Django views/filters

Question

I have just completed the Django tutorials, and while excited about learning more, I am by no means proficient. I guess you could say that I don't know enough to be dangerous at this point.

Let's say that I have a database of music. I have an Artist model, an Album model, a Genre model, and a Song model. What I would like to be able to do is display albums (or even artists) based on given filters; so my front-end would display a list of albums and provide a means to filter the list. A "Jazz" link, for instance, would only display Jazz albums. Simple enough.

I can think of a couple ways to accomplish this, but I would like to start out on the right foot...to begin forming "best practice" Django methods. One way I can think of would be to write views...such that /albums/jazz would only display jazz. Another way would be to write model-level methods that filter the albums. Here I get a little fuzzy on how I would actually implement such a filter, however.

Will someone please give me broad overview of how this task is best accomplished?

Joseph Victor Zammit · Accepted Answer · 2013-11-01 17:26:46Z

2

Assuming you know how to structure an app within a project (i.e. what the tutorial teaches) you can work along this example with example models.py, urls.py and views.py for your sample app myapp.

Example models.py:

class Genre(models.Model):
    name = models.CharField(unique=True) # set name to be unique
    ...

class Album(models.Model):
    genre = models.ForeignKey(Genre)
    ...

Example urls.py:

urlpatterns = patterns('',
    ...
    url(
        r'^albums/(?P<genre>[-\w]+)/$',
        ListAlbumsByGenreView.as_view(), name='list_albums_by_genre_view'
    ),
    ...
)

Note the genre parameter as the only argument in the URL pattern.

Example views.py using ListView:

from django.shortcuts import get_object_or_404
from django.views.generic.list import ListView

from myapp.models import Album, Genre

class ListAlbumsByGenreView(ListView):

    model = Album

    def get_context_data(self, **kwargs):
        context = super(ListAlbumsByGenreView, self).get_context_data(**kwargs)
        # fetch the genre; if genre not found, an HTTP 404 is returned
        genre = get_object_or_404(Genre, name=kwargs['genre'])
        # filter the albums by genre
        context['albums'] = Album.objects.filter(genre=genre)
        return context

The above ListView puts albums in your HTML template's context; this contains the list of albums filtered by genre.

The individually imported functions used above are all beautifully documented in the Django docs.

edited Nov 1, 2013 at 17:26

answered Nov 1, 2013 at 17:20

Joseph Victor Zammit

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2 Comments

user2945742 Over a year ago

Thank you very much. The only line I am having trouble understanding is: 'context = super(ListAlbumsByGenreView, self).get_context_data(**kwargs)'

Joseph Victor Zammit Over a year ago

get_context_data is an inherited method of ListView class; you have to call its super parent method so that you initiate the context with any context that the parent function returns. For example, if the ListView sets an page_no in the context, this call ensures this actually happens. Note that this is just an example. In this case I did it simply to follow best practices (and you should do that as well).

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