license.

Changelog

Version 2.0 (25 July 2018)

• Requires pylint >= 2.0 which doesn’t support Python 2 anymore!

• Add modelform-uses-unicode check to flag dangerous use of the exclude attribute in ModelForm.Meta (Federico Bond).

Version 0.11.1 (25 May 2018), the DjangoCon Heidelberg edition

• Enable test case for urlpatterns variable which was previously disabled

• Disable unused-argument message for the request argument passed to view functions. Fix #155

• Add transformations for model_utils managers instead of special-casing them. Fix #160

Version 0.11 (18 April 2018), the TestCon Moscow edition

• New JsonResponseChecker that looks for common anti-patterns with http responses returning JSON. This includes:

  HttpResponse(json.dumps(data))
  
  HttpResponse(data, content_type='application/json')
  
  JsonResponse(data, content_type=...)

Version 0.10.0 (10 April 2018)

• Remove the compatibility layer for older astroid versions

• Make flake8 happy. Fix #102

• Fix: compatibility with Python < 3.6 caused by ModuleNotFoundError not available on older versions of Python (Juan Rial)

• Show README and CHANGELOG on PyPI. Fix #122

• Fix explicit unicode check with python_2_unicode_compatible base models (Federico Bond)

• Suppress not-an-iterable message for ‘objects’. Fix #117

• Teach pylint_django that objects.all() is subscriptable. Fix #144

• Suppress invalid-name for wsgi.application. Fix #77

• Add test for WSGIRequest.context. Closes #78

• Register transforms for FileField. Fix #60

• New checker pylint_django.checkers.db_performance. Enables checking of migrations and reports when there’s an AddField operation with a default value which may slow down applying migrations on large tables. This may also lead to production tables being locked while migrations are being applied. Fix #118

• Suppress no-member for factory.SubFactory objects. Useful when model factories use factory.SubFactory() for foreign key relations.

Version 0.9.4 (12 March 2018)

• Add an optional dependency on Django

• Fix the DjangoInstalledChecker so it can actually warn when Django isn’t available

• Fix #136 by adding automated build and sanity test scripts

Version 0.9.3 (removed from PyPI)

• Fix #133 and #134 by including package data when building wheel and tar.gz packages for PyPI (Joseph Herlant)

Version 0.9.2 (broken)

• Fix #129 - Move tests under site-packages/pylint_django (Mr. Senko)

• Fix #96 - List Django as a dependency (Mr. Senko)

Version 0.9.1 (26 Feb 2018)

• Fix #123 - Update links after the move to PyCQA (Mr. Senko)

• Add test for Meta class from django_tables2 (Mr. Senko)

• Fix flake8 complaints (Peter Bittner)

• Add missing .txt and .rc test files to MANIFEST.in (Joseph Herlant)

Version 0.9 (25 Jan 2018)

• Fix #120 - TypeError: ‘NamesConsumer’ object does not support indexing (Simone Basso)

• Fix #110 and #35 - resolve ForeignKey models specified as strings instead of class names (Mr. Senko)

Version 0.8.0 (20 Jan 2018)

• This is the last version to support Python 2. Issues a deprecation warning!

• #109, adding ‘urlpatterns’, ‘register’, ‘app_name’ to good names. Obsoletes #111, fixes #108 (Vinay Pai)

• Add ‘handler500’ to good names (Mr. Senko)

• #103: Support factory_boy’s DjangoModelFactory Meta class (Konstantinos Koukopoulos)

• #100: Fix E1101:Instance of ‘proxy‘ has no ‘format’ member’ when using .format() on a ugettext_lazy translation. Fixes #80 (canarduck)

• #99: Add tests and transforms for DurationField, fixes #95 (James M. Allen)

• #92: Add json field to WSGIRequest proxy (sjk4sc)

• #84: Add support for django.contrib.postgres.fields and UUIDField (Villiers Strauss)

• Stop testing with older Django versions. Currently testing with Django 1.11.x and 2.0

• Stop testing on Python 2, no functional changes in the source code though

• Update tests and require latest version of pylint (>=1.8), fixes #53, #97

• #81 Fix ‘duplicate-except’ false negative for except blocks which catch the DoesNotExist exception.

Version 0.7.4

• #88 Fixed builds with Django 1.10 (thanks to federicobond)

• #91 Fixed race condition when running with pylint parallel execution mode (thanks to jeremycarroll)

• #64 “Meta is old style class” now suppressed on BaseSerializer too (thanks to unklphil)

• #70 Updating to handle newer pylint/astroid versions (thanks to iXce)

Version 0.7.2

• #76 Better handling of mongoengine querysetmanager

• #73 #72 Make package zip safe to help fix some path problems

• #68 Suppressed invalid constant warning for “app_name” in urls.py

• #67 Fix view.args and view.kwargs

• #66 accessing _meta no longer causes a protected-access warning as this is a public API as of Django 1.8

• #65 Add support of mongoengine module.

• #59 Silence old-style-class for widget Meta

Version 0.7.1

• #52 - Fixed stupid mistake when using versioninfo

Version 0.7

• #51 - Fixed compatibility with pylint 1.5 / astroid 1.4.1

Version 0.6.1

• #43 - Foreign key ID access (somefk_id) does not raise an ‘attribute not found’ warning

• #31 - Support for custom model managers (thanks smirolo)

• #48 - Added support for django-restframework (thanks mbertolacci)

Version 0.6

• Pylint 1.4 dropped support for Python 2.6, therefore a constraint is added that pylint-django will only work with Python2.6 if pylint<=1.3 is installed

• #40 - pylint 1.4 warned about View and Model classes not having enough public methods; this is suppressed

• #37 - fixed an infinite loop when using astroid 1.3.3+

• #36 - no longer warning about lack of __unicode__ method on abstract model classes

• PR #34 - prevent warning about use of super() on ModelManager classes

Version 0.5.5

• PR #27 - better ForeignKey transforms, which now work when of the form othermodule.ModelClass. This also fixes a problem where an inferred type would be _Yes and pylint would fail

• PR #28 - better knowledge of ManyToManyField classes

Version 0.5.4

• Improved resiliance to inference failure when Django types cannot be inferred (which can happen if Django is not on the system path

Version 0.5.3

• Issue #25 Fixing cases where a module defines get as a method

Version 0.5.2

• Fixed a problem where type inference could get into an infinite loop

Version 0.5.1

• Removed usage of a Django object, as importing it caused Django to try to configure itself and thus throw an ImproperlyConfigured exception.

Version 0.5

• Issue #7 Improved handling of Django model fields

• Issue #10 No warning about missing unicode if the Django python3/2 compatability tools are used

• Issue #11 Improved handling of Django form fields

• Issue #12 Improved handling of Django ImageField and FileField objects

• Issue #14 Models which do not define unicode but whose parents do now have a new error (W5103) instead of incorrectly warning about no unicode being present.

• Issue #21 ForeignKey and OneToOneField fields on models are replaced with instance of the type they refer to in the AST, which allows pylint to generate correct warnings about attributes they may or may not have.

Version 0.3

• Python3 is now supported

• __unicode__ warning on models does not appear in Python3

Version 0.2

• Pylint now recognises BaseForm as an ancestor of Form and subclasses

• Improved Form support

• Issue #2 - a subclass of a Model or Form also has warnings about a Meta class suppressed.

• Issue #3 - Form and ModelForm subclasses no longer warn about Meta classes.