Added a multipart parser that attempts to parse nested strings as json.

starfields_drf_generics/parsers.py

@@ -0,0 +1,73 @@
+from rest_framework.parsers import BaseParser, DataAndFiles
+from django.http.multipartparser import MultiPartParserError
+from rest_framework.exceptions import ParseError
+from django.http.multipartparser import \
+    MultiPartParser as DjangoMultiPartParser
+from django.conf import settings
+import json
+
+
+class NestedJsonMultiPartParser(BaseParser):
+    """
+    Parser for multipart form data, which may include file data.
+    """
+    media_type = 'multipart/form-data'
+
+    def parse(self, stream, media_type=None, parser_context=None):
+        """
+        Parses the incoming bytestream as a multipart encoded form,
+        and returns a DataAndFiles object.
+        The main difference with the parser from rest_framework.parsers
+        is that it attempts to parse nested strings as json to fit with
+        better with json payloads. I also ensure that a single file is
+        passed per field instead of a list which was erroring out
+        FieldFile.to_internal_value.
+
+        `.data` will be a dict containing all the form parameters.
+        `.files` will be a dict containing all the form files.
+        """
+        parser_context = parser_context or {}
+        request = parser_context['request']
+        encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
+        meta = request.META.copy()
+        meta['CONTENT_TYPE'] = media_type
+        upload_handlers = request.upload_handlers
+
+        try:
+            parser = DjangoMultiPartParser(meta,
+                                           stream,
+                                           upload_handlers,
+                                           encoding)
+            data, files = parser.parse()
+
+            # Attempt to parse the multipart fields as json, this is not
+            # demanding since multiparts exist exclusively for file uploads
+            # which is much more demanding
+            data_dict = {}
+            for key in data.keys():
+                values = data[key]
+                try:
+                    data_dict[key] = json.loads(values)
+                except Exception as e:
+                    data_dict[key] = values
+
+            # Make sure the filenames become file names
+            for filename in files.keys():
+                uploaded_file = files[filename]
+                hasfilename = hasattr(uploaded_file, '_name')
+                hasname = hasattr(uploaded_file, 'name')
+                if hasfilename and not hasname:
+                    uploaded_file.name = uploaded_file._name
+
+            # Turn the monstrous MultiValueDict into a normal dict so that
+            # there is only a single uploaded file per field passed
+            files_dict = {}
+            for key in files.keys():
+                uploaded_file = files[key]
+                if isinstance(uploaded_file, list):
+                    uploaded_file = uploaded_file[0]
+                files_dict[key] = uploaded_file
+
+            return DataAndFiles(data_dict, files_dict)
+        except MultiPartParserError as exc:
+            raise ParseError('Multipart form parse error - %s' % str(exc))