210 lines
7.6 KiB
Python
210 lines
7.6 KiB
Python
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"""
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Parsers are used to parse the content of incoming HTTP requests.
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They give us a generic way of being able to handle various media types
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on the request, such as form content or json encoded data.
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"""
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import codecs
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from django.conf import settings
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from django.core.files.uploadhandler import StopFutureHandlers
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from django.http import QueryDict
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from django.http.multipartparser import ChunkIter
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from django.http.multipartparser import \
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MultiPartParser as DjangoMultiPartParser
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from django.http.multipartparser import MultiPartParserError
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from rest_framework import renderers
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from rest_framework.compat import parse_header_parameters
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from rest_framework.exceptions import ParseError
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from rest_framework.settings import api_settings
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from rest_framework.utils import json
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class DataAndFiles:
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def __init__(self, data, files):
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self.data = data
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self.files = files
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class BaseParser:
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"""
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All parsers should extend `BaseParser`, specifying a `media_type`
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attribute, and overriding the `.parse()` method.
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"""
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media_type = None
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def parse(self, stream, media_type=None, parser_context=None):
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"""
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Given a stream to read from, return the parsed representation.
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Should return parsed data, or a `DataAndFiles` object consisting of the
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parsed data and files.
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"""
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raise NotImplementedError(".parse() must be overridden.")
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class JSONParser(BaseParser):
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"""
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Parses JSON-serialized data.
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"""
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media_type = 'application/json'
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renderer_class = renderers.JSONRenderer
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strict = api_settings.STRICT_JSON
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def parse(self, stream, media_type=None, parser_context=None):
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"""
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Parses the incoming bytestream as JSON and returns the resulting data.
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"""
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parser_context = parser_context or {}
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encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
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try:
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decoded_stream = codecs.getreader(encoding)(stream)
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parse_constant = json.strict_constant if self.strict else None
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return json.load(decoded_stream, parse_constant=parse_constant)
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except ValueError as exc:
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raise ParseError('JSON parse error - %s' % str(exc))
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class FormParser(BaseParser):
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"""
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Parser for form data.
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"""
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media_type = 'application/x-www-form-urlencoded'
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def parse(self, stream, media_type=None, parser_context=None):
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"""
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Parses the incoming bytestream as a URL encoded form,
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and returns the resulting QueryDict.
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"""
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parser_context = parser_context or {}
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encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
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return QueryDict(stream.read(), encoding=encoding)
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class MultiPartParser(BaseParser):
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"""
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Parser for multipart form data, which may include file data.
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"""
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media_type = 'multipart/form-data'
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def parse(self, stream, media_type=None, parser_context=None):
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"""
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Parses the incoming bytestream as a multipart encoded form,
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and returns a DataAndFiles object.
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`.data` will be a `QueryDict` containing all the form parameters.
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`.files` will be a `QueryDict` containing all the form files.
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"""
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parser_context = parser_context or {}
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request = parser_context['request']
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encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
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meta = request.META.copy()
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meta['CONTENT_TYPE'] = media_type
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upload_handlers = request.upload_handlers
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try:
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parser = DjangoMultiPartParser(meta, stream, upload_handlers, encoding)
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data, files = parser.parse()
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return DataAndFiles(data, files)
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except MultiPartParserError as exc:
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raise ParseError('Multipart form parse error - %s' % str(exc))
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class FileUploadParser(BaseParser):
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"""
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Parser for file upload data.
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"""
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media_type = '*/*'
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errors = {
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'unhandled': 'FileUpload parse error - none of upload handlers can handle the stream',
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'no_filename': 'Missing filename. Request should include a Content-Disposition header with a filename parameter.',
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}
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def parse(self, stream, media_type=None, parser_context=None):
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"""
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Treats the incoming bytestream as a raw file upload and returns
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a `DataAndFiles` object.
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`.data` will be None (we expect request body to be a file content).
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`.files` will be a `QueryDict` containing one 'file' element.
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"""
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parser_context = parser_context or {}
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request = parser_context['request']
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encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
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meta = request.META
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upload_handlers = request.upload_handlers
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filename = self.get_filename(stream, media_type, parser_context)
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if not filename:
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raise ParseError(self.errors['no_filename'])
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# Note that this code is extracted from Django's handling of
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# file uploads in MultiPartParser.
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content_type = meta.get('HTTP_CONTENT_TYPE',
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meta.get('CONTENT_TYPE', ''))
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try:
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content_length = int(meta.get('HTTP_CONTENT_LENGTH',
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meta.get('CONTENT_LENGTH', 0)))
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except (ValueError, TypeError):
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content_length = None
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# See if the handler will want to take care of the parsing.
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for handler in upload_handlers:
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result = handler.handle_raw_input(stream,
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meta,
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content_length,
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None,
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encoding)
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if result is not None:
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return DataAndFiles({}, {'file': result[1]})
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# This is the standard case.
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possible_sizes = [x.chunk_size for x in upload_handlers if x.chunk_size]
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chunk_size = min([2 ** 31 - 4] + possible_sizes)
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chunks = ChunkIter(stream, chunk_size)
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counters = [0] * len(upload_handlers)
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for index, handler in enumerate(upload_handlers):
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try:
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handler.new_file(None, filename, content_type,
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content_length, encoding)
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except StopFutureHandlers:
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upload_handlers = upload_handlers[:index + 1]
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break
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for chunk in chunks:
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for index, handler in enumerate(upload_handlers):
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chunk_length = len(chunk)
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chunk = handler.receive_data_chunk(chunk, counters[index])
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counters[index] += chunk_length
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if chunk is None:
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break
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for index, handler in enumerate(upload_handlers):
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file_obj = handler.file_complete(counters[index])
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if file_obj is not None:
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return DataAndFiles({}, {'file': file_obj})
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raise ParseError(self.errors['unhandled'])
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def get_filename(self, stream, media_type, parser_context):
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"""
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Detects the uploaded file name. First searches a 'filename' url kwarg.
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Then tries to parse Content-Disposition header.
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"""
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try:
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return parser_context['kwargs']['filename']
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except KeyError:
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pass
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try:
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meta = parser_context['request'].META
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disposition, params = parse_header_parameters(meta['HTTP_CONTENT_DISPOSITION'])
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if 'filename*' in params:
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return params['filename*']
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else:
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return params['filename']
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except (AttributeError, KeyError, ValueError):
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pass
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