nodejs连接mysql错误
我使用mysql和express来写一个简单的login系统。
database.js：
var mysql = require('mysql'); var config = require('../config/config'); var pool = mysql.createPool(config.mysql_dev); var query=function(sql,callback){ pool.getConnection(function(err,conn){ if(err) console.log("POOL ==> " + err); else{ conn.query(sql,function(qerr,vals,fields){ //release connection conn.release(); callback(qerr,vals,fields); }); } }); }; module.exports=query; index.js：
router.post('/login',function(req,res){ var query = require('../modules/database'); query("select * from managers where ManagerID =10001",function(err,vals,fields){ var temp=JSON.stringify(vals); var manager = JSON.parse(temp)[0]; if(req.body.password===manager.password){ req.session.manager = manager; res.redirect('/home'); } res.send('ID or password wrong!'); }); });
但是，每当我得到这个错误：
/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/Parser.js:77 throw err; // Rethrow non-MySQL errors ^ Error: Can't set headers after they are sent. at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11) at ServerResponse.header (/opt/workspace/project/nodejs-demo/node_modules/express/lib/response.js:718:10) at ServerResponse.send (/opt/workspace/project/nodejs-demo/node_modules/express/lib/response.js:163:12) at /opt/workspace/project/nodejs-demo/routes/index.js:40:7 at Query._callback (/opt/workspace/project/nodejs-demo/modules/database.js:16:17) at Query.Sequence.end (/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/sequences/Sequence.js:96:24) at Query._handleFinalResultPacket (/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/sequences/Query.js:144:8) at Query.EofPacket (/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/sequences/Query.js:128:8) at Protocol._parsePacket (/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/Protocol.js:280:23) at Parser.write (/opt/workspace/project/nodejs-demo/node_modules/mysql/lib/protocol/Parser.js:73:12)
如何解决？ 我不知道如何解决它，并寻找很长一段时间。 如果我描述不清楚，只是评论，我会添加我知道的任何东西。
我在代码中的注释中解释了你的问题。
router.post('/login',function(req,res){ var query = require('../modules/database'); query("select * from managers where ManagerID =10001",function(err,vals,fields){ var temp=JSON.stringify(vals); var manager = JSON.parse(temp)[0]; if(req.body.password===manager.password){ req.session.manager = manager; //You are redirecting user to home res.redirect('/home'); //You should add 'return' return; } //This will only accessible if password is not match res.send('ID or password wrong!'); }); });
您在以下代码段中遇到了问题。
if(req.body.password===manager.password){ req.session.manager = manager; res.redirect('/home'); } res.send('ID or password wrong!');
从错误堆栈跟踪中可以清楚地看到，您正在尝试在发送之后设置标头。 这意味着if语句首先执行，如果它是真的，它将redirect到/home ，之后它将退出if子句并尝试向用户发送消息。
可能的scheme
if(req.body.password===manager.password){ req.session.manager = manager; res.redirect('/home'); } else { res.send('ID or password wrong!'); }
检查它，如果它可以帮助你。
我应该回来，如果：
if(req.body.password===manager.password) { req.session.manager = manager; res.redirect('/home'); return; }