http在Node.js和Python Flask服务器之间发布了base64 json请求，但是Node收到了不完整的json

Question

I try to send a base64 json form node.js server to python flask server and than return a same base64 code back to node.js server. Flask can successfully receive my json but when it response to node and node try to print out the response. I got a error message say: "Unexpected end of JSON input". I found the reason is node server can not receive the base64 completely. It just only receive a small portion. What is the problem? Is post request has a string limit?

I tested when I change the base64 code to a short string. Node server can receive response normally.

Anyone can help me? Thank you.

This is my code:

<<< Node.js Server >>>

var express = require('express');
var http = require('http');

var app = express();

app.get('/', (req, res) => res.send('Hello World!'));

app.listen(10000, () => console.log('Running on http://localhost:10000'));

postData = JSON.stringify({
    'code': <base64 code or short string here>
});

var options = {
    hostname: 'localhost',
    port: 10001,
    path: '/test',
    method: 'POST',
    headers: {
        'Content-Type': 'application/json',
        'Content-Length': Buffer.byteLength(postData)
    }
};

var req = http.request(options, (res) => {
    res.on('data', (chunk) => {
        var data = JSON.parse(chunk);
        console.log(data.message);
    });
    res.on('end', () => {
        console.log('No more data in response.');
    });
});

req.on('error', (e) => {
    console.error(`problem with request: ${e.message}`);
});

req.write(postData);
req.end();

<<< Python Flask Server >>>

from flask import Flask
from flask import request
from flask import jsonify

app = Flask(__name__)

@app.route('/test', methods=['POST'])
def test():
    request_data = request.get_json()
    print(request_data['code'])
    return jsonify(
        message = request_data['code']
    )

app.run(host='localhost', port=10001)

Answer 1

In NodeJS code, in data event, you will get chunk data(partial data), you need to wait until end event and then parse, following example may help you

var req = http.request(options, (res) => {
    var data = '';
    res.on('data', (chunk) => {
        data += chunk.toString(); // buffer to string
    });
    res.on('end', () => {
        data = JSON.parse(data);
        console.log(data.message);
        console.log('No more data in response.');
    });
});