如何使用 postgresql db 在 express js 中创建回调函数？

Question

如何在这种情况下正确创建回调函数。
如何等待查询执行结果。这是代码片段：

app.post('/validate', urlencodedParser, function (req, res) {
    var data = [
        {username:req.body.user, password:req.body.pwd}
    ];
    var disp = function (data,res, callback) {
        return callback(data,res);
    }
    console.log(disp(data,res, LoginCheck));
});

var LoginCheck = function (data,res) {
    var dbresult = [];
    var client = new pg.Client(conString);
    client.connect();
    var query = client.query("SELECT * FROM employee_details");
    query.on("row", function (row, result) {
        result.addRow(row);
    });
    query.on("end", function (result) {      
        dbresult=result.rows;
        console.log(dbresult);
        return dbresult;        
    });
}

Answer 1

你只需要一个回调函数

app.post('/validate', urlencodedParser, function (req, res) {
  var data = [
  {username:req.body.user, password:req.body.pwd}
  ];

 /* var disp = function (data,res, callback) {
    return callback(data,res,callback2);
  }
  console.log(disp(data,res, LoginCheck));
  */

  LoginCheck(data,res, function(result){

    if(result){

      //do whatever you want

      console.log(result)

    }

  })


});

var LoginCheck = function (data,res,callback2) {
  var dbresult = [];
  var client = new pg.Client(conString);
  client.connect();
  var query = client.query("SELECT * FROM employee_details");
  query.on("row", function (row, result) {
    result.addRow(row);
  });
  query.on("end", function (result) {

    dbresult=result.rows;
    console.log(dbresult);
    return callback2(dbresult);

  });
}

如何使用 postgresql db 在 express js 中创建回调函数？

how to create callback function in express js with postgresql db?

node.js

express

postgresql-9.1