我有连接到数据库并管理连接的 database.js 文件我导出连接并在我的应用程序中重用它
var mysql = require('mysql');
pool = mysql.createPool({
host: cfg.mysql.host,
user: cfg.mysql.user,
password: cfg.mysql.pass,
database: cfg.mysql.db,
port: cfg.mysql.port
});
function handleDisconnect() {
pool.getConnection(function(err, cnt) {
module.exports.connection = cnt;
});
pool.on('error', function (err) {
console.log(err);
});
};
handleDisconnect();
process.on('uncaughtException', function (err) {
console.error(err.code);
if(err.code === "PROTOCOL_CONNECTION_LOST")
handleDisconnect();
console.log("Node NOT Exiting...");
});
应用程序.js
var db = require('./database');
app.get('/test', function(req, res) {
db.connection.query('SELECT * from table', function(err, result) {
console.log(result);
});
}
这很好用。我的问题是当 mysql 服务器断开连接时。我通过调用 handleDisconnect() 函数来获取新连接来处理此错误。但是，当发生这种情况时，当我导航到我的浏览器/test 时，我的 app.js 中的连接未定义
TypeError: Cannot call method 'query' of undefined
想法？
最佳答案
您可以在数据库服务器上的每个查询之后简单地将连接放回池中 这是一个例子
db.js
var mysql = require('mysql');
var pool = mysql.createPool({
host : 'localhost',
user : 'root',
password : 'root',
database : 'test',
port: 8889
});
exports.getConnection = function(callback) {
pool.getConnection(function(err, connection) {
callback(err, connection);
});
};
app.js
var db = require('./db');
var http = require("http");
var server = http.createServer(function(request, response) {
db.getConnection(function(err, connection){
if(!err){
connection.query('SELECT * from users' , function(err, rows) {
var users = '';
for (var i = 0; i < rows.length; i++) {
users += rows[i].name + "<br />";
}
connection.release(); // always put connection back in pool after last query
response.writeHead(200, {"Content-Type": "text/html"});
response.write("<!DOCTYPE html>");
response.write("<html>");
response.write("<head>");
response.write("<title>Hello World Page</title>");
response.write("</head>");
response.write("<body>");
response.write(users);
response.write("</body>");
response.write("</html>");
response.end();
});
}else{
response.writeHead(200, {"Content-Type": "text/html"});
response.write("<!DOCTYPE html>");
response.write("<html>");
response.write("<head>");
response.write("<title>Hello World Page</title>");
response.write("</head>");
response.write("<body>");
response.write(err.toString());
response.write("</body>");
response.write("</html>");
response.end();
}
});
});
server.listen(9999);
console.log("Server is listening localhost:9999");
关于javascript - module.exports 作用域和 node-mysql，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19606647/