108 lines
3.3 KiB
Python
108 lines
3.3 KiB
Python
"""
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35. DB-API Shortcuts
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get_object_or_404 is a shortcut function to be used in view functions for
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performing a get() lookup and raising a Http404 exception if a DoesNotExist
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exception was raised during the get() call.
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get_list_or_404 is a shortcut function to be used in view functions for
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performing a filter() lookup and raising a Http404 exception if a DoesNotExist
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exception was raised during the filter() call.
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"""
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from django.db import models
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from django.http import Http404
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from django.shortcuts import get_object_or_404, get_list_or_404
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class Author(models.Model):
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name = models.CharField(max_length=50)
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def __unicode__(self):
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return self.name
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class ArticleManager(models.Manager):
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def get_query_set(self):
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return super(ArticleManager, self).get_query_set().filter(authors__name__icontains='sir')
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class Article(models.Model):
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authors = models.ManyToManyField(Author)
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title = models.CharField(max_length=50)
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objects = models.Manager()
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by_a_sir = ArticleManager()
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def __unicode__(self):
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return self.title
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__test__ = {'API_TESTS':"""
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# Create some Authors.
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>>> a = Author.objects.create(name="Brave Sir Robin")
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>>> a.save()
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>>> a2 = Author.objects.create(name="Patsy")
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>>> a2.save()
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# No Articles yet, so we should get a Http404 error.
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>>> get_object_or_404(Article, title="Foo")
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Traceback (most recent call last):
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...
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Http404: No Article matches the given query.
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# Create an Article.
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>>> article = Article.objects.create(title="Run away!")
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>>> article.authors = [a, a2]
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>>> article.save()
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# get_object_or_404 can be passed a Model to query.
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>>> get_object_or_404(Article, title__contains="Run")
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<Article: Run away!>
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# We can also use the the Article manager through an Author object.
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>>> get_object_or_404(a.article_set, title__contains="Run")
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<Article: Run away!>
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# No articles containing "Camelot". This should raise a Http404 error.
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>>> get_object_or_404(a.article_set, title__contains="Camelot")
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Traceback (most recent call last):
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...
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Http404: No Article matches the given query.
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# Custom managers can be used too.
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>>> get_object_or_404(Article.by_a_sir, title="Run away!")
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<Article: Run away!>
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# QuerySets can be used too.
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>>> get_object_or_404(Article.objects.all(), title__contains="Run")
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<Article: Run away!>
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# Just as when using a get() lookup, you will get an error if more than one
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# object is returned.
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>>> get_object_or_404(Author.objects.all())
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Traceback (most recent call last):
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...
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MultipleObjectsReturned: get() returned more than one Author -- it returned ...! Lookup parameters were {}
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# Using an EmptyQuerySet raises a Http404 error.
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>>> get_object_or_404(Article.objects.none(), title__contains="Run")
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Traceback (most recent call last):
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...
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Http404: No Article matches the given query.
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# get_list_or_404 can be used to get lists of objects
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>>> get_list_or_404(a.article_set, title__icontains='Run')
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[<Article: Run away!>]
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# Http404 is returned if the list is empty.
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>>> get_list_or_404(a.article_set, title__icontains='Shrubbery')
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Traceback (most recent call last):
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...
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Http404: No Article matches the given query.
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# Custom managers can be used too.
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>>> get_list_or_404(Article.by_a_sir, title__icontains="Run")
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[<Article: Run away!>]
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# QuerySets can be used too.
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>>> get_list_or_404(Article.objects.all(), title__icontains="Run")
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[<Article: Run away!>]
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"""}
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