path: root/djangorestframework/mixins.py

"""
The :mod:`mixins` module provides a set of reusable `mixin`
classes that can be added to a `View`.
"""

from django.contrib.auth.models import AnonymousUser
from django.core.paginator import Paginator
from django.db.models.fields.related import ForeignKey
from django.http import HttpResponse

from djangorestframework import status
from djangorestframework.renderers import BaseRenderer
from djangorestframework.resources import Resource, FormResource, ModelResource
from djangorestframework.response import Response, ErrorResponse
from djangorestframework.utils import as_tuple, MSIE_USER_AGENT_REGEX
from djangorestframework.utils.mediatypes import is_form_media_type, order_by_precedence

from StringIO import StringIO


__all__ = (
    # Base behavior mixins
    'RequestMixin',
    'ResponseMixin',
    'AuthMixin',
    'ResourceMixin',
    # Reverse URL lookup behavior
    'InstanceMixin',
    # Model behavior mixins
    'ReadModelMixin',
    'CreateModelMixin',
    'UpdateModelMixin',
    'DeleteModelMixin',
    'ListModelMixin'
)


########## Request Mixin ##########

class RequestMixin(object):
    """
    `Mixin` class to provide request parsing behavior.
    """

    _USE_FORM_OVERLOADING = True
    _METHOD_PARAM = '_method'
    _CONTENTTYPE_PARAM = '_content_type'
    _CONTENT_PARAM = '_content'

    """
    The set of request parsers that the view can handle.

    Should be a tuple/list of classes as described in the :mod:`parsers` module.
    """
    parsers = ()

    @property
    def method(self):
        """
        Returns the HTTP method.

        This should be used instead of just reading :const:`request.method`, as it allows the `method`
        to be overridden by using a hidden `form` field on a form POST request.
        """
        if not hasattr(self, '_method'):
            self._load_method_and_content_type()
        return self._method


    @property
    def content_type(self):
        """
        Returns the content type header.

        This should be used instead of ``request.META.get('HTTP_CONTENT_TYPE')``,
        as it allows the content type to be overridden by using a hidden form
        field on a form POST request.
        """
        if not hasattr(self, '_content_type'):
            self._load_method_and_content_type()
        return self._content_type


    @property
    def DATA(self):
        """
        Parses the request body and returns the data.

        Similar to ``request.POST``, except that it handles arbitrary parsers,
        and also works on methods other than POST (eg PUT).
        """
        if not hasattr(self, '_data'):
            self._load_data_and_files()
        return self._data


    @property
    def FILES(self):
        """
        Parses the request body and returns the files.
        Similar to ``request.FILES``, except that it handles arbitrary parsers,
        and also works on methods other than POST (eg PUT).
        """
        if not hasattr(self, '_files'):
            self._load_data_and_files()
        return self._files


    def _load_data_and_files(self):
        """
        Parse the request content into self.DATA and self.FILES.
        """
        if not hasattr(self, '_content_type'):
            self._load_method_and_content_type()

        if not hasattr(self, '_data'):
            (self._data, self._files) = self._parse(self._get_stream(), self._content_type)


    def _load_method_and_content_type(self):
        """
        Set the method and content_type, and then check if they've been overridden.
        """
        self._method = self.request.method
        self._content_type = self.request.META.get('HTTP_CONTENT_TYPE', self.request.META.get('CONTENT_TYPE', ''))
        self._perform_form_overloading()


    def _get_stream(self):
        """
        Returns an object that may be used to stream the request content.
        """
        request = self.request

        try:
            content_length = int(request.META.get('CONTENT_LENGTH', request.META.get('HTTP_CONTENT_LENGTH')))
        except (ValueError, TypeError):
            content_length = 0

        # TODO: Add 1.3's LimitedStream to compat and use that.
        # NOTE: Currently only supports parsing request body as a stream with 1.3
        if content_length == 0:
            return None
        elif hasattr(request, 'read'):
             return request
        return StringIO(request.raw_post_data)


    def _perform_form_overloading(self):
        """
        If this is a form POST request, then we need to check if the method and content/content_type have been
        overridden by setting them in hidden form fields or not.
        """

        # We only need to use form overloading on form POST requests.
        if not self._USE_FORM_OVERLOADING or self._method != 'POST' or not is_form_media_type(self._content_type):
            return

        # At this point we're committed to parsing the request as form data.
        self._data = data = self.request.POST.copy()
        self._files = self.request.FILES

        # Method overloading - change the method and remove the param from the content.
        if self._METHOD_PARAM in data:
            # NOTE: unlike `get`, `pop` on a `