How to POST JSON data with Python Requests?

Question

I need to POST a JSON from a client to a server. I'm using Python 2.7.1 and simplejson. The client is using Requests. The server is CherryPy. I can GET a hard-coded JSON from the server (code not shown), but when I try to POST a JSON to the server, I get "400 Bad Request".

Here is my client code:

data = {'sender': 'Alice',
 'receiver': 'Bob',
 'message': 'We did it!'}
data_json = simplejson.dumps(data)
payload = {'json_payload': data_json}
r = requests.post("http://localhost:8080", data=payload)

Here is the server code.

class Root(object):
 def __init__(self, content):
 self.content = content
 print self.content # this works
 exposed = True
 def GET(self):
 cherrypy.response.headers['Content-Type'] = 'application/json'
 return simplejson.dumps(self.content)
 def POST(self):
 self.content = simplejson.loads(cherrypy.request.body.read())

Any ideas?

• Charles R: I was using a stripped down version of an example straight out of the documentation.
• Nick Bastin: My comment still stands - CherryPy does not call class __init__ methods with a content argument (and does not claim to in the link you supply). In the detailed example they have, the user supplies the code that calls __init__ and provides the arguments, which we have not seen here so I have no idea what state your object is in when your # this works comment is relevant.
• Charles R: Are you asking to see the line where the instance is created?
• Nick Bastin: yeah, I was trying to start up your example in order to test it, and I wasn't sure how you were instantiating it.
• amiabl: Alternatively, If you use a tool like Postman to test your API calls, you can generate code snippet. Like snippets in Python that uses the requests package. Postman documentation

Answer 1

Starting with Requests version 2.4.2, you can use the json= parameter (which takes a dictionary) instead of data= (which takes a string) in the call:

>>> import requests
>>> r = requests.post('http://httpbin.org/post', json={"key": "value"})
>>> r.status_code
200
>>> r.json()
{'args': {},
 'data': '{"key": "value"}',
 'files': {},
 'form': {},
 'headers': {'Accept': '*/*',
 'Accept-Encoding': 'gzip, deflate',
 'Connection': 'close',
 'Content-Length': '16',
 'Content-Type': 'application/json',
 'Host': 'httpbin.org',
 'User-Agent': 'python-requests/2.4.3 CPython/3.4.0',
 'X-Request-Id': 'xx-xx-xx'},
 'json': {'key': 'value'},
 'origin': 'x.x.x.x',
 'url': 'http://httpbin.org/post'}

• Charles R: Setting this to the accepted answer since this is more idiomatic as of 2.4.2. Keep in mind, for crazy unicode, this may not work.
• MydKnight: I saw an example of this that took the dict object and performed json.dumps(object) before sending. Don't do this...it messes up your JSON. The above is perfect..you can pass it a python object and it turns into perfect json.
• user3064538: @MydKnight looking at the source code, Requests sets the content type then does json.dumps(your_json) and converts the result from a str to bytes.
• user7259432: I logged into my account especially to give you +1 for this. Thanks. I was stuck for a couple of hours until I saw you could specify json=dict It' a script for Linode DNS API that I am working on. Thank you very much!
• elano7: Before I found this answer I had also to use data=json.dumps(...) but without Content-type: application/json in the header it wouldn't work. This json=... thing works perfect.

Answer 2

It turns out I was missing the header information. The following works:

import requests
url = "http://localhost:8080"
data = {'sender': 'Alice', 'receiver': 'Bob', 'message': 'We did it!'}
headers = {'Content-type': 'application/json', 'Accept': 'text/plain'}
r = requests.post(url, data=json.dumps(data), headers=headers)

• Nick Bastin: Good catch - I saw your application/json in GET and somehow missed that you hadn't provided it on the request. You may also need to make sure that you return something from POST or you might get a 500.
• Charles R: Doesn't seem to be necessary. When I print r, I get <Response [200]>.
• VaidAbhishek: How do I retrieve this json at the server side ?
• Advait Saravade: Little heads up before using json.dumps here. The data parameter of requests works fine with dictionaries. No need for converting to a string.
• chevydog: @lolololol ol It's necessary. You are setting an argument for the function/method you're calling. In this case the function/method is named post(). The left side of the assignment operator = is the parameter name some dev defined (e.g. def post(some_param0, headers, ...):). The righthand side of the assignment operator (i.e. assignment value) is the variable you defined (e.g. headers = { ... }) that also just happens to be called headers in this example. You could rename the right side of the assignment (e.g. the assignment value) to whatever you like!

Answer 3

From requests 2.4.2 (https://pypi.python.org/pypi/requests), the "json" parameter is supported. No need to specify "Content-Type". So the shorter version:

requests.post('http://httpbin.org/post', json={'test': 'cheers'})

Answer 4

Which parameter between data / json / files you need to use depends on a request header named Content-Type (you can check this through the developer tools of your browser).

When the Content-Type is application/x-www-form-urlencoded, use data=:

requests.post(url, data=json_obj)

When the Content-Type is application/json, you can either just use json= or use data= and set the Content-Type yourself:

requests.post(url, json=json_obj)

requests.post(url, data=jsonstr, headers={"Content-Type":"application/json"})

When the Content-Type is multipart/form-data, it's used to upload files, so use files=:

requests.post(url, files=xxxx)

• Olshansky: +1. If you're using curlify to see the request made from the response, the content type header will not be set unless you follow these instructions. print(curlify.to_curl(project.request))
• mkjeldsen: The key realization is that every parameter will perform automagic serialization without regard for the current value of the Content-Type header. Consequently, data=json_obj is basically always incorrect; the value must be stringified first, either explicitly by the caller or implicitly via the json parameter.

Answer 5

The better way is:

url = "http://xxx.xxxx.xx"
data = {
 "cardno": "6248889874650987",
 "systemIdentify": "s08",
 "sourceChannel": 12
}
resp = requests.post(url, json=data)

• Corey Goldberg: this is the same as the accepted answer from 3 years before

Answer 6

headers = {"charset": "utf-8", "Content-Type": "application/json"}
url = 'http://localhost:PORT_NUM/FILE.php'
r = requests.post(url, json=YOUR_JSON_DATA, headers=headers)
print(r.text)

• Corey Goldberg: this is the same as the accepted answer from 8 years before

Answer 7

Works perfectly with python 3.5+

client:

import requests
data = {'sender': 'Alice',
 'receiver': 'Bob',
 'message': 'We did it!'}
r = requests.post("http://localhost:8080", json={'json_payload': data})

server:

class Root(object):
 def __init__(self, content):
 self.content = content
 print self.content # this works
 exposed = True
 def GET(self):
 cherrypy.response.headers['Content-Type'] = 'application/json'
 return simplejson.dumps(self.content)
 @cherrypy.tools.json_in()
 @cherrypy.tools.json_out()
 def POST(self):
 self.content = cherrypy.request.json
 return {'status': 'success', 'message': 'updated'}

• MarkHu: Note/reminder: the json arg automatically adds the content-type header for POST in newer versions of Python.

Answer 8

With current requests you can pass in any data structure that dumps to valid JSON , with the json parameter, not just dictionaries (as falsely claimed by the answer by Zeyang Lin).

import requests
r = requests.post('http://httpbin.org/post', json=[1, 2, {"a": 3}])

this is particularly useful if you need to order elements in the response.

Answer 9

It always recommended that we need to have the ability to read the JSON file and parse an object as a request body. We are not going to parse the raw data in the request so the following method will help you to resolve it.

def POST_request():
 with open("FILE PATH", "r") as data:
 JSON_Body = data.read()
 response = requests.post(url="URL", data=JSON_Body)
 assert response.status_code == 200

Answer 10

I solved it this way:

from flask import Flask, request
from flask_restful import Resource, Api
req = request.json
if not req :
 req = request.form
req['value']