TypeError：无法读取nodejs中未定义的属性“ id”

Question

I'm struggling to make a function which selects from database based on the id entered in a textbox. I wrote the code, but it shows in console this error and I can't figure why: TypeError: Cannot read property 'id' of undefined .

Code I have so far:

Client-side:

function select()
            {
                var id = $('#nr_reg').val();
                $.ajax({
                    type: 'post',
                    url: '/id',
                    data : {
                        id: id
                    },
                    succes: function(data){
                        var id = data.id;
                        alert(id);
                        $('#optic').val(id);
                    },
                    error: function(err){
                        console.log(err);
                    }

                }); 
            }

Server-side:

app.post('/id', function(req,res) {

    var data = req.body;
    var id = data.id;
    console.log(id);
    var query = "SELECT * FROM Control WHERE id=" +id;
    connection.query(query, function(error, result) {
            console.log(result);
            res.send(result);
    });
});

LE: Function select:

function select()
            {

                var id = $('#nr_reg').val();
                $.ajax({
                    type: 'post',
                    dataType: 'json',
                    url: '/id',
                    data : {
                        id: id
                    },
                    success: function(data){    
                        data = JSON.parse(data);                    
                        var id = data.id;
                        alert("merge");
                        $('#optic').val(id);
                    },
                    error: function(err){
                        console.log(err);
                    }

                }); 
            }

Answer 1

You said your error is on server side? Add a body parser to your express app:

1st Install body-parser:

npm install body-parser -s

The include this in your app:

var express = require('express');
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.post(/*....*/);

Your app.post must be AFTER app.use line.
Full example here
BTW this is a duplicate of this

Answer 2

Make sure you've require d body-parser . And use bodyParser.urlencoded .

var bodyParser = require('body-parser');

app.use(bodyParser.urlencoded({ extended: false }));

This should be before your .post route definition.

EDIT:

Before all this, you must do npm install body-parser :)