2006-05-02 09:31:56 +08:00
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|
|
"""
|
|
|
|
4. Many-to-one relationships
|
|
|
|
|
|
|
|
To define a many-to-one relationship, use ``ForeignKey()`` .
|
|
|
|
"""
|
|
|
|
|
|
|
|
from django.db import models
|
|
|
|
|
|
|
|
class Reporter(models.Model):
|
2007-08-05 13:14:46 +08:00
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|
first_name = models.CharField(max_length=30)
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|
|
last_name = models.CharField(max_length=30)
|
2006-05-02 09:31:56 +08:00
|
|
|
email = models.EmailField()
|
|
|
|
|
Merged Unicode branch into trunk (r4952:5608). This should be fully
backwards compatible for all practical purposes.
Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2007-07-04 20:11:04 +08:00
|
|
|
def __unicode__(self):
|
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|
|
return u"%s %s" % (self.first_name, self.last_name)
|
2006-05-02 09:31:56 +08:00
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|
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class Article(models.Model):
|
2007-08-05 13:14:46 +08:00
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|
headline = models.CharField(max_length=100)
|
2006-05-02 09:31:56 +08:00
|
|
|
pub_date = models.DateField()
|
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|
|
reporter = models.ForeignKey(Reporter)
|
|
|
|
|
Merged Unicode branch into trunk (r4952:5608). This should be fully
backwards compatible for all practical purposes.
Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2007-07-04 20:11:04 +08:00
|
|
|
def __unicode__(self):
|
2006-05-02 09:31:56 +08:00
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|
return self.headline
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class Meta:
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|
ordering = ('headline',)
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|
2006-08-27 21:59:47 +08:00
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|
__test__ = {'API_TESTS':"""
|
2006-05-02 09:31:56 +08:00
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|
# Create a few Reporters.
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|
|
>>> r = Reporter(first_name='John', last_name='Smith', email='john@example.com')
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|
>>> r.save()
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|
>>> r2 = Reporter(first_name='Paul', last_name='Jones', email='paul@example.com')
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|
>>> r2.save()
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|
|
|
|
# Create an Article.
|
|
|
|
>>> from datetime import datetime
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|
|
>>> a = Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter=r)
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|
>>> a.save()
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|
|
>>> a.reporter.id
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|
1
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|
>>> a.reporter
|
2006-06-04 08:23:51 +08:00
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|
|
<Reporter: John Smith>
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Article objects have access to their related Reporter objects.
|
|
|
|
>>> r = a.reporter
|
|
|
|
>>> r.first_name, r.last_name
|
Merged Unicode branch into trunk (r4952:5608). This should be fully
backwards compatible for all practical purposes.
Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2007-07-04 20:11:04 +08:00
|
|
|
(u'John', u'Smith')
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Create an Article via the Reporter object.
|
|
|
|
>>> new_article = r.article_set.create(headline="John's second story", pub_date=datetime(2005, 7, 29))
|
|
|
|
>>> new_article
|
2006-06-04 08:23:51 +08:00
|
|
|
<Article: John's second story>
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> new_article.reporter.id
|
|
|
|
1
|
|
|
|
|
|
|
|
# Create a new article, and add it to the article set.
|
|
|
|
>>> new_article2 = Article(headline="Paul's story", pub_date=datetime(2006, 1, 17))
|
|
|
|
>>> r.article_set.add(new_article2)
|
|
|
|
>>> new_article2.reporter.id
|
|
|
|
1
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Add the same article to a different article set - check that it moves.
|
|
|
|
>>> r2.article_set.add(new_article2)
|
|
|
|
>>> new_article2.reporter.id
|
|
|
|
2
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> r2.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: Paul's story>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Assign the article to the reporter directly using the descriptor
|
|
|
|
>>> new_article2.reporter = r
|
|
|
|
>>> new_article2.save()
|
|
|
|
>>> new_article2.reporter
|
2006-06-04 08:23:51 +08:00
|
|
|
<Reporter: John Smith>
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> new_article2.reporter.id
|
|
|
|
1
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> r2.article_set.all()
|
|
|
|
[]
|
|
|
|
|
|
|
|
# Set the article back again using set descriptor.
|
|
|
|
>>> r2.article_set = [new_article, new_article2]
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> r2.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: Paul's story>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
2006-06-04 08:23:51 +08:00
|
|
|
# Funny case - assignment notation can only go so far; because the
|
2006-05-02 09:31:56 +08:00
|
|
|
# ForeignKey cannot be null, existing members of the set must remain
|
|
|
|
>>> r.article_set = [new_article]
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> r2.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: Paul's story>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Reporter cannot be null - there should not be a clear or remove method
|
|
|
|
>>> hasattr(r2.article_set, 'remove')
|
|
|
|
False
|
|
|
|
>>> hasattr(r2.article_set, 'clear')
|
|
|
|
False
|
|
|
|
|
|
|
|
# Reporter objects have access to their related Article objects.
|
|
|
|
>>> r.article_set.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
>>> r.article_set.filter(headline__startswith='This')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
>>> r.article_set.count()
|
|
|
|
2
|
|
|
|
|
|
|
|
>>> r2.article_set.count()
|
|
|
|
1
|
|
|
|
|
|
|
|
# Get articles by id
|
|
|
|
>>> Article.objects.filter(id__exact=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Article.objects.filter(pk=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Query on an article property
|
|
|
|
>>> Article.objects.filter(headline__startswith='This')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# The API automatically follows relationships as far as you need.
|
|
|
|
# Use double underscores to separate relationships.
|
|
|
|
# This works as many levels deep as you want. There's no limit.
|
|
|
|
# Find all Articles for any Reporter whose first name is "John".
|
|
|
|
>>> Article.objects.filter(reporter__first_name__exact='John')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
2006-07-01 11:14:33 +08:00
|
|
|
# Check that implied __exact also works
|
|
|
|
>>> Article.objects.filter(reporter__first_name='John')
|
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
|
|
|
|
2006-05-02 09:31:56 +08:00
|
|
|
# Query twice over the related field.
|
|
|
|
>>> Article.objects.filter(reporter__first_name__exact='John', reporter__last_name__exact='Smith')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# The underlying query only makes one join when a related table is referenced twice.
|
|
|
|
>>> query = Article.objects.filter(reporter__first_name__exact='John', reporter__last_name__exact='Smith')
|
|
|
|
>>> null, sql, null = query._get_sql_clause()
|
|
|
|
>>> sql.count('INNER JOIN')
|
|
|
|
1
|
|
|
|
|
|
|
|
# The automatically joined table has a predictable name.
|
|
|
|
>>> Article.objects.filter(reporter__first_name__exact='John').extra(where=["many_to_one_article__reporter.last_name='Smith'"])
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
Merged Unicode branch into trunk (r4952:5608). This should be fully
backwards compatible for all practical purposes.
Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2007-07-04 20:11:04 +08:00
|
|
|
# And should work fine with the unicode that comes out of
|
|
|
|
# newforms.Form.cleaned_data
|
|
|
|
>>> Article.objects.filter(reporter__first_name__exact='John').extra(where=["many_to_one_article__reporter.last_name='%s'" % u'Smith'])
|
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
|
|
|
|
2006-05-02 09:31:56 +08:00
|
|
|
# Find all Articles for the Reporter whose ID is 1.
|
Merged Unicode branch into trunk (r4952:5608). This should be fully
backwards compatible for all practical purposes.
Fixed #2391, #2489, #2996, #3322, #3344, #3370, #3406, #3432, #3454, #3492, #3582, #3690, #3878, #3891, #3937, #4039, #4141, #4227, #4286, #4291, #4300, #4452, #4702
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5609 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2007-07-04 20:11:04 +08:00
|
|
|
# Use direct ID check, pk check, and object comparison
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Article.objects.filter(reporter__id__exact=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Article.objects.filter(reporter__pk=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
2006-07-01 09:14:41 +08:00
|
|
|
>>> Article.objects.filter(reporter=1)
|
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
|
|
|
>>> Article.objects.filter(reporter=r)
|
|
|
|
[<Article: John's second story>, <Article: This is a test>]
|
|
|
|
|
|
|
|
>>> Article.objects.filter(reporter__in=[1,2]).distinct()
|
|
|
|
[<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]
|
|
|
|
>>> Article.objects.filter(reporter__in=[r,r2]).distinct()
|
|
|
|
[<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# You need two underscores between "reporter" and "id" -- not one.
|
|
|
|
>>> Article.objects.filter(reporter_id__exact=1)
|
|
|
|
Traceback (most recent call last):
|
|
|
|
...
|
2007-05-06 12:12:08 +08:00
|
|
|
TypeError: Cannot resolve keyword 'reporter_id' into field. Choices are: id, headline, pub_date, reporter
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# You need to specify a comparison clause
|
|
|
|
>>> Article.objects.filter(reporter_id=1)
|
|
|
|
Traceback (most recent call last):
|
|
|
|
...
|
2007-05-06 12:12:08 +08:00
|
|
|
TypeError: Cannot resolve keyword 'reporter_id' into field. Choices are: id, headline, pub_date, reporter
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# You can also instantiate an Article by passing
|
|
|
|
# the Reporter's ID instead of a Reporter object.
|
|
|
|
>>> a3 = Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter_id=r.id)
|
|
|
|
>>> a3.save()
|
|
|
|
>>> a3.reporter.id
|
|
|
|
1
|
|
|
|
>>> a3.reporter
|
2006-06-04 08:23:51 +08:00
|
|
|
<Reporter: John Smith>
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Similarly, the reporter ID can be a string.
|
|
|
|
>>> a4 = Article(id=None, headline="This is a test", pub_date=datetime(2005, 7, 27), reporter_id="1")
|
|
|
|
>>> a4.save()
|
|
|
|
>>> a4.reporter
|
2006-06-04 08:23:51 +08:00
|
|
|
<Reporter: John Smith>
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Reporters can be queried
|
|
|
|
>>> Reporter.objects.filter(id__exact=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(pk=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(first_name__startswith='John')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Reporters can query in opposite direction of ForeignKey definition
|
|
|
|
>>> Reporter.objects.filter(article__id__exact=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(article__pk=1)
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-07-01 09:14:41 +08:00
|
|
|
>>> Reporter.objects.filter(article=1)
|
|
|
|
[<Reporter: John Smith>]
|
|
|
|
>>> Reporter.objects.filter(article=a)
|
|
|
|
[<Reporter: John Smith>]
|
|
|
|
|
|
|
|
>>> Reporter.objects.filter(article__in=[1,4]).distinct()
|
|
|
|
[<Reporter: John Smith>]
|
|
|
|
>>> Reporter.objects.filter(article__in=[1,a3]).distinct()
|
|
|
|
[<Reporter: John Smith>]
|
|
|
|
>>> Reporter.objects.filter(article__in=[a,a3]).distinct()
|
|
|
|
[<Reporter: John Smith>]
|
|
|
|
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(article__headline__startswith='This')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>, <Reporter: John Smith>, <Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(article__headline__startswith='This').distinct()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
2006-05-15 07:49:29 +08:00
|
|
|
# Counting in the opposite direction works in conjunction with distinct()
|
|
|
|
>>> Reporter.objects.filter(article__headline__startswith='This').count()
|
|
|
|
3
|
|
|
|
>>> Reporter.objects.filter(article__headline__startswith='This').distinct().count()
|
|
|
|
1
|
|
|
|
|
2006-05-02 09:31:56 +08:00
|
|
|
# Queries can go round in circles.
|
|
|
|
>>> Reporter.objects.filter(article__reporter__first_name__startswith='John')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>, <Reporter: John Smith>, <Reporter: John Smith>, <Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.filter(article__reporter__first_name__startswith='John').distinct()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-07-01 09:14:41 +08:00
|
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>>> Reporter.objects.filter(article__reporter__exact=r).distinct()
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[<Reporter: John Smith>]
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2006-05-02 09:31:56 +08:00
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2006-07-01 11:14:33 +08:00
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# Check that implied __exact also works
|
|
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>>> Reporter.objects.filter(article__reporter=r).distinct()
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|
|
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[<Reporter: John Smith>]
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|
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2006-05-02 09:31:56 +08:00
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# If you delete a reporter, his articles will be deleted.
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|
|
|
>>> Article.objects.all()
|
2006-06-04 08:23:51 +08:00
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[<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>, <Article: This is a test>, <Article: This is a test>]
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2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.order_by('first_name')
|
2006-06-04 08:23:51 +08:00
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|
|
[<Reporter: John Smith>, <Reporter: Paul Jones>]
|
2006-05-02 09:31:56 +08:00
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|
|
>>> r2.delete()
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|
|
|
>>> Article.objects.all()
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Article: John's second story>, <Article: This is a test>, <Article: This is a test>, <Article: This is a test>]
|
2006-05-02 09:31:56 +08:00
|
|
|
>>> Reporter.objects.order_by('first_name')
|
2006-06-04 08:23:51 +08:00
|
|
|
[<Reporter: John Smith>]
|
2006-05-02 09:31:56 +08:00
|
|
|
|
|
|
|
# Deletes using a join in the query
|
|
|
|
>>> Reporter.objects.filter(article__headline__startswith='This').delete()
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|
|
>>> Reporter.objects.all()
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|
|
|
[]
|
|
|
|
>>> Article.objects.all()
|
|
|
|
[]
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|
|
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|
2006-08-27 21:59:47 +08:00
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|
"""}
|