"""

35. DB-API Shortcuts

get_object_or_404 is a shortcut function to be used in view functions for

performing a get() lookup and raising a Http404 exception if a DoesNotExist

exception was rasied during the get() call.

get_list_or_404 is a shortcut function to be used in view functions for

performing a filter() lookup and raising a Http404 exception if a DoesNotExist

exception was rasied during the filter() call.

"""

from django.db import models

from django.http import Http404

from django.shortcuts import get_object_or_404, get_list_or_404

class Author(models.Model):

    name = models.CharField(maxlength=50)

    def __str__(self):

        return self.name

class ArticleManager(models.Manager):

    def get_query_set(self):

        return super(ArticleManager, self).get_query_set().filter(authors__name__icontains='sir')

class Article(models.Model):

    authors = models.ManyToManyField(Author)

    title = models.CharField(maxlength=50)

    objects = models.Manager()

    by_a_sir = ArticleManager()

    def __str__(self):

        return self.title

__test__ = {'API_TESTS':"""

# Create some Authors.

>>> a = Author.objects.create(name="Brave Sir Robin")

>>> a.save()

>>> a2 = Author.objects.create(name="Patsy")

>>> a2.save()

# No Articles yet, so we should get a Http404 error.

>>> get_object_or_404(Article, title="Foo")

Traceback (most recent call last):

...

Http404: No Article matches the given query.

# Create an Article.

>>> article = Article.objects.create(title="Run away!")

>>> article.authors = [a, a2]

>>> article.save()

# get_object_or_404 can be passed a Model to query.

>>> get_object_or_404(Article, title__contains="Run")

<Article: Run away!>

# We can also use the the Article manager through an Author object.

>>> get_object_or_404(a.article_set, title__contains="Run")

<Article: Run away!>

# No articles containing "Camelot".  This should raise a Http404 error.

>>> get_object_or_404(a.article_set, title__contains="Camelot")

Traceback (most recent call last):

...

Http404: No Article matches the given query.

# Custom managers can be used too.

>>> get_object_or_404(Article.by_a_sir, title="Run away!")

<Article: Run away!>

# get_list_or_404 can be used to get lists of objects

>>> get_list_or_404(a.article_set, title__icontains='Run')

[<Article: Run away!>]

# Http404 is returned if the list is empty

>>> get_list_or_404(a.article_set, title__icontains='Shrubbery')

Traceback (most recent call last):

...

Http404: No Article matches the given query.

# Custom managers can be used too.

>>> get_list_or_404(Article.by_a_sir, title__icontains="Run")

[<Article: Run away!>]

"""}