wac 0.9

Writing RESTful API clients.

To write a friendly client for a RESTful API you typically end up doing the following:

• Write HTTP client commands for communicating with the server. These commands do things like marshal payloads, convert errors, invoke request hooks, etc.

• Turn responses deserialized by your client into resource objects (i.e. objectify the response).

• Build up queries (e.g. filter, sort) to access resources matching some criteria in perhaps a particular order.

In the ideal case the client gives your users something approximating an ORM for your resources. This library is intended to assist you in writing such a client provided the API you are consuming complies with some basic expectations:

• Uses HTTP properly.

• Identifies resources using URIs.

• Names nested resources consistently.

Installation

Simply:

$ pip install wac

or if you prefer:

$ easy_install wac

Requirements

• Python >= 2.6, < 3.0

• Requests >= 0.11.1

Usage

Lets work through an example. The code for this example is in example.py.

• First you import wac:

  import wac

• Next define the version of your client:

  __version__ = '1.0'

• Also define the configuration which all Clients will use by default:

  default_config = wac.Config(None)

• Now be nice and define a function for updating the configuration(s):

  def configure(root_url, **kwargs):
      default = kwargs.pop('default', True)
      kwargs['client_agent'] = 'example-client/' + __version__
      if 'headers' not in kwargs:
          kwargs['headers'] = {}
      kwargs['headers']['Accept-Type'] = 'application/json'
      if default:
          default_config.reset(root_url, **kwargs)
      else:
          Client.config = wac.Config(root_url, **kwargs

• Now the big one, define your Client which is what will be used to talk to a server:

  class Client(wac.Client):
  
      config = default_config
  
      def _serialize(self, data):
          data = json.dumps(data, default=self._default_serialize)
          return 'application/json', data
  
      def _deserialize(self, response):
          if response.headers['Content-Type'] != 'application/json':
              raise Exception("Unsupported content-type '{}'"
                  .format(response.headers['Content-Type']))
          data = json.loads(response.content)
          return data

• Then define your base Resource:

  class Resource(wac.Resource):
  
      client = Client()
      registry = wac.ResourceRegistry()

• And finally your actual resources:

  class Playlist(Resource):
  
      uri_spec = wac.URISpec('playlists', 'guid', root='/v1')
  
  
  class Song(Resource):
  
      uri_spec = wac.URISpec('songs', 'guid')

• Done! Now you can do crazy stuff like this:

  import example
  
  example.configure('https://api.example.com', auth=('user', 'passwd'))
  
  q = (example.Playlist.query()
      .filter(Playlist.f.tags.contains('nuti'))
      .filter(~Playlist.f.tags.contains('sober'))
      .sort(Playlist.f.created_at.desc()))
  for playlist in q:
      song = playlist.songs.create(
          name='Flutes',
          length=1234,
          tags=['nuti', 'fluti'])
      song.length += 101
      song.save()

Contributing

Yes please.

History

0.9 (2012-07-25)

• Save serialization fix.

0.8 (2012-07-25)

• Pagination fixes.

0.7 (2012-07-20)

• Misc fixes.

0.3 (2012-05-28)

• Hope you like it.

0.2 (2012-05-01)

• Growing pains.

0.1 (2012-04-01)

• Its alive!