django-rest-framework/djangorestframework/content.py

"""Mixin classes that provide a determine_content(request) method to return the content type and content of a request.
We use this more generic behaviour to allow for overloaded content in POST forms.
"""

class ContentMixin(object):
    """Base class for all ContentMixin classes, which simply defines the interface they provide."""

    def determine_content(self, request):
        """If the request contains content return a tuple of (content_type, content) otherwise return None.
        Note that content_type may be None if it is unset.
        Must be overridden to be implemented."""
        raise NotImplementedError()


class StandardContentMixin(ContentMixin):
    """Standard HTTP request content behaviour.
    See RFC 2616 sec 4.3 - http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3"""

    def determine_content(self, request):
        """If the request contains content return a tuple of (content_type, content) otherwise return None.
        Note that content_type may be None if it is unset."""

        if not request.META.get('CONTENT_LENGTH', None) and not request.META.get('TRANSFER_ENCODING', None):
            return None
        return (request.META.get('CONTENT_TYPE', None), request.raw_post_data)


class OverloadedContentMixin(ContentMixin):
    """HTTP request content behaviour that also allows arbitrary content to be tunneled in form data."""

    """The name to use for the content override field in the POST form.
    Set this to *None* to desactivate content overloading."""
    CONTENT_PARAM = '_content'

    """The name to use for the content-type override field in the POST form.
    Taken into account only if content overloading is activated."""
    CONTENTTYPE_PARAM = '_contenttype'

    def determine_content(self, request):
        """If the request contains content, returns a tuple of (content_type, content) otherwise returns None.
        Note that content_type may be None if it is unset."""
        if not request.META.get('CONTENT_LENGTH', None) and not request.META.get('TRANSFER_ENCODING', None):
            return None
        content_type = request.META.get('CONTENT_TYPE', None)

        if (request.method == 'POST' and self.CONTENT_PARAM and
            request.POST.get(self.CONTENT_PARAM, None) is not None):

            # Set content type if form contains a non-empty CONTENTTYPE_PARAM field
            content_type = None
            if self.CONTENTTYPE_PARAM and request.POST.get(self.CONTENTTYPE_PARAM, None):
                content_type = request.POST.get(self.CONTENTTYPE_PARAM, None)
                request.META['CONTENT_TYPE'] = content_type # TODO : VERY BAD, avoid modifying original request.

            return (content_type, request.POST[self.CONTENT_PARAM])
        else:
            return (content_type, request.raw_post_data)