Fixed #3098 -- Added db_table parameter to m2m fields, allowing the specification of a custom table name for the m2m table. Thanks, Wolfram Kriesing.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4429 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/related.py

@@ -629,6 +629,7 @@ class ManyToManyField(RelatedField, Field):
             limit_choices_to=kwargs.pop('limit_choices_to', None),
             raw_id_admin=kwargs.pop('raw_id_admin', False),
             symmetrical=kwargs.pop('symmetrical', True))
+        self.db_table = kwargs.pop('db_table', None)
         if kwargs["rel"].raw_id_admin:
             kwargs.setdefault("validator_list", []).append(self.isValidIDList)
         Field.__init__(self, **kwargs)
@@ -651,6 +652,9 @@ class ManyToManyField(RelatedField, Field):
 
     def _get_m2m_db_table(self, opts):
         "Function that can be curried to provide the m2m table name for this relation"
+        if self.db_table:
+            return self.db_table
+        else:
             return '%s_%s' % (opts.db_table, self.name)
 
     def _get_m2m_column_name(self, related):

docs/model-api.txt

@@ -875,6 +875,10 @@ the relationship should work. All are optional:
                              relationship, allowing ``ManyToMany`` relationships to be
                              non-symmetrical.
 			     
+    ``db_table``             The name of the table to create for storing the many-to-many 
+                             data. If this is not provided, Django will assume a default
+                             name based upon the names of the two tables being joined.
+
     =======================  ============================================================
 
 One-to-one relationships

tests/modeltests/custom_columns/models.py

@@ -1,53 +1,105 @@
 """
-17. Custom column names
+17. Custom column/table names
 
 If your database column name is different than your model attribute, use the
 ``db_column`` parameter. Note that you'll use the field's name, not its column
 name, in API usage.
+
+If your database table name is different than your model name, use the
+``db_table`` Meta attribute. This has no effect on the API used to 
+query the database.
+
+If you need to use a table name for a many-to-many relationship that differs 
+from the default generated name, use the ``db_table`` parameter on the 
+ManyToMany field. This has no effect on the API for querying the database.
+
 """
 
 from django.db import models
 
-class Person(models.Model):
+class Author(models.Model):
     first_name = models.CharField(maxlength=30, db_column='firstname')
     last_name = models.CharField(maxlength=30, db_column='last')
 
     def __str__(self):
         return '%s %s' % (self.first_name, self.last_name)
 
-__test__ = {'API_TESTS':"""
+    class Meta:
-# Create a Person.
+        db_table = 'my_author_table'
->>> p = Person(first_name='John', last_name='Smith')
+        ordering = ('last_name','first_name')
->>> p.save()
 
->>> p.id
+class Article(models.Model):
+    headline = models.CharField(maxlength=100)
+    authors = models.ManyToManyField(Author, db_table='my_m2m_table')
+
+    def __str__(self):
+        return self.headline
+
+    class Meta:
+        ordering = ('headline',)
+        
+__test__ = {'API_TESTS':"""
+# Create a Author.
+>>> a = Author(first_name='John', last_name='Smith')
+>>> a.save()
+
+>>> a.id
 1
 
->>> Person.objects.all()
+# Create another author
-[<Person: John Smith>]
+>>> a2 = Author(first_name='Peter', last_name='Jones')
+>>> a2.save()
 
->>> Person.objects.filter(first_name__exact='John')
+# Create an article
-[<Person: John Smith>]
+>>> art = Article(headline='Django lets you build web apps easily')
+>>> art.save()
+>>> art.authors = [a, a2]
 
->>> Person.objects.get(first_name__exact='John')
+# Although the table and column names on Author have been set to 
-<Person: John Smith>
+# custom values, nothing about using the Author model has changed...
 
->>> Person.objects.filter(firstname__exact='John')
+# Query the available authors
+>>> Author.objects.all()
+[<Author: Peter Jones>, <Author: John Smith>]
+
+>>> Author.objects.filter(first_name__exact='John')
+[<Author: John Smith>]
+
+>>> Author.objects.get(first_name__exact='John')
+<Author: John Smith>
+
+>>> Author.objects.filter(firstname__exact='John')
 Traceback (most recent call last):
     ...
 TypeError: Cannot resolve keyword 'firstname' into field
 
->>> p = Person.objects.get(last_name__exact='Smith')
+>>> a = Author.objects.get(last_name__exact='Smith')
->>> p.first_name
+>>> a.first_name
 'John'
->>> p.last_name
+>>> a.last_name
 'Smith'
->>> p.firstname
+>>> a.firstname
 Traceback (most recent call last):
     ...
-AttributeError: 'Person' object has no attribute 'firstname'
+AttributeError: 'Author' object has no attribute 'firstname'
->>> p.last
+>>> a.last
 Traceback (most recent call last):
     ...
-AttributeError: 'Person' object has no attribute 'last'
+AttributeError: 'Author' object has no attribute 'last'
+
+# Although the Article table uses a custom m2m table, 
+# nothing about using the m2m relationship has changed...
+
+# Get all the authors for an article
+>>> art.authors.all()
+[<Author: Peter Jones>, <Author: John Smith>]
+
+# Get the articles for an author
+>>> a.article_set.all()
+[<Article: Django lets you build web apps easily>]
+
+# Query the authors across the m2m relation
+>>> art.authors.filter(last_name='Jones')
+[<Author: Peter Jones>]
+
 """}