Merge branch 'dev/db-groupby' into dev/dbv0.2.0

1 files changed, 60 insertions, 0 deletions

diff --git a/db.py b/db.py
new file mode 100644
index 0000000..2d4d320
--- /dev/null
+++ b/db.py
@@ -0,0 +1,60 @@
+from django.db import connections
+from django.db.models import Manager
+from django.db.models.query import QuerySet
+from django.db.models.sql.compiler import SQLCompiler
+from django.db.models.sql.query import Query
+from django.db.models.sql.where import WhereNode
+
+
+class GroupedCompiler(SQLCompiler):
+    def get_group_by(self, select, order_by):
+        result = super(GroupedCompiler, self).get_group_by(select, order_by)
+        expressions = []
+        for expr in self.query.real_group_by:
+            ref = expr if hasattr(expr, "as_sql") else self.query.resolve_ref(expr)
+            sql, params = self.compile(ref)
+            result.append((sql, params))
+
+        return result
+
+
+class GroupedQuery(Query):
+    def __init__(self, model, where=WhereNode):
+        super(GroupedQuery, self).__init__(model, where)
+        self.real_group_by = []
+
+    def clone(self, klass=None, memo=None, **kwargs):
+        obj = super(GroupedQuery, self).clone(klass, memo, **kwargs)
+        obj.real_group_by = self.real_group_by[:]
+        return obj
+
+    def add_grouping(self, *grouping):
+        self.real_group_by.extend(grouping)
+
+    def clear_grouping(self):
+        self.real_group_by = []
+
+    def get_compiler(self, using=None, connection=None):
+        if using is None and connection is None:
+            raise ValueError("Need either using or connection")
+        if using:
+            connection = connections[using]
+        return GroupedCompiler(self, connection, using)
+
+
+class GroupedQuerySet(QuerySet):
+    def __init__(self, model=None, query=None, using=None, hints=None):
+        super(GroupedQuerySet, self).__init__(model, query, using, hints)
+        self.query = query or GroupedQuery(self.model)
+
+    def group_by(self, *field_names):
+        obj = self._clone()
+        obj.query.clear_grouping()
+        obj.query.add_grouping(*field_names)
+        return obj
+
+
+class GroupedManager(Manager):
+    def __init__(self):
+        super(GroupedManager, self).__init__()
+        self._queryset_class = GroupedQuerySet