python: catch exception for invalid JSON in requests library-CodePudding

I have pretty old system CentOS-7.4 and python package requests-2.26.0.

import requests
...

try:
   response = requests.post("http://localhost:8000", json={ '' })
except requests.exceptions.RequestException as e:
   print e
except requests.exceptions.InvalidJSONError:
   print "Invalid JSON Error."
...

Since the json passed to post method is invalid, I was expecting that exceptions would catch it, however I'm getting this:

Traceback (most recent call last):
  File "./cfg.py", line 219, in <module>
    response = requests.post(URL, json={ '' })
  File "/usr/lib/python2.7/site-packages/requests/api.py", line 117, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/usr/lib/python2.7/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 528, in request
    prep = self.prepare_request(req)
  File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 466, in prepare_request
    hooks=merge_hooks(request.hooks, self.hooks),
  File "/usr/lib/python2.7/site-packages/requests/models.py", line 319, in prepare
    self.prepare_body(data, files, json)
  File "/usr/lib/python2.7/site-packages/requests/models.py", line 471, in prepare_body
    body = complexjson.dumps(json, allow_nan=False)
  File "/usr/lib64/python2.7/json/__init__.py", line 250, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/usr/lib64/python2.7/json/encoder.py", line 207, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib64/python2.7/json/encoder.py", line 270, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib64/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o)   " is not JSON serializable")
TypeError: set(['']) is not JSON serializable

What am I doing wrong?

CodePudding user response：

Requests uses simplejson or json libraries to encode the JSON data. Anything that raises ValueError is caught and cast to InvalidJSONError, but TypeError is not caught. See here:

try:
    body = complexjson.dumps(json, allow_nan=False)
except ValueError as ve:
    raise InvalidJSONError(ve, request=self)

Your test would work with either of these examples:

a = {}
a["a"] = a
requests.get("http://url", json=a)

requests.get("http://url", json={"a": float("nan")})

Easiest thing to do would be to catch TypeError as well in the except:

try:
    response = requests.post("http://localhost:8000", json={''})
except requests.exceptions.RequestException as e:
    print(e)
except (requests.exceptions.InvalidJSONError, TypeError):
    print("Invalid JSON Error.")