django-rest-framework/djangorestframework/tests/parsers.py

"""
..
    >>> from djangorestframework.parsers import FormParser
    >>> from djangorestframework.compat import RequestFactory
    >>> from djangorestframework.views import BaseView
    >>> from StringIO import StringIO
    >>> from urllib import urlencode
    >>> req = RequestFactory().get('/')
    >>> some_view = BaseView()
    >>> some_view.request = req  # Make as if this request had been dispatched

FormParser
============

Data flatening
----------------

Here is some example data, which would eventually be sent along with a post request :

    >>> inpt = urlencode([
    ...     ('key1', 'bla1'),
    ...     ('key2', 'blo1'), ('key2', 'blo2'),
    ... ])

Default behaviour for :class:`parsers.FormParser`, is to return a single value for each parameter :

    >>> FormParser(some_view).parse(StringIO(inpt)) == {'key1': 'bla1', 'key2': 'blo1'}
    True

However, you can customize this behaviour by subclassing :class:`parsers.FormParser`, and overriding :meth:`parsers.FormParser.is_a_list` :

    >>> class MyFormParser(FormParser):
    ... 
    ...     def is_a_list(self, key, val_list):
    ...         return len(val_list) > 1

This new parser only flattens the lists of parameters that contain a single value.

    >>> MyFormParser(some_view).parse(StringIO(inpt)) == {'key1': 'bla1', 'key2': ['blo1', 'blo2']}
    True

.. note:: The same functionality is available for :class:`parsers.MultiPartParser`.

Submitting an empty list
--------------------------

When submitting an empty select multiple, like this one ::

    <select multiple="multiple" name="key2"></select>

The browsers usually strip the parameter completely. A hack to avoid this, and therefore being able to submit an empty select multiple, is to submit a value that tells the server that the list is empty ::

    <select multiple="multiple" name="key2"><option value="_empty"></select>

:class:`parsers.FormParser` provides the server-side implementation for this hack. Considering the following posted data :

    >>> inpt = urlencode([
    ...     ('key1', 'blo1'), ('key1', '_empty'),
    ...     ('key2', '_empty'),
    ... ])

:class:`parsers.FormParser` strips the values ``_empty`` from all the lists.

    >>> MyFormParser(some_view).parse(StringIO(inpt)) == {'key1': 'blo1'}
    True

Oh ... but wait a second, the parameter ``key2`` isn't even supposed to be a list, so the parser just stripped it.

    >>> class MyFormParser(FormParser):
    ... 
    ...     def is_a_list(self, key, val_list):
    ...         return key == 'key2'
    ... 
    >>> MyFormParser(some_view).parse(StringIO(inpt)) == {'key1': 'blo1', 'key2': []}
    True

Better like that. Note that you can configure something else than ``_empty`` for the empty value by setting :attr:`parsers.FormParser.EMPTY_VALUE`.
"""
import httplib, mimetypes
from tempfile import TemporaryFile
from django.test import TestCase
from djangorestframework.compat import RequestFactory
from djangorestframework.parsers import MultiPartParser
from djangorestframework.views import BaseView
from StringIO import StringIO

def encode_multipart_formdata(fields, files):
    """For testing multipart parser.
    fields is a sequence of (name, value) elements for regular form fields.
    files is a sequence of (name, filename, value) elements for data to be uploaded as files
    Return (content_type, body)."""
    BOUNDARY = '----------ThIs_Is_tHe_bouNdaRY_$'
    CRLF = '\r\n'
    L = []
    for (key, value) in fields:
        L.append('--' + BOUNDARY)
        L.append('Content-Disposition: form-data; name="%s"' % key)
        L.append('')
        L.append(value)
    for (key, filename, value) in files:
        L.append('--' + BOUNDARY)
        L.append('Content-Disposition: form-data; name="%s"; filename="%s"' % (key, filename))
        L.append('Content-Type: %s' % get_content_type(filename))
        L.append('')
        L.append(value)
    L.append('--' + BOUNDARY + '--')
    L.append('')
    body = CRLF.join(L)
    content_type = 'multipart/form-data; boundary=%s' % BOUNDARY
    return content_type, body

def get_content_type(filename):
    return mimetypes.guess_type(filename)[0] or 'application/octet-stream'

class TestMultiPartParser(TestCase):
    def setUp(self):
        self.req = RequestFactory()
        self.content_type, self.body = encode_multipart_formdata([('key1', 'val1'), ('key1', 'val2')],
        [('file1', 'pic.jpg', 'blablabla'), ('file1', 't.txt', 'blobloblo')])

    def test_multipartparser(self):
        """Ensure that MultiPartParser can parse multipart/form-data that contains a mix of several files and parameters."""
        post_req = RequestFactory().post('/', self.body, content_type=self.content_type)
        view = BaseView()
        view.request = post_req
        parsed = MultiPartParser(view).parse(StringIO(self.body))
        self.assertEqual(parsed['key1'], 'val1')
        self.assertEqual(parsed.FILES['file1'].read(), 'blablabla')