Ticket #785: m2m_column_names.patch

django/db/models/fields/related.py

@@ -634 +634 @@
             raw_id_admin=kwargs.pop('raw_id_admin', False),
             symmetrical=kwargs.pop('symmetrical', True))
         self.db_table = kwargs.pop('db_table', None)
+        self.db_self_column = kwargs.pop('db_self_column', None)
+        self.db_related_column = kwargs.pop('db_related_column', None)
         if kwargs["rel"].raw_id_admin:
             kwargs.setdefault("validator_list", []).append(self.isValidIDList)
         Field.__init__(self, **kwargs)
@@ -663 +665 @@
 
     def _get_m2m_column_name(self, related):
         "Function that can be curried to provide the source column name for the m2m table"
+        if self.db_self_column:
+            return self.db_self_column
         # If this is an m2m relation to self, avoid the inevitable name clash
-        if related.model == related.parent_model:
+        elif related.model == related.parent_model:
             return 'from_' + related.model._meta.object_name.lower() + '_id'
         else:
             return related.model._meta.object_name.lower() + '_id'
 
     def _get_m2m_reverse_name(self, related):
         "Function that can be curried to provide the related column name for the m2m table"
+        if self.db_related_column:
+            return self.db_related_column
         # If this is an m2m relation to self, avoid the inevitable name clash
-        if related.model == related.parent_model:
+        elif related.model == related.parent_model:
             return 'to_' + related.parent_model._meta.object_name.lower() + '_id'
         else:
             return related.parent_model._meta.object_name.lower() + '_id'

docs/model-api.txt

@@ -893 +893 @@
                              data. If this is not provided, Django will assume a default
                              name based upon the names of the two tables being joined.
 
+    ``db_self_column''       The name of the column for storing primary key of this model
+                             in the table created for storing the many-to-many data. If
+                             this is not provided, Django will assume a default name
+                             based upon the name of the current model.
+
+    ``db_related_column``    The name of the column for storing primary key of the related
+                             model in the table created for storing the many-to-many data.
+                             If this is not provided, Django will assume a default name
+                             based upon the name of the related model.
+
     =======================  ============================================================
 
 One-to-one relationships

tests/modeltests/custom_columns/models.py

@@ -28 +28 @@
         db_table = 'my_author_table'
         ordering = ('last_name','first_name')
 
+class Category(models.Model):
+    name = models.CharField(maxlength=20)
+    class Meta:
+       ordering = ('name',)
+
+    def __str__(self):
+        return self.name
+
 class Article(models.Model):
     headline = models.CharField(maxlength=100)
     authors = models.ManyToManyField(Author, db_table='my_m2m_table')
+    categories = models.ManyToManyField(Category, db_self_column='m2m_article_id', db_related_column='m2m_category_id')
 
     def __str__(self):
         return self.headline
@@ -51 +60 @@
 >>> a2.save()
 
 # Create an article
->>> art = Article(headline='Django lets you build web apps easily')
->>> art.save()
->>> art.authors = [a, a2]
+>>> art1 = Article(headline='Django lets you build web apps easily')
+>>> art1.save()
+>>> art1.authors = [a, a2]
 
 # Although the table and column names on Author have been set to 
 # custom values, nothing about using the Author model has changed...
@@ -91 +100 @@
 # nothing about using the m2m relationship has changed...
 
 # Get all the authors for an article
->>> art.authors.all()
+>>> art1.authors.all()
 [<Author: Peter Jones>, <Author: John Smith>]
 
 # Get the articles for an author
@@ -99 +108 @@
 [<Article: Django lets you build web apps easily>]
 
 # Query the authors across the m2m relation
->>> art.authors.filter(last_name='Jones')
+>>> art1.authors.filter(last_name='Jones')
 [<Author: Peter Jones>]
 
+# Create some categories
+>>> c1 = Category(name='Python')
+>>> c1.save()
+>>> c2 = Category(name='Django')
+>>> c2.save()
+
+# Assign categories to models
+>>> art1.categories = [c1, c2]
+>>> art2 = Article(headline='Dive into Python')
+>>> art2.save()
+>>> art2.categories = [c1]
+
+# Verify that m2m operations are performed with custom column names on m2m
+# relation table
+
+>>> c1.article_set.all()
+[<Article: Dive into Python>, <Article: Django lets you build web apps easily>]
+
+>>> c2.article_set.all()
+[<Article: Django lets you build web apps easily>]
+
+>>> art1.categories.all()
+[<Category: Django>, <Category: Python>]
+
+>>> art2.categories.all()
+[<Category: Python>]
+
 """}