Duo A powerful, dynamic, pythonic interface to AWS DynamoDB
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Duo Description

duo is a Python module that provides a few straightforward, Pythonic abstractions for working with Amazon Web Services' DynamoDB. It's a very light wrapper around boto.dynamodb.layer2, so you have full access to that excellent library when you need it, but you don't have to sweat the details when you don't.Usage:duo is made up of one module:>>> import duoThe module isn't very big (at the time of this writing, ~550 lines). If you want to know how something works, you should read it.Pre-create your tables in the AWS console, then write simple classes to access them. duo.Table Sub-classes are automatically registered with the db:>>> class MyHashKeyTable(duo.Table):... table_name = 'my_hashkey_table'... hash_key_name = 'slug'... range_key_name = None # Implicit defaultduo.Item is a thin wrapper around boto.dynamodb.items.Item, with lots of syntactic sugar. duo.Item sub-classs are automatically registered with the db:>>> import datetime>>> class MyHashKeyItem(duo.Item):... table_name = 'my_hashkey_table'... hash_key_name = 'slug'...... slug = duo.UnicodeField()... my_field = duo.UnicodeField(default='foo')... on_this_date = duo.DateField(default=lambda o: datetime.date.today())Databases and Tables use dict-like access syntax:>>> db = duo.DynamoDB(key='access_key', secret='secret_key')>>> # The correct Table sub-class is matched by table name:>>> table = duo.DynamoDB>>> # The correct Item sub-class is matched by table name:>>> item = table>>> # Items are actually dict subclasses, but that's not where the>>> # fun is. They can only store unicode strings and integers:>>> itemu'new-item'Specify a field on an Item sub-class to get useful data types:>>> item.is_newTrue>>> # A field doesn't exist initially...>>> itemTraceback (most recent call last): File "...", line 1, in itemKeyError: 'my_field'>>> # But we specified a default.>>> item.my_field'foo'>>> # The default, once accessed, gets populated:>>> item'foo'>>> # Or we can set our own value...>>> item.my_field = 'bar'>>> item'bar'>>> # Finally, we save it to DynamoDB.>>> item.put()>>> item.is_newFalseCaching:Duo integrates with any cache that implements a python-memcached-compatible interface, namely, the following:import pylibmccache = pylibmc.Client()cache.get(< keyname >)cache.set(< keyname >, < duration-in-seconds >)cache.delete(< keyname >)Integrate caching by passing the cache to the db constructor:>>> import duo>>> db = duo.DynamoDB(key='access_key', secret='secret_key', cache=cache)You can also specify a cache object on a per-table or per-item basis:>>> class MyHashKeyTable(duo.Table): ... cache = pylibmc.Client() ... ... table_name = 'my_hashkey_table' ... hash_key_name = 'slug' ... range_key_name = None # Implicit defaultCaching is turned off by default, but you can turn it on by specifying a cache_duration as an integer (0 is forever):>>> class MyHashKeyItem(duo.Item):... cache_duration = 30 # 30 seconds...... table_name = 'my_hashkey_table'... hash_key_name = 'slug'...... slug = duo.UnicodeField()... my_field = duo.UnicodeField(default='foo')... on_this_date = duo.DateField(default=lambda o: datetime.date.today())Cache keys are determined by hash key, range key, and a cache prefix (set on the Table). By default, the cache prefix is the table name:>>> table = duo.DynamoDB>>> item = table>>> item.cache_prefix is NoneTrue>>>item._cache_key'my_hashkey_table_new-item'>>> MyHashKeyTable.cache_prefix = 'hello_world'>>> item._get_cache_key()'hello_world_new-item'Product's homepage

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