mawac

Writing RESTful API clients.

Classifiers

Development Status: 4 - Beta
Intended Audience: Developers
License: OSI Approved :: ISC License (ISCL)
Natural Language: English
Programming Language: Python; Python :: 2.7
Topic: Software Development :: Libraries :: Python Modules

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()