106 lines
2.9 KiB
Python
106 lines
2.9 KiB
Python
"""
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17. Custom column/table names
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If your database column name is different than your model attribute, use the
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``db_column`` parameter. Note that you'll use the field's name, not its column
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name, in API usage.
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If your database table name is different than your model name, use the
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``db_table`` Meta attribute. This has no effect on the API used to
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query the database.
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If you need to use a table name for a many-to-many relationship that differs
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from the default generated name, use the ``db_table`` parameter on the
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ManyToMany field. This has no effect on the API for querying the database.
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"""
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from django.db import models
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class Author(models.Model):
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first_name = models.CharField(maxlength=30, db_column='firstname')
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last_name = models.CharField(maxlength=30, db_column='last')
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def __str__(self):
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return '%s %s' % (self.first_name, self.last_name)
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class Meta:
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db_table = 'my_author_table'
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ordering = ('last_name','first_name')
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class Article(models.Model):
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headline = models.CharField(maxlength=100)
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authors = models.ManyToManyField(Author, db_table='my_m2m_table')
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def __str__(self):
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return self.headline
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class Meta:
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ordering = ('headline',)
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__test__ = {'API_TESTS':"""
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# Create a Author.
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>>> a = Author(first_name='John', last_name='Smith')
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>>> a.save()
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>>> a.id
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1
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# Create another author
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>>> a2 = Author(first_name='Peter', last_name='Jones')
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>>> a2.save()
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# Create an article
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>>> art = Article(headline='Django lets you build web apps easily')
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>>> art.save()
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>>> art.authors = [a, a2]
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# Although the table and column names on Author have been set to
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# custom values, nothing about using the Author model has changed...
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# Query the available authors
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>>> Author.objects.all()
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[<Author: Peter Jones>, <Author: John Smith>]
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>>> Author.objects.filter(first_name__exact='John')
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[<Author: John Smith>]
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>>> Author.objects.get(first_name__exact='John')
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<Author: John Smith>
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>>> Author.objects.filter(firstname__exact='John')
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Traceback (most recent call last):
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...
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TypeError: Cannot resolve keyword 'firstname' into field. Choices are: article, id, first_name, last_name
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>>> a = Author.objects.get(last_name__exact='Smith')
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>>> a.first_name
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'John'
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>>> a.last_name
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'Smith'
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>>> a.firstname
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Traceback (most recent call last):
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...
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AttributeError: 'Author' object has no attribute 'firstname'
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>>> a.last
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Traceback (most recent call last):
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...
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AttributeError: 'Author' object has no attribute 'last'
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# Although the Article table uses a custom m2m table,
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# nothing about using the m2m relationship has changed...
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# Get all the authors for an article
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>>> art.authors.all()
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[<Author: Peter Jones>, <Author: John Smith>]
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# Get the articles for an author
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>>> a.article_set.all()
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[<Article: Django lets you build web apps easily>]
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# Query the authors across the m2m relation
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>>> art.authors.filter(last_name='Jones')
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[<Author: Peter Jones>]
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"""}
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