[soc2009/multidb] Fixed a bug with EmptyQuerySet.

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/multidb@11257 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/commands/createcachetable.py

@@ -2,6 +2,7 @@ from optparse import make_option
 
 from django.core.management.base import LabelCommand
 from django.db import connections, transaction, models, DEFAULT_DB_ALIAS
+from django.db.utils import call_with_connection
 
 class Command(LabelCommand):
     help = "Creates the table needed to use the SQL cache backend."
@@ -30,7 +31,7 @@ class Command(LabelCommand):
         index_output = []
         qn = connection.ops.quote_name
         for f in fields:
-            field_output = [qn(f.name), f.db_type(connection)]
+            field_output = [qn(f.name), call_with_connection(f.db_type, connection=connection)]
             field_output.append("%sNULL" % (not f.null and "NOT " or ""))
             if f.primary_key:
                 field_output.append("PRIMARY KEY")

django/db/backends/creation.py

@@ -8,6 +8,7 @@ except NameError:
 
 from django.conf import settings
 from django.core.management import call_command
+from django.db.utils import call_with_connection
 
 # The prefix to put on the default database name when creating
 # the test database.
@@ -47,7 +48,7 @@ class BaseDatabaseCreation(object):
         pending_references = {}
         qn = self.connection.ops.quote_name
         for f in opts.local_fields:
-            col_type = f.db_type(self.connection)
+            col_type = call_with_connection(f.db_type, connection=self.connection)
             tablespace = f.db_tablespace or opts.db_tablespace
             if col_type is None:
                 # Skip ManyToManyFields, because they're not represented as

django/db/models/fields/related.py

@@ -5,6 +5,7 @@ from django.db.models.fields import AutoField, Field, IntegerField, PositiveInte
 from django.db.models.related import RelatedObject
 from django.db.models.query import QuerySet
 from django.db.models.query_utils import QueryWrapper
+from django.db.utils import call_with_connection
 from django.utils.encoding import smart_unicode
 from django.utils.translation import ugettext_lazy, string_concat, ungettext, ugettext as _
 from django.utils.functional import curry
@@ -772,7 +773,7 @@ class ForeignKey(RelatedField, Field):
                 isinstance(rel_field, (PositiveIntegerField,
                                        PositiveSmallIntegerField)))):
             return IntegerField().db_type(connection)
-        return rel_field.db_type(connection)
+        return call_with_connection(rel_field.db_type, connection=connection)
 
 class OneToOneField(ForeignKey):
     """

django/db/models/query.py

@@ -33,7 +33,12 @@ class QuerySet(object):
     """
     def __init__(self, model=None, query=None):
         self.model = model
-        using = model._meta.using or DEFAULT_DB_ALIAS
+        # EmptyQuerySet instantiates QuerySet with model as None
+        if model:
+            using = model._meta.using
+        else:
+            using = None
+        using = using or DEFAULT_DB_ALIAS
         connection = connections[using]
         self.query = query or sql.Query(self.model, connection)
         self._result_cache = None

django/db/models/sql/where.py

@@ -6,6 +6,7 @@ import datetime
 from django.utils import tree
 from django.db.models.fields import Field
 from django.db.models.query_utils import QueryWrapper
+from django.db.utils import call_with_connection
 from datastructures import EmptyResultSet, FullResultSet
 
 # Connection types
@@ -266,7 +267,7 @@ class Constraint(object):
         try:
             if self.field:
                 params = self.field.get_db_prep_lookup(lookup_type, value)
-                db_type = self.field.db_type(connection)
+                db_type = call_with_connection(self.field.db_type, connection=connection)
             else:
                 # This branch is used at times when we add a comparison to NULL
                 # (we don't really want to waste time looking up the associated

django/db/utils.py

@@ -1,3 +1,4 @@
+import inspect
 import os
 
 from django.conf import settings
@@ -31,6 +32,13 @@ def load_backend(backend_name):
             else:
                 raise # If there's some other error, this must be an error in Django itself.
 
+def call_with_connection(func, *args, **kwargs):
+    arg_names, varargs, varkwargs, defaults = inspect.getargspec(func)
+    if 'connection' not in arg_names and varkwargs is None:
+        del kwargs['connection']
+    return func(*args, **kwargs)
+
+
 class ConnectionHandler(object):
     def __init__(self, databases):
         self.databases = databases