django/docs/internals/contributing/writing-code/submitting-patches.txt

==================
Submitting patches
==================

We're always grateful for patches to Django's code. Indeed, bug reports
with associated patches will get fixed *far* more quickly than those
without patches.

Typo fixes and trivial documentation changes
--------------------------------------------

If you are fixing a really trivial issue, for example changing a word in the
documentation, the preferred way to provide the patch is using GitHub pull
requests without a Trac ticket. Trac tickets are still acceptable.

See the :doc:`working-with-git` for more details on how to use pull requests.

"Claiming" tickets
------------------

In an open-source project with hundreds of contributors around the world, it's
important to manage communication efficiently so that work doesn't get
duplicated and contributors can be as effective as possible.

Hence, our policy is for contributors to "claim" tickets in order to let other
developers know that a particular bug or feature is being worked on.

If you have identified a contribution you want to make and you're capable of
fixing it (as measured by your coding ability, knowledge of Django internals
and time availability), claim it by following these steps:

* `Create an account`_ to use in our ticket system. If you have an account
  but have forgotten your password, you can reset it using the
  `password reset page`_.

* If a ticket for this issue doesn't exist yet, create one in our
  `ticket tracker`_.

* If a ticket for this issue already exists, make sure nobody else has
  claimed it. To do this, look at the "Owned by" section of the ticket.
  If it's assigned to "nobody," then it's available to be claimed.
  Otherwise, somebody else is working on this ticket, and you either find
  another bug/feature to work on, or contact the developer working on the
  ticket to offer your help.

* Log into your account, if you haven't already, by clicking "Login" in
  the upper right of the ticket page.

* Claim the ticket:

  1. click the "assign to myself" radio button under "Action" near the bottom of the
     page,
  2. then click "Submit changes."

.. note::
    The Django software foundation requests that anyone contributing more than
    a trivial patch to Django sign and submit a `Contributor License
    Agreement`_, this ensures that the Django Software Foundation has clear
    license to all contributions allowing for a clear license for all users.

.. _Create an account: https://www.djangoproject.com/accounts/register/
.. _password reset page: https://www.djangoproject.com/accounts/password/reset/
.. _Contributor License Agreement: https://www.djangoproject.com/foundation/cla/

Ticket claimers' responsibility
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Once you've claimed a ticket, you have a responsibility to work on that ticket
in a reasonably timely fashion. If you don't have time to work on it, either
unclaim it or don't claim it in the first place!

If there's no sign of progress on a particular claimed ticket for a week or
two, another developer may ask you to relinquish the ticket claim so that it's
no longer monopolized and somebody else can claim it.

If you've claimed a ticket and it's taking a long time (days or weeks) to code,
keep everybody updated by posting comments on the ticket. If you don't provide
regular updates, and you don't respond to a request for a progress report,
your claim on the ticket may be revoked.

As always, more communication is better than less communication!

Which tickets should be claimed?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Of course, going through the steps of claiming tickets is overkill in some
cases.

In the case of small changes, such as typos in the documentation or
small bugs that will only take a few minutes to fix, you don't need to jump
through the hoops of claiming tickets. Just submit your patch and be done with
it.

Of course, it is *always* acceptable, regardless whether someone has claimed it
or not, to submit patches to a ticket if you happen to have a patch ready.

.. _patch-style:

Patch style
-----------

Make sure that any contribution you do fulfills at least the following
requirements:

* The code required to fix a problem or add a feature is an essential part
  of a patch, but it is not the only part. A good patch should also include a
  :doc:`regression test <unit-tests>` to validate the behavior that has been
  fixed and to prevent the problem from arising again. Also, if some tickets
  are relevant to the code that you've written, mention the ticket numbers in
  some comments in the test so that one can easily trace back the relevant
  discussions after your patch gets committed, and the tickets get closed.

* If the code associated with a patch adds a new feature, or modifies
  behavior of an existing feature, the patch should also contain
  documentation.

You can use either GitHub branches and pull requests or direct patches
to publish your work. If you use the Git workflow, then you should
announce your branch in the ticket by including a link to your branch.
When you think your work is ready to be merged in create a pull request.

See the :doc:`working-with-git` documentation for mode details.

You can also use patches in Trac. When using this style, follow these
guidelines.

* Submit patches in the format returned by the ``git diff`` command.
  An exception is for code changes that are described more clearly in
  plain English than in code. Indentation is the most common example; it's
  hard to read patches when the only difference in code is that it's
  indented.

* Attach patches to a ticket in the `ticket tracker`_, using the "attach
  file" button. Please *don't* put the patch in the ticket description
  or comment unless it's a single line patch.

* Name the patch file with a ``.diff`` extension; this will let the ticket
  tracker apply correct syntax highlighting, which is quite helpful.

Regardless of the way you submit your work, follow these steps.

* Make sure your code matches our :doc:`coding-style`.

* Check the "Has patch" box on the ticket details. This will make it
  obvious that the ticket includes a patch, and it will add the ticket to
  the `list of tickets with patches`_.


Non-trivial patches
-------------------

A "non-trivial" patch is one that is more than a simple bug fix. It's a patch
that introduces Django functionality and makes some sort of design decision.

If you provide a non-trivial patch, include evidence that alternatives have
been discussed on |django-developers|.

If you're not sure whether your patch should be considered non-trivial, just
ask.

.. _deprecating-a-feature:

Deprecating a feature
---------------------

There are a couple reasons that code in Django might be deprecated:

* If a feature has been improved or modified in a backwards-incompatible way,
  the old feature or behavior will be deprecated.

* Sometimes Django will include a backport of a Python library that's not
  included in a version of Python that Django currently supports. When Django
  no longer needs to support the older version of Python that doesn't include
  the library, the library will be deprecated in Django.

As the :ref:`deprecation policy<internal-release-deprecation-policy>` describes,
the first release of Django that deprecates a feature (``A.B``) should raise a
``RemovedInDjangoXXWarning`` (where XX is the Django version where the feature
will be removed) when the deprecated feature is invoked. Assuming we have good
test coverage, these warnings are converted to errors when :ref:`running the
test suite <running-unit-tests>` with warnings enabled:
``python -Wall runtests.py``. Thus, when adding a ``RemovedInDjangoXXWarning``
you need to eliminate or silence any warnings generated when running the tests.

The first step is to remove any use of the deprecated behavior by Django itself.
Next you can silence warnings in tests that actually test the deprecated
behavior by using the ``ignore_warnings`` decorator, either at the test or class
level:

#) In a particular test::

    from django.test import ignore_warnings
    from django.utils.deprecation import RemovedInDjangoXXWarning

    @ignore_warnings(category=RemovedInDjangoXXWarning)
    def test_foo(self):
        ...

#) For an entire test case::

    from django.test import ignore_warnings
    from django.utils.deprecation import RemovedInDjangoXXWarning

    @ignore_warnings(category=RemovedInDjangoXXWarning)
    class MyDeprecatedTests(unittest.TestCase):
        ...

.. versionchanged:: 1.8

    Previous versions of Django had some ``Ignore*DeprecationWarningsMixin``
    classes to prevent warnings from appearing. These have been replaced by the
    ``ignore_warnings`` decorator.

You can also add a test for the deprecation warning. You'll have to disable the
"warning as error" behavior in your test by doing::

    import warnings

    def test_foo_deprecation_warning(self):
        with warnings.catch_warnings(record=True) as warns:
            warnings.simplefilter('always')  # prevent warnings from appearing as errors
            # invoke deprecated behavior

        self.assertEqual(len(warns), 1)
        msg = str(warns[0].message)
        self.assertEqual(msg, 'Expected deprecation message')

Finally, there are a couple of updates to Django's documentation to make:

#) If the existing feature is documented, mark it deprecated in documentation
   using the ``.. deprecated:: A.B`` annotation. Include a short description
   and a note about the upgrade path if applicable.

#) Add a description of the deprecated behavior, and the upgrade path if
   applicable, to the current release notes (``docs/releases/A.B.txt``) under
   the "Features deprecated in A.B" heading.

#) Add an entry in the deprecation timeline (``docs/internals/deprecation.txt``)
   under the ``A.B+2`` version describing what code will be removed.

Once you have completed these steps, you are finished with the deprecation.
In each major release, all ``RemovedInDjangoXXWarning``\s matching the new
version are removed.

Javascript patches
------------------

Django's admin system leverages the jQuery framework to increase the
capabilities of the admin interface. In conjunction, there is an emphasis on
admin javascript performance and minimizing overall admin media file size.
Serving compressed or "minified" versions of javascript files is considered
best practice in this regard.

To that end, patches for javascript files should include both the original
code for future development (e.g. ``foo.js``), and a compressed version for
production use (e.g. ``foo.min.js``). Any links to the file in the codebase
should point to the compressed version.

Compressing JavaScript
~~~~~~~~~~~~~~~~~~~~~~

To simplify the process of providing optimized javascript code, Django
includes a handy python script which should be used to create a "minified"
version. To run it::

    python django/contrib/admin/bin/compress.py

Behind the scenes, ``compress.py`` is a front-end for Google's
`Closure Compiler`_ which is written in Java. However, the Closure Compiler
library is not bundled with Django directly, so those wishing to contribute
complete javascript patches will need to download and install the library
independently. The Closure Compiler library requires `Java`_ 7 or higher.

Please don't forget to run ``compress.py`` and include the ``diff`` of the
minified scripts when submitting patches for Django's javascript.

.. _Closure Compiler: https://developers.google.com/closure/compiler/
.. _list of tickets with patches: https://code.djangoproject.com/query?status=new&status=assigned&status=reopened&has_patch=1&order=priority
.. _ticket tracker: https://code.djangoproject.com/newticket
.. _Java: https://www.java.com

.. _patch-review-checklist:

Patch review checklist
----------------------

Use this checklist to review a pull request. If you are reviewing a pull
request that is not your own and it passes all the criteria below, please set
the "Triage Stage" on the corresponding Trac ticket to "Ready for checkin".
If you've left comments for improvement on the pull request, please tick the
appropriate flags on the Trac ticket based on the results of your review:
"Patch needs improvement", "Needs documentation", and/or "Needs tests". As time
and interest permits, core developers do final reviews of "Ready for checkin"
tickets and will either commit the patch or bump it back to "Accepted" if
further works need to be done. If you're looking to become a core developer,
doing thorough reviews of patches is a great way to earn trust.

Looking for a patch to review? Check out the "Patches needing review" section
of the `Django Development Dashboard <https://dashboard.djangoproject.com/>`_.
Looking to get your patch reviewed? Ensure the Trac flags on the ticket are
set so that the ticket appears in that queue.

Documentation
~~~~~~~~~~~~~

* Does the documentation build without any errors (``make html``, or
  ``make.bat html`` on Windows, from the ``docs`` directory)?
* Does the documentation follow the writing style guidelines in
  :doc:`/internals/contributing/writing-documentation`?
* Are there any :ref:`spelling errors <documentation-spelling-check>`?

Bugs
~~~~

* Is there a proper regression test (the test should fail before the fix
  is applied)?

New Features
~~~~~~~~~~~~

* Are there tests to "exercise" all of the new code?
* Is there a release note in ``docs/releases/A.B.txt``?
* Is there documentation for the feature and is it annotated appropriately with
  ``.. versionadded:: A.B`` or ``.. versionchanged:: A.B``?

Deprecating a feature
~~~~~~~~~~~~~~~~~~~~~

See the :ref:`deprecating-a-feature` guide.

All code changes
~~~~~~~~~~~~~~~~

* Does the :doc:`coding style
  </internals/contributing/writing-code/coding-style>` conform to our
  guidelines? Are there any ``flake8`` errors?
* If the change is backwards incompatible in any way, is there a note
  in the release notes (``docs/releases/A.B.txt``)?
* Is Django's test suite passing? Ask in ``#django-dev`` for a core dev
  to build the pull request against our continuous integration server.

All tickets
~~~~~~~~~~~

* Is the pull request a single squashed commit with a message that follows our
  :ref:`commit message format <committing-guidelines>`?
* Are you the patch author and a new contributor? Please add yourself to the
  ``AUTHORS`` file and submit a `Contributor License Agreement`_.

.. _Contributor License Agreement: https://www.djangoproject.com/foundation/cla/