1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
Dougrain
========
Dougrain is a Python library to help you work with the JSON variant of the
`Hypertext Application Language <http://stateless.co/hal_specification.html>`_
(HAL). It uses Python objects to represent the JSON document, so you can use
it with whichever JSON library you prefer.
Status
------
.. image:: https://travis-ci.org/wharris/dougrain.png?branch=master
:alt: build status
:target: https://travis-ci.org/wharris/dougrain
This is a pre-release version. It usually works pretty well, but the API may
have breaking changes in minor releases until version 1.0. The HAL
specification is still being developed, so Dougrain is unlikely to have a
stable API until HAL itself is stable.
Compatibility
-------------
JSON HAL drafts **3**, **4**, and **5**. Python **2.7**, **3.2**, and **3.3**.
This version conforms to `JSON Hypermedia API Language Internet Draft 5
<http://tools.ietf.org/html/draft-kelly-json-hal-05>`_,
but it can also work with JSON from
`Draft 4 <http://tools.ietf.org/html/draft-kelly-json-hal-04>`_ and
`Draft 3 <http://tools.ietf.org/html/draft-kelly-json-hal-03>`_.
The draft version can be explicitly selected when the document is constructed,
but the default behavior is for documents to automatically detect which draft
to use.
This version is tested on Python 2.7, including PyPy, Python 3.2, and
Python 3.3.
Installation
------------
You'll probably need to use sudo on the install commands, or run in a
virtualenv.
The easiest way to install the current release is to use pip:
::
$ pip install dougrain
You can install a local copy of the source in the usual way:
::
$ cd dougrain
$ pip install -r requirements.txt
$ python setup.py install
Example
-------
``Document.from_object`` loads HAL data from a ``dict``:
::
>>> from dougrain import Document
>>> doc = Document.from_object(
... {
... "_embedded": {
... "r:post": {
... "_links": {
... "self": {
... "href": "/1"
... },
... "r:site": {
... "href": "/"
... }
... },
... "name": "First child"
... }
... },
... "welcome": "Hi there!",
... "_links": {
... "curies": [
... {
... "href": "http://localhost/rels/{rel}",
... "name": "r",
... "templated": True
... }
... ],
... "self": {
... "href": "/"
... },
... "r:post": {
... "href": "/1"
... },
... "r:tags": {
... "href": "/tags"
... }
... }
... },
... base_uri="http://localhost/")
``Document`` instances provide methods to interrogate the document's
properties, links, and embedded resources.
::
>>> doc.properties['welcome']
'Hi there!'
>>> doc.links['r:tags'].url()
'http://localhost/tags'
>>> doc.embedded['r:post'].url()
'http://localhost/1'
Link relations can be specified using CURIEs or URI references:
::
>>> doc.links['r:tags'].url()
'http://localhost/tags'
>>> doc.links['/rels/tags'].url()
'http://localhost/tags'
``Builder`` provides a lightweight API for building HAL resources from scratch.
Many of ``Builder``'s methods can be chained:
::
>>> from dougrain import Builder
>>> new_post = (Builder("/2").set_property('name', "Second Child")
... .add_curie('admin', "/adminrels/{rel}")
... .add_link('admin:privacy', "/2/privacy"))
>>> import json
>>> print(json.dumps(new_post.as_object(), indent=2))
{
"_links": {
"curies": [
{
"href": "/adminrels/{rel}",
"name": "admin",
"templated": true
}
],
"self": {
"href": "/2"
},
"admin:privacy": {
"href": "/2/privacy"
}
},
"name": "Second Child"
}
``Builder`` and ``Document`` can be used together. For example,
``Document.embed`` will accept a ``Builder`` instance:
::
>>> doc.embed('r:post', new_post)
>>> [post.properties['name'] for post in doc.embedded['/rels/post']]
['First child', 'Second child']
|