magic-removal: Fixed #1082 -- Added a 'supports_constraints' variable…

… for each database backend, and set SQLite's to False

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@1757 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management.py

@@ -117,18 +117,19 @@ def get_sql_create(app):
 
         # Take care of any ALTER TABLE statements to add constraints
         # after the fact.
-        if klass in pending_references:
-            for rel_class, f in pending_references[klass]:
-                rel_opts = rel_class._meta
-                r_table = rel_opts.db_table
-                r_col = f.column
-                table = opts.db_table
-                col = opts.get_field(f.rel.field_name).column
-                final_output.append('ALTER TABLE %s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s);' % \
-                    (backend.quote_name(r_table),
-                    backend.quote_name("%s_referencing_%s_%s" % (r_col, table, col)),
-                    backend.quote_name(r_col), backend.quote_name(table), backend.quote_name(col)))
-            del pending_references[klass]
+        if backend.supports_constraints:
+            if klass in pending_references:
+                for rel_class, f in pending_references[klass]:
+                    rel_opts = rel_class._meta
+                    r_table = rel_opts.db_table
+                    r_col = f.column
+                    table = opts.db_table
+                    col = opts.get_field(f.rel.field_name).column
+                    final_output.append('ALTER TABLE %s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s);' % \
+                        (backend.quote_name(r_table),
+                        backend.quote_name("%s_referencing_%s_%s" % (r_col, table, col)),
+                        backend.quote_name(r_col), backend.quote_name(table), backend.quote_name(col)))
+                del pending_references[klass]
 
         # Keep track of the fact that we've created the table for this model.
         models_output.add(klass)

django/db/backends/ado_mssql/base.py

@@ -76,6 +76,8 @@ def close(self):
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith('[') and name.endswith(']'):
         return name # Quoting once is enough.

django/db/backends/mysql/base.py

@@ -83,6 +83,8 @@ def close(self):
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith("`") and name.endswith("`"):
         return name # Quoting once is enough.

django/db/backends/postgresql/base.py

@@ -49,6 +49,8 @@ def close(self):
             self.connection.close()
             self.connection = None
 
+supports_constraints = True
+
 def quote_name(name):
     if name.startswith('"') and name.endswith('"'):
         return name # Quoting once is enough.

django/db/backends/sqlite3/base.py

@@ -70,6 +70,8 @@ def convert_query(self, query, num_params):
         # XXX this seems too simple to be correct... is this right?
         return query % tuple("?" * num_params)
 
+supports_constraints = False
+
 def quote_name(name):
     if name.startswith('"') and name.endswith('"'):
         return name # Quoting once is enough.