Question

我正在研究一个例子，我试图从这个明确的例子中获得一个雇员实例，但是当我输入localhost：3000/1时，我得到一个空数组。有谁知道我在这里做错了什么？

＆＃13;

'use strict';

const express = require('express');
const app = express();

var employees = [
	{
   "EmployeeID" :1 ,
   "EmployeeName" : "RNA Team",
   "Salary" : "200000",
   "Address" : "Bangalore"
   },
   {
   "EmployeeID" :2 ,
   "EmployeeName" : "Mahesh Samabesh",
   "Salary" : "100000",
   "Address" : "Hydrabad"
   },
   {
   "EmployeeID" :3 ,
   "EmployeeName" : "Rui Figo",
   "Salary" : "50000",
   "Address" : "Dallas"
   },
   {
   "EmployeeID" :4 ,
   "EmployeeName" : "Indradev Jana",
   "Salary" : "456789",
   "Address" : "Los Angles"
   },
   {
   "EmployeeID" :5 ,
   "EmployeeName" : "Suresh Shailesh",
   "Salary" : "1234567",
   "Address" : "Patna"
  }
];

//Get the employees records

app.get('/', function(req, res){
	res.send(employees);
});

//run the server
var server = app.listen(3000, function(){
	var host = server.address().address;
	var port  = server.address().port;

	console.log('Server started and listening at:> http://%s:%s', host, port);
});

//Get single employee record
app.get('/:EmployeeID', function(req, res){
	var employeeID = req.params.EmployeeID;

	//Get Employee Records whose EmployeeID = get the EmployeeID at runtime
	var filteredEmployee = [];

	for(var i=0; i < employees.length; i++){
		if(employees[i].EmployeeID == employeeID){
			filteredEmployee.push(employees[i]);
		}
	} //end Loop
	employees = filteredEmployee;
	console.log(filteredEmployee);
	res.send(employees);
});

＆＃13;

Answer 1

你真的不应该在查询操作中改变你的数据。你可以这样做：

app.get('/:EmployeeID', (req, res) => {
  const employeeID = req.params.EmployeeID;
  // filter the employees without mutating the array, and get the first result
  const [employee] = employees.filter(e => e.EmployeeID === employeeID)
  // if there was a result, send it, otherwise send an error
  res.json(employee ? employee : { error: `Employee with id ${employeeID} not found` })
});

Answer 2

您实际上正在改变您的数据。您的工作方式只能工作一次，然后您的员工数组会发生变化。因此，只需删除employees = filteredEmployee;，然后直接发送res.send(filteredEmployee);。

Answer 3

您正在重新分配您的员工对象。

employees = filteredEmployee;

将您的员工对象设置为单个找到的员工。所以它会第一次工作，而且确实如此。然后任何后续尝试都只会有一名员工。

您只想在循环后执行res.send(filteredEmployee)。

您的代码也会将您的浏览器请求作为员工参数提交给/favicon.ico。

添加它会阻止：

 app.get('/favicon.ico', function(req, res) {
     res.send(204);
 });

修复示例：

'use strict';

const express = require('express');
const app = express();

var employees = [
    {
   "EmployeeID" :1 ,
   "EmployeeName" : "RNA Team",
   "Salary" : "200000",
   "Address" : "Bangalore"
   },
   {
   "EmployeeID" :2 ,
   "EmployeeName" : "Mahesh Samabesh",
   "Salary" : "100000",
   "Address" : "Hydrabad"
   },
   {
   "EmployeeID" :3 ,
   "EmployeeName" : "Rui Figo",
   "Salary" : "50000",
   "Address" : "Dallas"
   },
   {
   "EmployeeID" :4 ,
   "EmployeeName" : "Indradev Jana",
   "Salary" : "456789",
   "Address" : "Los Angles"
   },
   {
   "EmployeeID" :5 ,
   "EmployeeName" : "Suresh Shailesh",
   "Salary" : "1234567",
   "Address" : "Patna"
  }
];

//Get the employees records

app.get('/', function(req, res){
    res.send(employees);
});

//run the server
var server = app.listen(3000, function(){
    var host = server.address().address;
    var port  = server.address().port;

    console.log('Server started and listening at:> http://%s:%s', host, port);
});

app.get('/favicon.ico', function(req, res) {
    res.send(204);
});

//Get single employee record
app.get('/:employeeID', function(req, res){
    var employeeID = req.params.employeeID;

    //Get Employee Records whose EmployeeID = get the EmployeeID at runtime
    var filteredEmployee = [];

    for(var i=0; i < employees.length; i++){
        if(employees[i].EmployeeID == employeeID){
            filteredEmployee.push(employees[i]);
        }
    } //end Loop
    console.log(filteredEmployee);
    res.send(filteredEmployee);
});

在快速响应中得到空数组

3 个答案: