How to write JSON post body to a file in Python

Question

I am new to Python and open system technology. I am developing a http server in python which will be receiving a HTTP POST request from a TPF system in JSON format. I am trying to test my python server from POSTMAN where I send sample JSON POST request to the localhost:8000 running on my machine , what I want is to take the JSON POST body and write to a file.

I have below code which will read the JSON POST body and send back the same response to the client however I am not able to figure out how do I dump same response to the file provided by user:

from http.server import HTTPServer, BaseHTTPRequestHandler
from io import BytesIO
from datetime import datetime
import os.path
import json




class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):

    def do_POST(self):
        print('this is PNR compare service Response')
        infi = input("enter the name of the file (.json extension) to save  compare result : ")
        infi = os.path.normpath(infi)
        fi = open(infi,'a+')
        now = datetime.now()
        dt_string = now.strftime(" %d/%m/%Y %H:%M:%S\n")
        fi.write('this is PNR compare service Response at' + dt_string)
                
        content_length = int(self.headers['Content-Length'])
        body = self.rfile.read(content_length)
        self.send_response(200)
        self.end_headers()      
        response = BytesIO()
        response.write(b'This is POST request. ')
        response.write(b'Received: ')
        response.write(body)
        self.wfile.write(response.getvalue())
        #json.dump(body,fi)  
        #json.dump(response.getvalue(),fi)
        #json.dump(response.getvalue(),fi)
        fi.close()



httpd = HTTPServer(('localhost', 8000), SimpleHTTPRequestHandler)
httpd.serve_forever()

Since my response is Byte format, json.dump fails/takes exception (Object of type bytes is not JSON serializable) because it expects a JSON string. Is there any simple way to directly get JSON body from POST request ? My post request is going to be extremely heavy and will have very large JSON body, so looking for a efficient way to parse and dump the response into the file .

You are already receiving a JSON object. You want to *decode* it with `json.loads`, not *encode* it with `json.dump`. — chepner, Jul 07 '20 at 20:49
thank you ! worked!! :) data = json.loads(body) json.dump(data,fi) — ABHIMANYU Mishra, Jul 07 '20 at 21:40
You don't have to decode it *at all*, if you are simply going to immediately re-encode it. — chepner, Jul 08 '20 at 12:29

p t · Answer 1 · 2020-07-07T21:09:24.967

1

here by example answer:

import json

data = {}
data['people'] = []
data['people'].append({
    'name': 'Larry',
    'website': 'google.com',
    'from': 'Michigan'
})
data['people'].append({
    'name': 'Tim',
    'website': 'apple.com',
    'from': 'Alabama'
})

with open('data.txt', 'w') as outfile:
    json.dump(data, outfile)

You might also try this solution.

edited Jul 07 '20 at 21:09

answered Jul 07 '20 at 20:56

p t

11
2

score 0 · Answer 2 · edited Mar 31 '22 at 08:54

thank you , I somehow managed to do this by below code ( literal_eval and json.dumps then write to file as string), however , i am sure there are better ways to do this, i will keep exploring it further. Thank you All.

from http.server import HTTPServer, BaseHTTPRequestHandler
from io import BytesIO
from datetime import datetime
import os.path
from ast import literal_eval
import json

class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        print('this is PNR compare service Response')
        infi = input("enter the name of the file (.json extension) to save  compare result : ")
        infi = os.path.normpath(infi)
        fi = open(infi,'a+')
        now = datetime.now()
        dt_string = now.strftime(" %d/%m/%Y %H:%M:%S\n")
        fi.write('\nthis is PNR compare service Response at' + dt_string)
                
        content_length = int(self.headers['Content-Length'])
        body = self.rfile.read(content_length)
        self.send_response(200)
        self.end_headers()      
        response = BytesIO()
        response.write(b'This is POST request. ')
        response.write(b'Received: ')
        response.write(body)
        self.wfile.write(response.getvalue())

        data = literal_eval(body.decode('utf8'))
        #s = json.dumps(data, indent=4, sort_keys=True)
        s = json.dumps(data, indent=4, sort_keys=False)
        fi.write(s)
        #json.dump(data,fi)
        
        fi.close()


httpd = HTTPServer(('localhost', 8000), SimpleHTTPRequestHandler)
httpd.serve_forever()

How to write JSON post body to a file in Python

2 Answers2