Python3: JSON POST Request WITHOUT requests library

Question

I want to send JSON encoded data to a server using only native Python libraries. I love requests but I simply can't use it because I can't use it on the machine which runs the script. I need to do it without.

newConditions = {"con1":40, "con2":20, "con3":99, "con4":40, "password":"1234"} 
params = urllib.parse.urlencode(newConditions)
params = params.encode('utf-8')

req = urllib.request.Request(conditionsSetURL, data=params)
urllib.request.urlopen(req)

My server is a local WAMP server. I always get an

urllib.error.HTTPError: HTTP Error 500: Internal Server Error

I am 100% sure that this is NOT a server issue, because the same data, with the same url, on the same machine, with the same server works with the requests library and Postman.

score 78 · Accepted Answer · answered Aug 25 '14 at 17:51

78

You are not posting JSON, you are posting a application/x-www-form-urlencoded request.

Encode to JSON and set the right headers:

import json

newConditions = {"con1":40, "con2":20, "con3":99, "con4":40, "password":"1234"} 
params = json.dumps(newConditions).encode('utf8')
req = urllib.request.Request(conditionsSetURL, data=params,
                             headers={'content-type': 'application/json'})
response = urllib.request.urlopen(req)

Demo:

>>> import json
>>> import urllib.request
>>> conditionsSetURL = 'http://httpbin.org/post'
>>> newConditions = {"con1":40, "con2":20, "con3":99, "con4":40, "password":"1234"} 
>>> params = json.dumps(newConditions).encode('utf8')
>>> req = urllib.request.Request(conditionsSetURL, data=params,
...                              headers={'content-type': 'application/json'})
>>> response = urllib.request.urlopen(req)
>>> print(response.read().decode('utf8'))
{
  "args": {}, 
  "data": "{\"con4\": 40, \"con2\": 20, \"con1\": 40, \"password\": \"1234\", \"con3\": 99}", 
  "files": {}, 
  "form": {}, 
  "headers": {
    "Accept-Encoding": "identity", 
    "Connection": "close", 
    "Content-Length": "68", 
    "Content-Type": "application/json", 
    "Host": "httpbin.org", 
    "User-Agent": "Python-urllib/3.4", 
    "X-Request-Id": "411fbb7c-1aa0-457e-95f9-1af15b77c2d8"
  }, 
  "json": {
    "con1": 40, 
    "con2": 20, 
    "con3": 99, 
    "con4": 40, 
    "password": "1234"
  }, 
  "origin": "84.92.98.170", 
  "url": "http://httpbin.org/post"
}

answered Aug 25 '14 at 17:51

Martijn Pieters

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3

Where is the type of request (i.e. `post`) identified? – Startec Jul 21 '15 at 07:44
6

@Startec: by using the `data` parameter the `Request` object switches from GET to POST. – Martijn Pieters Jul 21 '15 at 07:45
@MartijnPieters Ahh, I see, and does Python (without requests) support any other methods (such as `delete` or `trace`)? – Startec Jul 21 '15 at 07:47
2

@Startec: You can't. See [How to make HTTP DELETE method using urllib2?](http://stackoverflow.com/q/4511598) for work-arounds. – Martijn Pieters Jul 21 '15 at 07:48
@MartijnPieters why do you want to use `dumps` to make a string out of the json? In apps like Postman you send the raw json file, (where curly braces would not be commented out) – Startec Aug 19 '15 at 19:27
2

@Startec: `newConditions` is a *Python dictionary*, not a JSON string. – Martijn Pieters Aug 19 '15 at 19:29
@MartijnPieters The use of `json.dumps` makes all `newConditions` strings: Including parameters that used to be `ints` (such as `con1`) Is this up to the server to decode into the correct types? – Startec Aug 21 '15 at 21:34
3

@Startec: no, `json.dumps()` produces one *JSON encoded string*, in which the integers are still (JSON) integers. Any compliant JSON decoder will give you integers again. – Martijn Pieters Aug 21 '15 at 21:36

Python3: JSON POST Request WITHOUT requests library

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