json posts in micropython

Question

I use the code below in python on a rpi to do json posts

import requests
payload = '{"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}'
r = requests.post('https://my.website/api/observations', data = 
{'post_wrapper':payload})
print r.text

it produces

{"msg": {"remote_pi": "FZtank", "stored_ids": ["8"]}, "msg_type": "receipt"}

I figured it wouldn't be too hard to do the same thing in micropython on a pycom device

import urequests as requests
payload = '{"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}'
r = requests.post('https://my.website/api/observations', data = 
{"post_wrapper":payload})
print(r.text)
r.close()

but it gives

Traceback (most recent call last):
File "<stdin>", line 12, in <module>
File "/flash/lib/urequests.py", line 115, in post
File "/flash/lib/urequests.py", line 100, in request
File "/flash/lib/urequests.py", line 79, in request
TypeError: object with buffer protocol required

The TypeError msg means it wants a string instead of a dictionary for the data

so I tried

import urequests as requests
payload = '{"post_wrapper":{"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}}'
r = requests.post('https://my.website/api/observations', data =payload)
print(r.text)
r.close()

but that gives

{"msg": {"errorText": "Malformed POST - unable to decode JSON"}, "msg_type": 
"error"}

So now I'm confused. Is the problem that the website expects a dictionary & micropython can only send a string?

.

Some further detail: I'm using https://github.com/micropython/micropython-lib/blob/master/urequests/urequests.py but with line 52 changed from ai = usocket.getaddrinfo(host, port, 0, usocket.SOCK_STREAM) to ai = usocket.getaddrinfo(host, port) because it used to throw an error msg about 4 arguments Vs 2. If I run

import urequests as requests
payload = '{"post_wrapper":{"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}}'
r = requests.post('https://my.website/api/observations', data=payload)

or

import urequests as requests
payload = {"post_wrapper":{"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}}
r = requests.post('https://my.website/api/observations', json=payload)

or

import urequests as requests
payload = {"msg_type":"observation_payload","msg": 
{"serial":"FZtank","observations":{"8":{"d":0,"m":"JSON upload 
test","t":"1543540780"}}}}
r = requests.post('https://my.website/api/observations', json= 
{"post_wrapper":payload})

I get the same result

{"msg": {"errorText": "Malformed POST - unable to decode JSON"}, "msg_type": 
"error"}

The TypeError msg means it wants a string not so sure about that, it says it wants an object with a buffer protocol. That might be a string, but there are likely other objects supporting that as well. Looking at the source code at github.com/micropython/micropython-lib/blob/master/urequests/… seems to indicate you can just pass json={'post_wrapper': payload} though? — stijn
– stijn, Commented Nov 30, 2018 at 20:02
I tried that but it says TypeError: 'module' object is not callable. I feel I got close with ujson.dumps but it bleats about library line 51 port=int(port) saying OSError: 128 — Kris Mclean
– Kris Mclean, Commented Dec 1, 2018 at 0:21
I fail to see how changing any argument other than url can effect the port; are you sure that's not a seperate unrelated issue? Also maybe post full error messages including line numbers, that's much easier to get help for. — stijn
– stijn, Commented Dec 1, 2018 at 15:46

Victor Luckwu · Accepted Answer · 2020-10-19 22:00:16Z

3

I was stuck with the same issue here while trying to send push notifications through pushed.co.

I was using data=payload on urequests and getting this TypeError: object with buffer protocol required error. All worked well when I changed to json=payload following @stijn suggestion on his answer.

Steps I did:

on micropython REPL install urequests

import upip
upip.install('micropython-urequests')

for my example the code is

import urequests as requests
payload = {
    "app_key": "your_app_key",
    "app_secret": "your_app_secret",
    "target_type": "your_target_type",
    "content": "Hello from micropython",
}
r = requests.post("https://api.pushed.co/1/push", json=payload)

Probably any other url will do fine too.

answered Oct 19, 2020 at 22:00

Victor Luckwu

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user11696358 · Accepted Answer · 2020-11-16 21:15:55Z

0

I was able to make posts request on micropython dumping data into a json:

import json
import urequests
data = {"mykey": 'myvalue'}
urequests.post(url, data=json.dumps(data))

answered Nov 16, 2020 at 21:15

user11696358

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1 Comment

LapplandsCohan Over a year ago

This didn't work for me, but changing the last line to urequests.post(url, json=data) did.

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