Interested in giving back to the community a little? Maybe you’ve found a bug\nin Django that you’d like to see fixed, or maybe there’s a small feature you\nwant added.
\nContributing back to Django itself is the best way to see your own concerns\naddressed. This may seem daunting at first, but it’s really pretty simple.\nWe’ll walk you through the entire process, so you can learn by example.
\nFor this tutorial, we expect that you have at least a basic understanding of\nhow Django works. This means you should be comfortable going through the\nexisting tutorials on writing your first Django app.\nIn addition, you should have a good understanding of Python itself. But if you\ndon’t, Dive Into Python is a fantastic (and free) online book for\nbeginning Python programmers.
\nThose of you who are unfamiliar with version control systems and Trac will find\nthat this tutorial and its links include just enough information to get started.\nHowever, you’ll probably want to read some more about these different tools if\nyou plan on contributing to Django regularly.
\nFor the most part though, this tutorial tries to explain as much as possible,\nso that it can be of use to the widest audience.
\n\nWe’ll be walking you through contributing a patch to Django for the first time.\nBy the end of this tutorial, you should have a basic understanding of both the\ntools and the processes involved. Specifically, we’ll be covering the following:
\nInstalling Git.
How to download a development copy of Django.
Running Django’s test suite.
Writing a test for your patch.
Writing the code for your patch.
Testing your patch.
Submitting a pull request.
Where to look for more information.
Once you’re done with the tutorial, you can look through the rest of\nDjango’s documentation on contributing.\nIt contains lots of great information and is a must read for anyone who’d like\nto become a regular contributor to Django. If you’ve got questions, it’s\nprobably got the answers.
\n\n\nAs a contributor, you can help us keep the Django community open and inclusive.\nPlease read and follow our Code of Conduct.
\nFor this tutorial, you’ll need Git installed to download the current\ndevelopment version of Django and to generate patch files for the changes you\nmake.
\nTo check whether or not you have Git installed, enter git into the command\nline. If you get messages saying that this command could not be found, you’ll\nhave to download and install it, see Git’s download page.
If you’re not that familiar with Git, you can always find out more about its\ncommands (once it’s installed) by typing git help into the command line.
The first step to contributing to Django is to get a copy of the source code.\nFirst, fork Django on GitHub. Then,\nfrom the command line, use the cd command to navigate to the directory\nwhere you’ll want your local copy of Django to live.
Download the Django source code repository using the following command:
\n$ git clone git@github.com:YourGitHubName/django.git\nNow that you have a local copy of Django, you can install it just like you would\ninstall any package using pip. The most convenient way to do so is by using\na virtual environment (or virtualenv) which is a feature built into Python\nthat allows you to keep a separate directory of installed packages for each of\nyour projects so that they don’t interfere with each other.
It’s a good idea to keep all your virtualenvs in one place, for example in\n.virtualenvs/ in your home directory. Create it if it doesn’t exist yet:
$ mkdir ~/.virtualenvs\nNow create a new virtualenv by running:
\n$ python3 -m venv ~/.virtualenvs/djangodev\nThe path is where the new environment will be saved on your computer.
\n\n\nThe final step in setting up your virtualenv is to activate it:
\n$ source ~/.virtualenvs/djangodev/bin/activate\nIf the source command is not available, you can try using a dot instead:
$ . ~/.virtualenvs/djangodev/bin/activate\nYou have to activate the virtualenv whenever you open a new terminal window.\nvirtualenvwrapper is a useful tool for making this more convenient.
\nAnything you install through pip from now on will be installed in your new\nvirtualenv, isolated from other environments and system-wide packages. Also, the\nname of the currently activated virtualenv is displayed on the command line to\nhelp you keep track of which one you are using. Go ahead and install the\npreviously cloned copy of Django:
$ pip install -e /path/to/your/local/clone/django/\nThe installed version of Django is now pointing at your local copy. You will\nimmediately see any changes you make to it, which is of great help when writing\nyour first patch.
\nFor this tutorial, we’ll be using ticket #24788 as a case study, so\nwe’ll rewind Django’s version history in git to before that ticket’s patch was\napplied. This will allow us to go through all of the steps involved in writing\nthat patch from scratch, including running Django’s test suite.
\nKeep in mind that while we’ll be using an older revision of Django’s trunk\nfor the purposes of the tutorial below, you should always use the current\ndevelopment revision of Django when working on your own patch for a ticket!
\n\nNavigate into Django’s root directory (that’s the one that contains django,\ndocs, tests, AUTHORS, etc.). You can then check out the older\nrevision of Django that we’ll be using in the tutorial below:
$ git checkout 4ccfc4439a7add24f8db4ef3960d02ef8ae09887\nWhen contributing to Django it’s very important that your code changes don’t\nintroduce bugs into other areas of Django. One way to check that Django still\nworks after you make your changes is by running Django’s test suite. If all\nthe tests still pass, then you can be reasonably sure that your changes\nhaven’t completely broken Django. If you’ve never run Django’s test suite\nbefore, it’s a good idea to run it once beforehand just to get familiar with\nwhat its output is supposed to look like.
\nBefore running the test suite, install its dependencies by first cd-ing\ninto the Django tests/ directory and then running:
$ pip install -r requirements/py3.txt\nIf you encounter an error during the installation, your system might be missing\na dependency for one or more of the Python packages. Consult the failing\npackage’s documentation or search the Web with the error message that you\nencounter.
\nNow we are ready to run the test suite. If you’re using GNU/Linux, macOS, or\nsome other flavor of Unix, run:
\n$ ./runtests.py\nNow sit back and relax. Django’s entire test suite has over 9,600 different\ntests, so it can take anywhere from 5 to 15 minutes to run, depending on the\nspeed of your computer.
\nWhile Django’s test suite is running, you’ll see a stream of characters\nrepresenting the status of each test as it’s run. E indicates that an error\nwas raised during a test, and F indicates that a test’s assertions failed.\nBoth of these are considered to be test failures. Meanwhile, x and s\nindicated expected failures and skipped tests, respectively. Dots indicate\npassing tests.
Skipped tests are typically due to missing external libraries required to run\nthe test; see Running all the tests for a list of dependencies\nand be sure to install any for tests related to the changes you are making (we\nwon’t need any for this tutorial). Some tests are specific to a particular\ndatabase backend and will be skipped if not testing with that backend. SQLite\nis the database backend for the default settings. To run the tests using a\ndifferent backend, see Using another settings module.
\nOnce the tests complete, you should be greeted with a message informing you\nwhether the test suite passed or failed. Since you haven’t yet made any changes\nto Django’s code, the entire test suite should pass. If you get failures or\nerrors make sure you’ve followed all of the previous steps properly. See\nRunning the unit tests for more information. If you’re using Python 3.5+,\nthere will be a couple failures related to deprecation warnings that you can\nignore. These failures have since been fixed in Django.
\nNote that the latest Django trunk may not always be stable. When developing\nagainst trunk, you can check Django’s continuous integration builds to\ndetermine if the failures are specific to your machine or if they are also\npresent in Django’s official builds. If you click to view a particular build,\nyou can view the “Configuration Matrix” which shows failures broken down by\nPython version and database backend.
\n\nBefore making any changes, create a new branch for the ticket:
\n$ git checkout -b ticket_24788\nYou can choose any name that you want for the branch, “ticket_24788” is an\nexample. All changes made in this branch will be specific to the ticket and\nwon’t affect the main copy of the code that we cloned earlier.
\nIn most cases, for a patch to be accepted into Django it has to include tests.\nFor bug fix patches, this means writing a regression test to ensure that the\nbug is never reintroduced into Django later on. A regression test should be\nwritten in such a way that it will fail while the bug still exists and pass\nonce the bug has been fixed. For patches containing new features, you’ll need\nto include tests which ensure that the new features are working correctly.\nThey too should fail when the new feature is not present, and then pass once it\nhas been implemented.
\nA good way to do this is to write your new tests first, before making any\nchanges to the code. This style of development is called\ntest-driven development and can be applied to both entire projects and\nsingle patches. After writing your tests, you then run them to make sure that\nthey do indeed fail (since you haven’t fixed that bug or added that feature\nyet). If your new tests don’t fail, you’ll need to fix them so that they do.\nAfter all, a regression test that passes regardless of whether a bug is present\nis not very helpful at preventing that bug from reoccurring down the road.
\nNow for our hands-on example.
\nTicket #24788 proposes a small feature addition: the ability to\nspecify the class level attribute prefix on Form classes, so that:
[…] forms which ship with apps could effectively namespace themselves such\nthat N overlapping form fields could be POSTed at once and resolved to the\ncorrect form.\nIn order to resolve this ticket, we’ll add a prefix attribute to the\nBaseForm class. When creating instances of this class, passing a prefix to\nthe __init__() method will still set that prefix on the created instance.\nBut not passing a prefix (or passing None) will use the class-level prefix.\nBefore we make those changes though, we’re going to write a couple tests to\nverify that our modification functions correctly and continues to function\ncorrectly in the future.
Navigate to Django’s tests/forms_tests/tests/ folder and open the\ntest_forms.py file. Add the following code on line 1674 right before the\ntest_forms_with_null_boolean function:
def test_class_prefix(self):\n # Prefix can be also specified at the class level.\n class Person(Form):\n first_name = CharField()\n prefix = 'foo'\n\n p = Person()\n self.assertEqual(p.prefix, 'foo')\n\n p = Person(prefix='bar')\n self.assertEqual(p.prefix, 'bar')\nThis new test checks that setting a class level prefix works as expected, and\nthat passing a prefix parameter when creating an instance still works too.
Remember that we haven’t actually made any modifications to BaseForm yet,\nso our tests are going to fail. Let’s run all the tests in the forms_tests\nfolder to make sure that’s really what happens. From the command line, cd\ninto the Django tests/ directory and run:
$ ./runtests.py forms_tests\nIf the tests ran correctly, you should see one failure corresponding to the test\nmethod we added. If all of the tests passed, then you’ll want to make sure that\nyou added the new test shown above to the appropriate folder and class.
\nNext we’ll be adding the functionality described in ticket #24788 to\nDjango.
\nNavigate to the django/django/forms/ folder and open the forms.py file.\nFind the BaseForm class on line 72 and add the prefix class attribute\nright after the field_order attribute:
class BaseForm(object):\n # This is the main implementation of all the Form logic. Note that this\n # class is different than Form. See the comments by the Form class for\n # more information. Any improvements to the form API should be made to\n # *this* class, not to the Form class.\n field_order = None\n prefix = None\nOnce you’re done modifying Django, we need to make sure that the tests we wrote\nearlier pass, so we can see whether the code we wrote above is working\ncorrectly. To run the tests in the forms_tests folder, cd into the\nDjango tests/ directory and run:
$ ./runtests.py forms_tests\nOops, good thing we wrote those tests! You should still see one failure with\nthe following exception:
\nAssertionError: None != 'foo'\nWe forgot to add the conditional statement in the __init__ method. Go ahead\nand change self.prefix = prefix that is now on line 87 of\ndjango/forms/forms.py, adding a conditional statement:
if prefix is not None:\n self.prefix = prefix\nRe-run the tests and everything should pass. If it doesn’t, make sure you\ncorrectly modified the BaseForm class as shown above and copied the new test\ncorrectly.
Once you’ve verified that your patch and your test are working correctly, it’s\na good idea to run the entire Django test suite just to verify that your change\nhasn’t introduced any bugs into other areas of Django. While successfully\npassing the entire test suite doesn’t guarantee your code is bug free, it does\nhelp identify many bugs and regressions that might otherwise go unnoticed.
\nTo run the entire Django test suite, cd into the Django tests/\ndirectory and run:
$ ./runtests.py\nAs long as you don’t see any failures, you’re good to go.
\nThis is a new feature, so it should be documented. Add the following section on\nline 1068 (at the end of the file) of django/docs/ref/forms/api.txt:
The prefix can also be specified on the form class::\n\n >>> class PersonForm(forms.Form):\n ... ...\n ... prefix = 'person'\n\n.. versionadded:: 1.9\n\n The ability to specify ``prefix`` on the form class was added.\nSince this new feature will be in an upcoming release it is also added to the\nrelease notes for Django 1.9, on line 164 under the “Forms” section in the file\ndocs/releases/1.9.txt:
* A form prefix can be specified inside a form class, not only when\n instantiating a form. See :ref:`form-prefix` for details.\nFor more information on writing documentation, including an explanation of what\nthe versionadded bit is all about, see\nWriting documentation. That page also includes\nan explanation of how to build a copy of the documentation locally, so you can\npreview the HTML that will be generated.
Now it’s time to go through all the changes made in our patch. To display the\ndifferences between your current copy of Django (with your changes) and the\nrevision that you initially checked out earlier in the tutorial:
\n$ git diff\nUse the arrow keys to move up and down.
\ndiff --git a/django/forms/forms.py b/django/forms/forms.py\nindex 509709f..d1370de 100644\n--- a/django/forms/forms.py\n+++ b/django/forms/forms.py\n@@ -75,6 +75,7 @@ class BaseForm(object):\n # information. Any improvements to the form API should be made to *this*\n # class, not to the Form class.\n field_order = None\n+ prefix = None\n\n def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,\n initial=None, error_class=ErrorList, label_suffix=None,\n@@ -83,7 +84,8 @@ class BaseForm(object):\n self.data = data or {}\n self.files = files or {}\n self.auto_id = auto_id\n- self.prefix = prefix\n+ if prefix is not None:\n+ self.prefix = prefix\n self.initial = initial or {}\n self.error_class = error_class\n # Translators: This is the default suffix added to form field labels\ndiff --git a/docs/ref/forms/api.txt b/docs/ref/forms/api.txt\nindex 3bc39cd..008170d 100644\n--- a/docs/ref/forms/api.txt\n+++ b/docs/ref/forms/api.txt\n@@ -1065,3 +1065,13 @@ You can put several Django forms inside one ``<form>`` tag. To give each\n >>> print(father.as_ul())\n <li><label for="id_father-first_name">First name:</label> <input type="text" name="father-first_name" id="id_father-first_name" /></li>\n <li><label for="id_father-last_name">Last name:</label> <input type="text" name="father-last_name" id="id_father-last_name" /></li>\n+\n+The prefix can also be specified on the form class::\n+\n+ >>> class PersonForm(forms.Form):\n+ ... ...\n+ ... prefix = 'person'\n+\n+.. versionadded:: 1.9\n+\n+ The ability to specify ``prefix`` on the form class was added.\ndiff --git a/docs/releases/1.9.txt b/docs/releases/1.9.txt\nindex 5b58f79..f9bb9de 100644\n--- a/docs/releases/1.9.txt\n+++ b/docs/releases/1.9.txt\n@@ -161,6 +161,9 @@ Forms\n :attr:`~django.forms.Form.field_order` attribute, the ``field_order``\n constructor argument , or the :meth:`~django.forms.Form.order_fields` method.\n\n+* A form prefix can be specified inside a form class, not only when\n+ instantiating a form. See :ref:`form-prefix` for details.\n+\n Generic Views\n ^^^^^^^^^^^^^\n\ndiff --git a/tests/forms_tests/tests/test_forms.py b/tests/forms_tests/tests/test_forms.py\nindex 690f205..e07fae2 100644\n--- a/tests/forms_tests/tests/test_forms.py\n+++ b/tests/forms_tests/tests/test_forms.py\n@@ -1671,6 +1671,18 @@ class FormsTestCase(SimpleTestCase):\n self.assertEqual(p.cleaned_data['last_name'], 'Lennon')\n self.assertEqual(p.cleaned_data['birthday'], datetime.date(1940, 10, 9))\n\n+ def test_class_prefix(self):\n+ # Prefix can be also specified at the class level.\n+ class Person(Form):\n+ first_name = CharField()\n+ prefix = 'foo'\n+\n+ p = Person()\n+ self.assertEqual(p.prefix, 'foo')\n+\n+ p = Person(prefix='bar')\n+ self.assertEqual(p.prefix, 'bar')\n+\n def test_forms_with_null_boolean(self):\n # NullBooleanField is a bit of a special case because its presentation (widget)\n # is different than its data. This is handled transparently, though.\nWhen you’re done previewing the patch, hit the q key to return to the\ncommand line. If the patch’s content looked okay, it’s time to commit the\nchanges.
To commit the changes:
\n$ git commit -a\nThis opens up a text editor to type the commit message. Follow the commit\nmessage guidelines and write a message like:
\nFixed #24788 -- Allowed Forms to specify a prefix at the class level.\nAfter committing the patch, send it to your fork on GitHub (substitute\n“ticket_24788” with the name of your branch if it’s different):
\n$ git push origin ticket_24788\nYou can create a pull request by visiting the Django GitHub page. You’ll see your branch under “Your\nrecently pushed branches”. Click “Compare & pull request” next to it.
\nPlease don’t do it for this tutorial, but on the next page that displays a\npreview of the patch, you would click “Create pull request”.
\nCongratulations, you’ve learned how to make a pull request to Django! Details\nof more advanced techniques you may need are in\nWorking with Git and GitHub.
\nNow you can put those skills to good use by helping to improve Django’s\ncodebase.
\nBefore you get too into writing patches for Django, there’s a little more\ninformation on contributing that you should probably take a look at:
\nYou should make sure to read Django’s documentation on\nclaiming tickets and submitting patches.\nIt covers Trac etiquette, how to claim tickets for yourself, expected\ncoding style for patches, and many other important details.
First time contributors should also read Django’s documentation\nfor first time contributors.\nIt has lots of good advice for those of us who are new to helping out\nwith Django.
After those, if you’re still hungry for more information about\ncontributing, you can always browse through the rest of\nDjango’s documentation on contributing.\nIt contains a ton of useful information and should be your first source\nfor answering any questions you might have.
Once you’ve looked through some of that information, you’ll be ready to go out\nand find a ticket of your own to write a patch for. Pay special attention to\ntickets with the “easy pickings” criterion. These tickets are often much\nsimpler in nature and are great for first time contributors. Once you’re\nfamiliar with contributing to Django, you can move on to writing patches for\nmore difficult and complicated tickets.
\nIf you just want to get started already (and nobody would blame you!), try\ntaking a look at the list of easy tickets that need patches and the\neasy tickets that have patches which need improvement. If you’re familiar\nwith writing tests, you can also look at the list of\neasy tickets that need tests. Just remember to follow the guidelines about\nclaiming tickets that were mentioned in the link to Django’s documentation on\nclaiming tickets and submitting patches.
\nAfter a ticket has a patch, it needs to be reviewed by a second set of eyes.\nAfter submitting a pull request, update the ticket metadata by setting the\nflags on the ticket to say “has patch”, “doesn’t need tests”, etc, so others\ncan find it for review. Contributing doesn’t necessarily always mean writing a\npatch from scratch. Reviewing existing patches is also a very helpful\ncontribution. See Triaging tickets for details.
\n