Aggregates

Aggregates for Django.

Description

Aggregates allow acces to the attributes of a set of objects or dictionaries through a single interface.

Installation

The following command will install the package:

$ python setup.py install

The following command will install the package in development mode:

$ python setup.py develop

Tests

The following command will run the tests:

$ python setup.py test

Contents

class Aggregate

Base class for all aggregates. Subclass this class to create a custom aggregate.

class FirstAggregate

Aggregate that returns the first value for a field.

class AllAggregate

Aggregate that returns all values for a field.

class Collection

Base class for all collections. Subclass this class to create a custom collection, adding the required aggregates.

Usage

1. Define a custom collection, adding the required aggregates:

   >>> from aggregates import FirstAggregation, AllAggregation
   >>> from aggregates import Collection
   >>> class MyCollection(Collection):
   ...     field1 = FirstAggregation()
   ...     field2 = AllAggregation()
   

2. Create a collection, containing the items:

   >>> my_items = [{"field1": 1, "field2": 3, "field3": 5},
   ...             {"field1": 2, "field2": 4, "field3": 6}]
   >>> my_collection = MyCollection(my_items)
   

3. Access the fields through the collection:

   >>> my_collection.field1
   1
   >>> my_collection.field2
   [3, 4]
   >>> my_collection.field3
   Traceback (most recent call last):
     ...
   AttributeError: 'MyCollection' object has no attribute 'field3'
   

Contibutors

• Bert Vanderbauwhede (bert.vanderbauwhede@ugent.be), original author