This is a work in progress, answering questions that do indeed get asked frequently on the [irc://irc.freenode.net/django Django IRC channel] (#django on irc.freenode.net). Feel free to contribute, but try to keep it clear and concise. Please don't editorialize. There's also a helpful [http://www.djangoproject.com/documentation/faq/ official FAQ]. [[TOC]] = General Tips = * When asking for help in the channel, '''be as specific as possible''' in your request. "It doesn't work" is not sufficiently specific! [http://code.djangoproject.com/wiki/IrcFAQ#MoreInformationPlease (More advice on this)] * General problem-'''solving''' advice: Test all the things you think are true until you find the one that isn't. * Showing actual code is useful. For code longer than a line or two, use the pastebin: http://dpaste.com/ * Django has very good [http://www.djangoproject.com/documentation/ documentation]. Make sure you've checked it! * Try [http://code.djangoproject.com/search?q=&wiki=on&ticket=on searching in Trac]. * Don't ask to ask, just ask! = Python questions = == How do I learn Python if I'm new to programming? == #LearnPython1 * http://www.ibiblio.org/obp/thinkCSpy/ * http://wiki.python.org/moin/BeginnersGuide/NonProgrammers == How do I learn Python if I'm '''not''' new to programming? == #LearnPython2 * http://docs.python.org/tut/tut.html * http://www.diveintopython.org/ * http://wiki.python.org/moin/BeginnersGuide/Programmers == Are there any books on Python? == #PythonBooks Yes. http://wiki.python.org/moin/PythonBooks == What's this about Python Path? Django is complaning it can't import stuff. == #PythonPath This is an important concept to understand in order to use Python/Django happily. [http://docs.python.org/tut/node8.html#SECTION008120000000000000000 The official Python tutorial explains it pretty well.] = Installing and Deploying Django = #InstallAndDeploy == Which version should I use, the 0.96 release or the Subversion checkout? == #WhichVersion The 0.96 release is well-tested and stable, and is best for production deployments. Tracking the development version of Django through a Subversion checkout can be nice if there's a new feature you really want, but does require you to pay more attention to what's going on in Django development -- if a backwards-incompatible change is introduced, you'll need to be watching the development timeline to notice it and change your code to suit, where sticking to official releases means that you get a list of any changes you need to make in the release notes. All backwards incompatible changes are (or should be) also recorded on the BackwardsIncompatibleChanges wiki page. Let us know (file a ticket) if you notice any genuine backwards incompatibilities that are missing. There will be several backwards-incompatible changes before the next release of Django (for example, the workings of the admin app will be changing), so it's officially recommended that production deployments stick to the 0.96 release until the next release is ready. == When will the next release be out? -or- When will X branch be done? == #AreWeThereYet "When it's done" is the short answer. Fixed release dates are rarely set, but searching or browsing the developer list (http://groups.google.com/group/django-developers/) can be informative. If you always want to run with the bleeding-edge, just use the SVN trunk rather than the last release (it's kept stable and is updated nearly every day). == I'm trying to install Django on Windows and something is weird. == #Windows Have you looked here? http://code.djangoproject.com/wiki/WindowsInstall == What should I use for development -- the built-in server, mod_python, FastCGI? == #WhichServer It's generally easiest to use the [http://www.djangoproject.com/documentation/django-admin/#runserver-optional-port-number-or-ipaddr-port built-in development server] for development, since it automatically reloads your Python source files when it detects changes. Apache needs to be restarted to see changes to your source files (unless you set {{{MaxRequestsPerChild 1}}}, which you should do with caution since it is not suitable for production). Some prefer to replicate the production environment as closely as possible, meaning that if their deployed project uses mod_python then their development server does as well. == What database should I use? == #WhichDB For development, most people find SQLite to be fastest and simplest to run with -- just make sure the database file and its directory are writeable by the owner of the web server process. For production, PostgreSQL and MySQL are the most thoroughly-tested of the databases Django supports, but it's best to choose based on the needs of your applications; for example, applications which do very little writing of data to the DB will enjoy the speed of SQLite, but applications which involve many complex queries or which require robust concurrent-write features like transaction isolation will probably want to look at Postgres or MySQL (and, of course, MySQL is often handy simply because many shared hosting providers have it set up by default). = Learning Django = #Learning == Should I read the documentation on the djangoproject.com website, or djangobook.com? == #WhichDocs Start with the [http://www.djangoproject.com/documentation/ documentation] here, and then have a look at the book if you're interested; the documentation on djangoproject.com includes the official tutorial, and a number of comprehensive references which aren't currently available in the book. == What's the difference between {{{null=True}}} and {{{blank=True}}} in models? == #NullVsBlank `null=True` means that the database will accept a `NULL` value for that field; `blank=True` means that Django's validation system won't complain about a missing value. If you use `blank=True` but ''not'' `null=True` you will need to have your code fill in a value before storage in the database -- specifying a default on a field, or putting something in the model's `save` method to generate a value are two good ways to handle this, and can be extremely useful when you want to calculate one field's value based on others. == Which runs faster, X or Y? == #WhichIsFaster This is a tempting question to ask in hopes of getting a quick answer on the "best" way to do something. Unfortunately, the answer is generally "profile your app and see". Performance tuning always starts with a baseline. If you haven't measured current performance to get a baseline, you aren't in a position to do much with the answer to the question anyway. You can learn more about Python's handy profiling tools in the [http://docs.python.org/lib/profile.html Python documentation]. = How to do Stuff = #HowTo == How do I create a subclass of an existing model? == #ModelInheritance Model inheritance (aka model subclassing) is available in Django trunk as of r7477. If you're using it, make sure you've [http://www.djangoproject.com/documentation/model-api/#model-inheritance read the documentation] and understand the difference between '''abstract base class''' and '''multi-table''' inheritance options. The latter can be confusing to newcomers because an instance of a parent class will also contain, on an attribute named after a child class, that same object represented as an instance of the child class. Got that? An established mechanism for adding additional information to Django `User` objects without subclassing is known as "profiles"; you can [http://www.djangobook.com/en/1.0/chapter12/#s-profiles read about it in the Definitive Guide]. For an important alternatve viewpoint on model subclassing, see: http://www.b-list.org/weblog/2007/02/20/about-model-subclassing == I think Ajax is awesome! How do I do Ajax with Django? == #Ajax Choose your favorite excellent Javascript library and go to it. Django provides serializers to JSON and XML, which you can read about in the documentation: http://www.djangoproject.com/documentation/serialization/ Also see this helpful article from James Bennett (with bonus anti-Javascript-helpers rant!): http://www.b-list.org/weblog/2006/07/02/django-and-ajax == How do I customise the admin interface so all logged-in users can use it without screwing up anything? == #AllUsersAdmin The admin interface is designed for use by trusted site staff, not by any user -- if you don't trust a user with the level of access the admin application provides, you'll need to provide non-admin views for the actions you'd like to allow them to take. == How do I make extensive changes in the admin interface? == #ExtensiveChangesAdmin At the moment it's probably best not to; the admin app is fairly specialized and doesn't have a lot of places to customize behavior, so you'll usually end up writing less code by just rolling your own set of views. The [http://code.djangoproject.com/wiki/NewformsAdminBranch newforms-admin branch], however, is significantly chanaging the admin app's interfaces to make customization much simpler and more flexible. For less extensive changes, also see the documentation in [http://www.djangobook.com/en/1.0/chapter17/ The Definitive Guide to Django]. == I want to have some code run when the server/application starts. How do I do that? == #ServerStartup Both mod_python and FastCGI are structured in such a way that there's no such thing as "application startup" or "server startup"; the best solution is to place your "startup" code somewhere that's guaranteed to be imported early on in the request/response cycle (the `__init__.py` file of your project, or of a specific application you're using, can be a good place, because Python will execute code found there the first time it has to import the module; just be aware that referencing the same module in different ways, say by doing `from myproject.myapp import foo` in one place, and `from myapp import foo` in another, will cause that code to be executed once for each different way you import it). == Do I have to hard-code my media URL in all my templates for CSS, images and Javascript? == #MediaURL No; you can use {{ MEDIA_URL }}. If you're using the development version of django and generic views, you can use {{ MEDIA_URL }} without changing anything. If you're using the development version and render_to_response(), you'll have to include RequestContext, as described here: http://www.djangoproject.com/documentation/templates_python/#subclassing-context-requestcontext If you're using 0.96, you can get the same functionality by creating a template context processor, as described: http://www.b-list.org/weblog/2006/jun/14/django-tips-template-context-processors/ == How do I use Django in a shell script? == #Shell http://www.b-list.org/weblog/2007/sep/22/standalone-django-scripts/ == Can I use the Date/Time picker !JavaScript from the Admin in my own app? == #DatePicker Short answer: No. Long answer: It is possible, but requires reusing the Admin JS and CSS, and is more trouble than it is worth. Most !JavaScript frameworks (such as [http://developer.yahoo.com/yui/ YUI], [http://dojotoolkit.org/ Dojo], [http://jquery.com/ jQuery], and [http://www.prototypejs.org/ Prototype]) provide similar functionality, either out of the box or through plugins. Additionally, there are many !JavaScript snippets available across the Web. == I want to repeat a bit of dynamic information (eg from a database) on many views. Do I have to change every view? == No, you can use an [http://www.djangoproject.com/documentation/templates_python/#inclusion-tags inclusion tag]. == If I change my model, will {{{manage.py syncdb}}} update my database table? == #ModelChanges No, you'll need to manually change your database table. If you use `manage.py sqlall` on your app to produce a SQL file before editing your models, you can run it again afterwards and use the difference between the two to see what you need to change in the database. = Troubleshooting = == "It doesn't work!" or "I got an error!" == #MoreInformationPlease If you want good help you'll need to give a little more information. Keep in mind that we probably know little if anything about your project, your level of experience with Python and Django, etc. Did it work before? Or is this something you're trying for the first time? Does it raise an error? Die silently? Give unexpected output? If you want help with an error, try to give us 1) the code that produced the error and 2) the error traceback itself. When asking for help, make sure you describe 1) what you did, 2) what you expected to happen, and 3) what actually happened. [http://dpaste.com/ Pasting] your code is often helpful. Don't forget to set the syntax when you paste so that the proper colorizing is applied -- that makes it easier for us to read your stuff. The Django debug page has a handy button for automatically sharing traceback code. == I'm using the development version (via Subversion) and when I ran "svn up" a bunch of stuff broke! == #SvnUp Don't use the development version of Django unless you also follow the BackwardsIncompatibleChanges and possibly the [http://code.djangoproject.com/timeline timeline] as well. That way you can see what has changed *before* you update. That way, changes like [http://code.djangoproject.com/wiki/BackwardsIncompatibleChanges#Auto-escapingintemplates auto-escaping of HTML in templates] won't catch you by surprise. Also, when reading the documentation, keep a special eye out for the "New In Development Version" sections. == The admin is working, but it can't find the Javascript and CSS and image files. == #AdminFiles If you're running the development server, read this: http://www.djangoproject.com/documentation/static_files/ If you're running Apache, read this: http://www.djangoproject.com/documentation/modpython/#serving-media-files == Why isn't my template tag or filter working? == #TemplateTagsAndFilters Of course, you've read the [http://www.djangoproject.com/documentation/templates_python/#extending-the-template-system documentation], right? Here's a brief list of things to check first before asking: * your filter/tag should be in a file named something like `[yourfilterlibraryname].py` (e.g. if it was `myfilter.py`, you'll use `{% load myfilter %}` in the template) * that file exists in a directory named `templatetags` and this directory is sitting inside of an ''app'' directory (e.g. `.../projectdir/appdir/templatetags`) * an empty file named `__init__.py` also exists in the `templatetags` directory (this makes the directory into a python module which can be imported) * in your project `settings.py`, the application where the `templatetags` directory is contained is in `INSTALLED_APPS` * each filter or tag in your library is decorated correctly (see docs) * neither your library nor anything it imports raises any exceptions (for example, if your library tries to import something that's not installed, and so raises an `ImportError`, that will prevent Django from seeing it) * restart the webserver (yes, even if you're using runserver) == I have a `DateField` or `DateTimeField` with a default value of `now()`, but it's not working! == What you've probably done is something like this: {{{ some_date_field = models.DateTimeField(default=datetime.datetime.now()) }}} When you do that you're immediately calling `datetime.datetime.now` and passing its return value -- ''at the moment the class is defined'' -- to be the default, which means it will not change during the life of a server process. What you want to do instead is this: {{{ some_date_field = models.DateTimeField(default=datetime.datetime.now) }}} Note that there are no parentheses on `datetime.datetime.now` in this version, so you're passing ''the function itself'' to be the default. When Django receives a function as a default value for a model field, it will call the function each time a new object is saved, and that will correctly generate the current date/time for each object. == I'm trying to use {{{__str__()}}} or {{{__unicode__()}}} on my model, but it's not working == #StrVsUnicode It's likely that you're using {{{__str__()}}} with the development version of Django, or {{{__unicode__()}}} with a release version. After the release of 0.96, Django's internals became fully Unicode aware. As a result, model classes that used to use {{{__str__()}}} to provide string versions of themselves need to be updated to use {{{__unicode__()}}} to work with the development version of Django. However, users of a Django release still need to use {{{__str__()}}}. More information on exactly what changed regarding Unicode in Django is available on the UnicodeBranch page. = Resources, Tools, and Code = #Resources == What editor is best for Django? == #WhichEditor [wiki:UsingVimWithDjango Vim]. No, wait, [wiki:Emacs Emacs]. A lot of people seem to like TextMate, too. The best editor is the editor ''you'' prefer. == Is there a free CMS available for Django? == #CMS At this point there is nothing well-established (like Plone, for instance). In practice, people mean so many different things by "CMS" that it may be hard to get a straight answer. This question is often asked by newcomers; one recommendation is to learn a bit of Django and see just how easy it is to make a site that does what you want. If you're in a big rush, there's always Ellington: http://www.ellingtoncms.com/ == Where can I find example code? == #ShowMeTheCode * http://djangosnippets.org/ * http://code.djangoproject.com/browser/djangoproject.com/django_website * http://www.djangosites.org/with-source/ * http://djangoplugables.com/ * http://code.google.com/hosting/search?q=label:django * http://github.com/search?q=django = IRC and djangoproject.com Miscellany = #Misc == The ticket tracker thinks I'm a spammer! == #TracTrouble You need to register: http://www.djangoproject.com/accounts/register/ == Is there a channel bot? == #DjangoBot Yes, it's very handy -- see DjangoBot for more.