How to handle http JSON POST response in MicroPyton? (ESP8266) - html

Question

I'm an absolute beginner in get/post requests and micropython.
I'm programming my ESP8266 Wemos D1 mini as a HTTP server with micropython. My project consists of using a website to control the RGB values of a neopixel matrix hooked up to the D1 (all the code is on my GitHub here: https://github.com/julien123123/NeoLamp-Micro).
Basically, the website contains three sliders: one for Red, one for Green and one for Blue. A javascript code reads the value of each slider and sends it to the micropython code with using the POST method as follows :
getColors = function() {
var rgb = new Array(slider1.value, slider2.value, slider3.value);
return rgb;
};
postColors = function(rgb) {
var xmlhttp = new XMLHttpRequest();
var npxJSON = '{"R":' + rgb[0] + ', "G":' + rgb[1] + ', "B":' + rgb[2] + '}';
xmlhttp.open('POST', 'http://' + window.location.hostname + '/npx', true);
xmlhttp.setRequestHeader('Content-type', 'application/json');
xmlhttp.send(npxJSON);
};
To recieve the resquest in micropython here's my code:
conn, addr = s.accept()
request = conn.recv(1024)
request = str(request)
print(request)
The response prints as follows:
b'POST /npx HTTP/1.1\r\nHost: 192.xxx.xxx.xxx\r\nConnection: keep-alive\r\nContent-Length: 27\r\nOrigin: http://192.168.0.110\r\nUser-Agent: Mozilla/5.0 (X11; CrOS x86_64 10323.46.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.107 Safari/537.36\r\nContent-type: application/json\r\nAccept: */*\r\nReferer: http://192.xxx.xxx.xxx/\r\nAccept-Encoding: gzip, deflate\r\nAccept-Language: fr,en;q=0.9,fr-CA;q=0.8\r\n\r\n{"R":114, "G":120, "B":236}'
The only important bit for me is at the end : {"R":114, "G":120, "B":236}. I want to use those values to change the color values of my neopixel object.
My question to you is how to I process the response so that I keep only the dictionary containing the RGB variables at the end of the response??
Thanks in advance (I'm almost there!)

Answer 1

This is more related to generic python data type. The data type of request is in bytes as indicated by prefix b in b'POST /npx HTTP/1.1...\r\n{"R":114, "G":120, "B":236}'. You will have to use decode() to convert it to string
import json
request = b'POST /npx HTTP/1.1\r\nHost: 192.xxx.xxx.xxx\r\nConnection: keep-alive\r\nContent-Length: 27\r\nOrigin: http://192.168.0.110\r\nUser-Agent: Mozilla/5.0 (X11; CrOS x86_64 10323.46.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.107 Safari/537.36\r\nContent-type: application/json\r\nAccept: */*\r\nReferer: http://192.xxx.xxx.xxx/\r\nAccept-Encoding: gzip, deflate\r\nAccept-Language: fr,en;q=0.9,fr-CA;q=0.8\r\n\r\n{"R":114, "G":120, "B":236}'
data = request.decode() # convert to str
rgb = data.split('\r\n')[-1:] #split the str and discard the http header
for color in rgb:
print(color, type(color))
d = json.loads(color)
print(d, type(d))
The result of color is a str representation of an json object, the d will give you a python dict object to be used for further manipulation:
{"R":114, "G":120, "B":236} <class 'str'>
{'R': 114, 'G': 120, 'B': 236} <class 'dict'>