[soc2010/query-refactor] MongoDB backend can now update saved objects.

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2010/query-refactor@13340 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/mongodb/base.py

@@ -9,6 +9,7 @@ from django.utils.importlib import import_module
 
 class DatabaseFeatures(object):
     interprets_empty_strings_as_nulls = False
+    typed_columns = False
 
 
 class DatabaseOperations(object):

django/contrib/mongodb/compiler.py

@@ -5,6 +5,54 @@ class SQLCompiler(object):
         self.connection = connection
         self.using = using
     
+    def get_filters(self, where):
+        assert where.connector == "AND"
+        assert not where.negated
+        filters = {}
+        for child in where.children:
+            if isinstance(child, self.query.where_class):
+                # TODO: probably needs to check for dupe keys
+                filters.update(self.get_filters(child))
+            else:
+                field, val = self.make_atom(*child)
+                filters[field] = val
+        return filters
+    
+    def make_atom(self, lhs, lookup_type, value_annotation, params_or_value):
+        assert lookup_type == "exact"
+        if hasattr(lhs, "process"):
+            lhs, params = lhs.process(lookup_type, params_or_value, self.connection)
+        else:
+            params = Field().get_db_prep_lookup(lookup_type, params_or_value, 
+                connection=self.connection, prepared=True)
+        assert isinstance(lhs, (list, tuple))
+        table, column, _ = lhs
+        assert table == self.query.model._meta.db_table
+        if column == self.query.model._meta.pk.column:
+            column = "_id"
+        return column, params[0]
+    
+    def build_query(self):
+        assert not self.query.aggregates
+        assert len(self.query.alias_map) == 1
+        assert self.query.default_cols
+        assert not self.query.distinct
+        assert not self.query.extra
+        assert not self.query.having
+        assert self.query.high_mark is None
+        assert not self.query.order_by
+        
+        filters = self.get_filters(self.query.where)
+        return self.connection.db[self.query.model._meta.db_table].find(filters)
+    
+    def has_results(self):
+        try:
+            self.build_query()[0]
+        except IndexError:
+            return False
+        else:
+            return True
+
 
 class SQLInsertCompiler(SQLCompiler):
     def insert(self, return_id=False):

django/db/models/fields/__init__.py

@@ -215,6 +215,8 @@ class Field(object):
         # mapped to one of the built-in Django field types. In this case, you
         # can implement db_type() instead of get_internal_type() to specify
         # exactly which wacky database column type you want to use.
+        if not getattr(connection.features, "typed_columns", True):
+            return None
         data = DictWrapper(self.__dict__, connection.ops.quote_name, "qn_")
         try:
             return connection.creation.data_types[self.get_internal_type()] % data

tests/regressiontests/mongodb/tests.py

@@ -9,3 +9,12 @@ class MongoTestCase(TestCase):
         self.assertTrue(b.pk is not None)
         self.assertEqual(b.name, "Bruce Springsteen")
         self.assertTrue(b.good)
+    
+    def test_update(self):
+        l = Artist.objects.create(name="Lady Gaga", good=True)
+        self.assertTrue(l.pk is not None)
+        pk = l.pk
+        # Whoops, we screwed up.
+        l.good = False
+        l.save()
+        self.assertEqual(l.pk, pk)