Node.js obtains the processing of php curl post data req.body being empty

Node uses express4 and body-parser to parse php curl data, but the req.body obtained is {}, and the header is set

Prerequisite knowledge:

body-parser does not support the function of parsing multi/form-data. If you are passing binary data or uploading files, you cannot use it.

Node.js body parsing middleware.

This does not handle multipart bodies, due to their complex and typically large nature. For multipart bodies, you may be interested in the following modules:

busboy and connect-busboy
multiparty and connect-multiparty
formidable
multer
This module provides the following parsers:

JSON body parser
Raw body parser
Text body parser
URL-encoded form body parser

Reference:
https://github.com/expressjs/ body-parser#bodyparserurlencodedoptions

PHP code

Java code

function addCurl($url, $type="get", $postData=null)  
    {  
        $ch = curl_init();  
        $headers[] = 'Connection: Keep-Alive';  
        $headres[] = 'Content-Type: application/x-www-form-urlencoded;charset=utf-8';         
        $headers[] = 'Content-Length: ' . strlen(json_encode($postData));  
        //$headres[] = 'Content-Type: application/json';  
        //$headres[] = 'Content-Type: text/html';  
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);  
        curl_setopt($ch, CURLOPT_HEADER, 0);  
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);  
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);  
        if ($type=="get") {  
            curl_setopt($ch, CURLOPT_POST, 0);  
        } else {  
            curl_setopt($ch, CURLOPT_POST, 1);  
            curl_setopt($ch, CURLOPT_POSTFIELDS, urlencode(json_encode($postData)));  
        }  
        curl_setopt($ch, CURLOPT_URL, $url);  
        $data = curl_exec($ch);  
        $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);  
          
        if (curl_errno($ch)) {  
            echo 'Curl error: ' . curl_error($ch) . PHP_EOL;  
            curl_close($ch);  
            return false;  
        }   
        curl_close($ch);  
        return ($code == 200) ? $data : "server error,code: . {$code}";  
    }

node code

Java code

var express = require('express')  
var bodyParser = require('body-parser')  
  
var app = express()  
var urlencodedParser = bodyParser.urlencoded({ extended: false })  
app.use(urlencodedParser, function (req, res) {  
  res.setHeader('Content-Type', 'text/plain')  
  res.write('you posted:\n')  
  res.end(JSON.stringify(req.body, null, 2))  
})  
  
app.listen(3000, function() {  
    console.log('Server is running')  
})

Specified parsing method still does not work. Just go to the source code of body-parser and debug it line by line.

Find urlencode.js

Java code

// determine if request should be parsed  
    if (!shouldParse(req)) {  
      return ('skip parsing'), next()  
    }

This line shouldParse returns false
Then type-is.js/index.js returns false.
var value = req.headers['content-type']

Java code

function typeofrequest(req, types_) {  
  var types = types_  
  // no body  
  if (!hasbody(req)) {  
    return null  
  }  
  
  // support flattened arguments  
  if (arguments.length > 2) {  
    types = new Array(arguments.length - 1)  
    for (var i = 0; i < types.length; i++) {  
      types[i] = arguments[i + 1]  
    }  
  }  
  // request content type  
  var value = req.headers['content-type']  
  return typeis(value, types)  
}

Found that req.headers['content-type'] here is multipart/form-data, and type is application /x-www-form-urlencoded

It turns out that when PHP executes curl, postData is an array, and the data encoding will be set to multipart/form-data

Java code

Note:

Pass an array to CURLOPT_POSTFIELDS, cURL will encode the data into multipart/form-data, but when passing a URL-encoded string, the data will be encoded into application/x-www-form-urlencoded.

Modify php code

Java code

curl_setopt($ch, CURLOPT_POSTFIELDS, urlencode(json_encode($postData)));