Handling application/json data with bottle - json

Question

I'm trying to write a simple server frontend to a python3 application, using a restful JSON-based protocol. So far, bottle seems the best suited framework for the task (it supports python3, handles method dispatching in a nice way, and easily returns JSON.) The problem is parsing the JSON in the input request.
The documentation only mention request.fields and request.files, both I assume refer to multipart/form-data data. No mention of accessing the request data directly.
Peeking at the source code, I can see a request.body object of type BytesIO. json.load refuses to act on it directly, dying in the json lib with can't use a string pattern on a bytes-like object. The proper way to do it may be to first decode the bytes to unicode characters, according to whichever charset was specified in the Content-Type HTTP header. I don't know how to do that; I can see a StringIO class and assume it may hold a buffer of characters instead of bytes, but see no way of decoding a BytesIO to a StringIO, if this is even possible at all.
Of course, it may also be possible to read the BytesIO object into a bytestring, then decode it into a string before passing it to the JSON decoder, but if I understand correctly, that breaks the nice buffering behavior of the whole thing.
Or is there any better way to do it ?

Answer 1

It seems that io.TextIOWrapper from the standard library does the trick !
def parse(request):
encoding = ... #get encoding from headers
return json.load(TextIOWrapper(request.body, encoding=encoding))

Answer 2

Here's what I do to read in json on a RESTful service with Python3 and Bottle:
import bson.json_util as bson_json
#app.post('/location/API')
def post_json_example():
"""
param: _id, value
return: I usually return something like {"status": "successful", "message": "discription"}
"""
query_string = bottle.request.query.json
query_dict = bson_json.loads(query_string)
_id = query_dict['_id']
value = query_dict['value']
Then to Test
from python3 interpreter, import requests
s = request.Session()
r = s.post('http://youserver.com:8080/location/API?json
{"_id":"540a16663dafb492a0a7626c","value":"test"}')
use r.text to verify what was returned.

Answer 3

I wrote an helper to use the good idea of b0fh.
After 2 weeks on response.json analyzing, I connect to StackOver Flow and understand that we need a work around
Here is:
def json_app_rqt():
# about request
request.accept = 'application/json, text/plain; charset=utf-8'
def json_app_resp():
# about response
response.headers['Access-Control-Allow-Origin'] = _allow_origin
response.headers['Access-Control-Allow-Methods'] = _allow_methods
# response.headers['Access-Control-Allow-Headers'] = _allow_headers
response.headers['Content-Type'] = 'application/json; charset=utf-8'
def json_app():
json_app_rqt()
json_app_resp()
def get_json_request(rqt):
with TextIOWrapper(rqt.body, encoding = "UTF-8") as json_wrap:
json_text = ''.join(json_wrap.readlines())
json_data = json.loads(json_text)
return json_data
For the using, we cand do:
if __name__ == "__main__":
json_app()
#post("/train_control/:control")
def do_train_control(control):
json_app_resp()
data = get_json_request(request)
print(json.dumps(data))
return data
Thanks to all