Set default relation query_class to BaseQuery.

Set default query_class for `db.relation`, `db.relationship`, and
  `db.dynamic_loader` to Flask-SQLAlchemy's BaseQuery.

CHANGES

@@ -7,6 +7,8 @@ release.
 Version 0.12
 ````````````
 
+- Set default query_class for `db.relation`, `db.relationship`, and 
+  `db.dynamic_loader` to Flask-SQLAlchemy's BaseQuery.
 
 Version 0.11
 ````````````

flaskext/sqlalchemy.py

@@ -12,6 +12,7 @@
 import re
 import sys
 import time
+import functools
 import sqlalchemy
 from math import ceil
 from functools import partial
@@ -59,13 +60,33 @@ def _make_table(*args, **kwargs):
     return _make_table
 
 
+def _set_default_query_class(d):
+    if 'query_class' not in d:
+        d['query_class'] = BaseQuery
+
+
+def _wrap_with_default_query_class(fn):
+    @functools.wraps(fn)
+    def newfn(*args, **kwargs):
+        _set_default_query_class(kwargs)
+        if "backref" in kwargs:
+            backref = kwargs['backref']
+            if isinstance(backref, basestring):
+                backref = (backref, {})
+            _set_default_query_class(backref[1])
+        return fn(*args, **kwargs)
+    return newfn
+
 
 def _include_sqlalchemy(obj):
     for module in sqlalchemy, sqlalchemy.orm:
         for key in module.__all__:
             if not hasattr(obj, key):
                 setattr(obj, key, getattr(module, key))
     obj.Table = _make_table(obj)
+    obj.relationship = _wrap_with_default_query_class(obj.relationship)
+    obj.relation = _wrap_with_default_query_class(obj.relation)
+    obj.dynamic_loader = _wrap_with_default_query_class(obj.dynamic_loader)
 
 
 class _DebugQueryTuple(tuple):

test_sqlalchemy.py

@@ -187,5 +187,28 @@ def test_basic_pagination(self):
                          [1, 2, None, 8, 9, 10, 11, 12, 13, 14, None, 24, 25])
 
 
+class DefaultQueryClassTestCase(unittest.TestCase):
+
+    def test_default_query_class(self):
+        app = flask.Flask(__name__)
+        app.config['SQLALCHEMY_ENGINE'] = 'sqlite://'
+        app.config['TESTING'] = True
+        db = sqlalchemy.SQLAlchemy(app)
+
+        class Parent(db.Model):
+            id = db.Column(db.Integer, primary_key=True)
+            children = db.relationship("Child", backref = db.backref("parents", lazy='dynamic'), lazy='dynamic')
+        class Child(db.Model):
+            id = db.Column(db.Integer, primary_key=True)
+            parent_id = db.Column(db.Integer, db.ForeignKey('parent.id'))
+        p = Parent()
+        c = Child()
+        c.parent = p
+        self.assertEqual(type(Parent.query), sqlalchemy.BaseQuery)
+        self.assertEqual(type(Child.query), sqlalchemy.BaseQuery)
+        self.assert_(isinstance(p.children, sqlalchemy.BaseQuery))
+        self.assert_(isinstance(c.parents, sqlalchemy.BaseQuery))
+
+
 if __name__ == '__main__':
     unittest.main()