Get raw POST body in Python Flask regardless of Content-Type header

Question

Previously  I asked How to get data received in Flask request because request data was empty  The answer explained that request data is the raw post body  but will be empty if form data is parsed   How can I get the raw post body unconditionally    app route      methods   POST    def parse request        data   request data    empty in some cases       always need raw data here  not parsed form data

User · Answer

I created a WSGI middleware that stores the raw body from the environ['wsgi.input'] stream. I saved the value in the WSGI environ so I could access it from request.environ['body_copy'] within my app.

This isn't necessary in Werkzeug or Flask, as request.get_data() will get the raw data regardless of content type, but with better handling of HTTP and WSGI behavior.

This reads the entire body into memory, which will be an issue if for example a large file is posted. This won't read anything if the Content-Length header is missing, so it won't handle streaming requests.

from io import BytesIO

class WSGICopyBody(object):
    def __init__(self, application):
        self.application = application

    def __call__(self, environ, start_response):
        length = int(environ.get('CONTENT_LENGTH') or 0)
        body = environ['wsgi.input'].read(length)
        environ['body_copy'] = body
        # replace the stream since it was exhausted by read()
        environ['wsgi.input'] = BytesIO(body)
        return self.application(environ, start_response)

app.wsgi_app = WSGICopyBody(app.wsgi_app)

request.environ['body_copy']

User · Answer

request data will be empty if request headers  Content-Type   is recognized as form data  which will be parsed into request form  To get the raw data regardless of content type  use request get data     request data calls request get data parse form data True   which results in the different behavior for form data

User · Answer

Use request get data   to get the raw data  regardless of content type  The data is cached and you can subsequently access request data  request json  request form at will   If you access request data first  it will call get data with an argument to parse form data first  If the request has a form content type  multipart form-data  application x-www-form-urlencoded  or application x-url-encoded  then the raw data will be consumed  request data and request json will appear empty in this case

User · Answer

request stream is the stream of raw data passed to the application by the WSGI server  No parsing is done when reading it  although you usually want request get data   instead   data   request stream read     The stream will be empty if it was previously read by request data or another attribute

[python] Get raw POST body in Python Flask regardless of Content-Type header

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