From 223e5c3d9915b538e978a8e2414cdf9d75e1466f Mon Sep 17 00:00:00 2001
From: Konsta Vesterinen <konsta.vesterinen@gmail.com>
Date: Sat, 9 Nov 2013 11:13:29 +0200
Subject: [PATCH] Added more docs for aggregates

---
 sqlalchemy_utils/aggregates.py | 55 ++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/sqlalchemy_utils/aggregates.py b/sqlalchemy_utils/aggregates.py
index aa94ba2..6114f23 100644
--- a/sqlalchemy_utils/aggregates.py
+++ b/sqlalchemy_utils/aggregates.py
@@ -69,8 +69,6 @@ Simple aggregates
         content = sa.Column(sa.UnicodeText)
         thread_id = sa.Column(sa.Integer, sa.ForeignKey(Thread.id))
 
-        thread = sa.orm.relationship(Thread, backref='comments')
-
 
 
 
@@ -155,6 +153,59 @@ Now the net_worth column of Catalog model will be automatically whenever:
 
 
 
+Multiple aggregates per class
+-----------------------------
+
+Sometimes you may need to define multiple aggregate values for same class. If you need
+to define lots of relationships pointing to same class, remember to define the relationships as viewonly when possible.
+
+
+::
+
+
+    from sqlalchemy_utils import aggregated_attr
+
+
+    class Customer(Base):
+        __tablename__ = 'customer'
+        id = sa.Column(sa.Integer, primary_key=True)
+        name = sa.Column(sa.Unicode(255))
+
+        @aggregated_attr('orders')
+        def orders_sum(self):
+            return sa.Column(sa.Integer)
+
+        @orders_sum.expression
+        def orders_sum(self):
+            return sa.func.sum(Order.price)
+
+        @aggregated_attr('open_orders')
+        def open_orders_sum(self):
+            return sa.Column(sa.Integer)
+
+        @open_orders_sum.expression
+        def open_orders_sum(self):
+            return sa.func.sum(Order.price)
+
+
+        orders = sa.orm.relationship('Order')
+
+        open_orders = sa.orm.relationship(
+            'Order',
+            primaryjoin=
+                'db.and_(Order.customer_id == Customer.id, Order.invoiced)',
+            viewonly=True
+        )
+
+
+    class Order(Base):
+        __tablename__ = 'order'
+        id = sa.Column(sa.Integer, primary_key=True)
+        name = sa.Column(sa.Unicode(255))
+        price = sa.Column(sa.Numeric)
+        invoiced = sa.Column(sa.Boolean, default=False)
+        customer_id = sa.Column(sa.Integer, sa.ForeignKey(Customer.id))
+