节点js中的JSON错误未定义为发布数据的前缀

我无法发布json到一个小的node.js http服务器。 邮政数据总是在它的前面似乎有一个“未定义的”。 我可能做的很蠢，所以我的道歉！

我启动服务器，并用下面的py脚本发布一些json：

>>node simplehttp.js >>python post.py '{"foo":"bar"}' 

服务器得到这个

 >>Request received: undefined{"foo": "bar"} Invalid JSON:undefined{"foo": "bar"} 

节点http服务器

 var http = require("http"); // http-server var server_http = http.createServer( // Function to handle http:post requests, need two parts to it // http://jnjnjn.com/113/node-js-for-noobs-grabbing-post-content/ function onRequest(request, response) { request.setEncoding("utf8"); request.addListener("data", function(chunk) { request.content += chunk; }); request.addListener("end", function() { console.log("Request received: "+request.content); response.writeHead(200, {"Content-Type": "text/plain"}); response.write("Thanks for sending a message"); response.end(); try { json = JSON.parse(request.content); if(json.m !== undefined){ console.log("m: "+json.m); } } catch (Error) { console.log('Invalid JSON:' + request.content); } }); } ); server_http.listen(9002); 

python脚本来做post

 import sys import json import httplib, urllib, urllib2 # Get parameters if len(sys.argv) < 2: sys.stderr.write('Usage: python post.py [JSON Message]\n') sys.exit(1) values = json.loads(sys.argv[1]) headers = {"Content-type": "application/json"} conn = httplib.HTTPConnection('127.0.0.1', 9002) headers = {"Content-type": "application/json"} conn.request("POST", "", json.dumps(values), headers) response = conn.getresponse() print "response.status: "+response.status print "response.reason: "+response.reason print "response.read: "+response.read() conn.close() 

Answer 1

您必须定义content的初始值：

 function onRequest(request, response) { request.content = ""; 

在第一次调用data事件时， request.content还不存在。 未定义属性的string表示是"undefined" 。

所以，要说明request.content += chunk;后面的机制request.content += chunk; ：

 request.content += chunk; // is equivalent to request.content = request.content + chunk; // but request.content is undefined request.content = undefined + chunk; // String concatenation, so request.content = "undefined" + chunk; // <-- This // Example, chunk = '{}' --> request.content = "undefined{}" // After this step, `request.content` is defined, and future calls to // request.content += chunk; are plain string concatenations.