NodeJs actual combat - to-do list 5 - use MySQL to store to-do items
The previous chapters store to-do items based on memory, so there will be a problem. After the service is restarted, the to-do item data will be lost. This section stores the data in the database.
project structure
The basics you need to know
- MySQL database, SQL statement
- NodeJS web service
Create database, data table
- create database
create database test charset=utf8mb4;
- Create data table
CREATE TABLE `t_todo_list` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`item_name` varchar(50) DEFAULT NULL,
`create_time` datetime DEFAULT NULL,
`complete_time` datetime DEFAULT NULL,
`todo_status` int(11) DEFAULT NULL COMMENT '0-初始状态 1-已完成',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
How NodeJS connects to MySQL and executes SQL
- Install the mysql module npm install mysql
F:\Github\Nodejs\todolist>npm install mysql
- Write demo program connection
Create a database connection pool db
F:\Github\Nodejs\todolist>node
Welcome to Node.js v18.12.1.
Type ".help" for more information.
> const mysql = require('mysql')
undefined
> const db = mysql.createPool({
... host: "127.0.0.1",
... port: 3306,
... user: 'root',
... password: 'shootercheng',
... database: "test"
... })
undefined
> db.query('select 1', (err, result) => {
console.log(result)});
<ref *1> Query {
_events: [Object: null prototype] {
},
_eventsCount: 0,
_maxListeners: undefined,
_callback: [Function: runBound],
_callSite: Error
at Pool.query (F:\Github\Nodejs\todolist\node_modules\mysql\lib\Pool.js:199:23)
at REPL15:1:4
at Script.runInThisContext (node:vm:129:12)
at REPLServer.defaultEval (node:repl:572:29)
at bound (node:domain:433:15)
at REPLServer.runBound [as eval] (node:domain:444:12)
at REPLServer.onLine (node:repl:902:10)
at REPLServer.emit (node:events:525:35)
at REPLServer.emit (node:domain:489:12)
at [_onLine] [as _onLine] (node:internal/readline/interface:425:12),
_ended: false,
_timeout: undefined,
_timer: Timer {
_object: [Circular *1], _timeout: null },
sql: 'select 1',
values: undefined,
typeCast: true,
nestTables: false,
_resultSet: null,
_results: [],
_fields: [],
_index: 0,
_loadError: null,
[Symbol(kCapture)]: false
}
> [ RowDataPacket {
'1': 1 } ]
get current time
> const silly = require('silly-datetime')
undefined
> silly.format(new Date(), 'YYYY-MM-DD HH:mm:ss')
'2022-11-19 20:32:38'
The complete test.js code is as follows
const mysql = require('mysql');
const db = mysql.createPool({
host: "127.0.0.1",
port: 3306,
user: 'root',
password: 'shootercheng',
database: "test"
});
const silly = require('silly-datetime');
function currentTime() {
return silly.format(new Date(), 'YYYY-MM-DD HH:mm:ss');
}
function insertTest() {
db.query('insert into t_todo_list(item_name, create_time) values(?, ?)', ['中文', currentTime()], (err, result) => {
console.log(result);
});
}
function selectTest() {
db.query('select * from t_todo_list where id = ?', ['2'],(err, result) => {
if (err) {
console.log(err);
return;
}
for (var index in result) {
console.log(result[index]);
}
});
}
function updateTest() {
db.query('update t_todo_list set complete_time = ? where id = ?', [currentTime(), 2],
(err, result) => {
console.log(result);
})
}
insertTest();
selectTest();
updateTest();
- Run node test.js to see the following information
F:\Github\Nodejs\todolist>node test.js
RowDataPacket {
id: 2,
item_name: '中文',
create_time: 2022-11-19T09:20:13.000Z,
complete_time: 2022-11-19T12:35:12.000Z
}
OkPacket {
fieldCount: 0,
affectedRows: 1,
insertId: 4,
serverStatus: 2,
warningCount: 0,
message: '',
protocol41: true,
changedRows: 0
}
OkPacket {
fieldCount: 0,
affectedRows: 1,
insertId: 0,
serverStatus: 2,
warningCount: 0,
message: '(Rows matched: 1 Changed: 1 Warnings: 0',
protocol41: true,
changedRows: 1
}
- Problems encountered in writing the demo program.
I just started using the mysql module of nodejs. I didn’t know that the query method is executed asynchronously. I wrote the following method
const mysql = require('mysql');
const db = mysql.createPool({
host: "127.0.0.1",
port: 3306,
user: 'root',
password: 'shootercheng',
database: "test"
});
function selectTest() {
var dataList = [];
db.query('select * from t_todo_list where id = ?', ['2'],(err, result) => {
if (err) {
console.log(err);
return;
}
for (var index in result) {
dataList.push(result[index]);
}
});
console.log(dataList);
return dataList;
}
selectTest();
What is the output of calling this method? Save this method to the js file test_async.js
and find that the data is not stored in the list, indicating that it is executed asynchronously. If you add a delay to the output, wait until the query is executed.
// 输出延时3秒钟，等异步查询数据完毕
setTimeout(() => {
console.log(dataList)}, 3000);
Modify the server code server.js
After the previous demo program, I learned how to use the nodejs mysql module to add, delete, modify and check. It is necessary to modify the original addition, deletion, modification and query of the memory to the addition, deletion, modification and query of the database.
- Add query method
function doQuery(response) {
db.query('select item_name from t_todo_list where todo_status = ?', ['0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
var itemList = [];
for (var i in result) {
itemList.push(result[i].item_name);
}
var data = buildData(CODE_SUCCESS, itemList, '查询成功');
sendMsg(response, JSON.stringify(data));
});
}
- Add method to add to-do items
function doAdd(response, itemData) {
db.query('select count(*) as num from t_todo_list where item_name = ? and todo_status = ?', [itemData,'0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
if (result[0].num > 0) {
var data = buildData(CODE_ERROR, [], itemData + '-待办事项已存在');
sendMsg(response, JSON.stringify(data));
return;
}
db.query('insert into t_todo_list(item_name, create_time, todo_status) values(?, ?, ?)', [itemData, currentTime(), '0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], itemData + '-待办事项添加到数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
doQuery(response);
});
});
}
- Add a method to complete the to-do list
function doCompelete(response, itemData) {
db.query('select count(*) as num from t_todo_list where item_name = ? and todo_status = ?', [itemData, '0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
if (result[0].num == 0) {
var data = buildData(CODE_ERROR, [], itemData + '-待办事项不存在');
sendMsg(response, JSON.stringify(data));
return;
}
db.query('update t_todo_list set complete_time = ?, todo_status = ? where item_name = ?', [currentTime(), '1', itemData], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], itemData + '-更新待办事项失败');
sendMsg(response, JSON.stringify(data));
return;
}
doQuery(response);
});
});
}
- Modify the main method
const server = http.createServer((request, response) => {
var urlParse = parse(request.url);
var urlPath = urlParse.pathname;
var itemData;
if (urlPath == '/add' || urlPath == '/complete') {
itemData = findItemData(urlParse);
if (itemData.length == 0) {
var data = buildData(CODE_ERROR, [], '输入数据有误');
return sendMsg(response, JSON.stringify(data));
}
}
switch (urlPath) {
case '/':
var filePath = 'public/index.html';
var absPath = './' + filePath;
readFile(response, absPath);
break;
case '/query':
doQuery(response);
break;
case '/add':
doAdd(response, itemData);
break;
case '/complete':
doCompelete(response, itemData);
break;
}
});
- complete server.js
const http = require('http');
const fs = require('fs');
const parse = require('url').parse;
const mysql = require('mysql');
const silly = require('silly-datetime');
const db = mysql.createPool({
host: "127.0.0.1",
port: 3306,
user: 'root',
password: 'shootercheng',
database: "test"
});
const hostname = '127.0.0.1';
const port = 3000;
const CODE_ERROR = 0;
const CODE_SUCCESS = 1;
function send404(response) {
response.writeHead(404, {
'Content-Type': 'text/plain'});
response.write('Error 404: resource not found.');
response.end();
}
function sendMsg(response, msg) {
response.writeHead(200, {
'Content-Type': 'application/json;charset=UTF-8'});
response.write(msg);
response.end();
}
function readFile(response, filePath) {
fs.readFile(filePath, (err, data) => {
if (err) {
return send404(response);
}
var html = data.toString();
// html = html.replace('%', Array.from(todoSet).join('</li><li>'));
response.writeHead(200, {
'Content-Type': 'text/html'});
response.end(html);
});
}
function findItemData(urlParse) {
if (urlParse.query.length > 0) {
var queryArray = urlParse.query.split('=');
if (queryArray.length >= 2) {
return decodeURI(queryArray[1]);
}
}
return '';
}
function buildData(code, data, msg) {
// 返回数据
let retData = {
'code':'',
'data': [],
'msg':''
}
retData.code = code;
retData.data = data;
retData.msg = msg;
return retData;
}
/**
* 获取当前时间
* @returns
*/
function currentTime() {
return silly.format(new Date(), 'YYYY-MM-DD HH:mm:ss');
}
/**
* 查询待办数据，并且输出到浏览器
* @param {*} response
*/
function doQuery(response) {
db.query('select item_name from t_todo_list where todo_status = ?', ['0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
var itemList = [];
for (var i in result) {
itemList.push(result[i].item_name);
}
var data = buildData(CODE_SUCCESS, itemList, '查询成功');
sendMsg(response, JSON.stringify(data));
});
}
/**
* 添加待办事项
* @param {*} response
* @param {*} itemData
*/
function doAdd(response, itemData) {
db.query('select count(*) as num from t_todo_list where item_name = ? and todo_status = ?', [itemData,'0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
if (result[0].num > 0) {
var data = buildData(CODE_ERROR, [], itemData + '-待办事项已存在');
sendMsg(response, JSON.stringify(data));
return;
}
db.query('insert into t_todo_list(item_name, create_time, todo_status) values(?, ?, ?)', [itemData, currentTime(), '0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], itemData + '-待办事项添加到数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
doQuery(response);
});
});
}
/**
* 完成待办事项
* @param {*} response
* @param {*} itemData
*/
function doCompelete(response, itemData) {
db.query('select count(*) as num from t_todo_list where item_name = ? and todo_status = ?', [itemData, '0'], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], '查询数据库失败');
sendMsg(response, JSON.stringify(data));
return;
}
if (result[0].num == 0) {
var data = buildData(CODE_ERROR, [], itemData + '-待办事项不存在');
sendMsg(response, JSON.stringify(data));
return;
}
db.query('update t_todo_list set complete_time = ?, todo_status = ? where item_name = ?', [currentTime(), '1', itemData], (err, result) => {
if (err) {
console.log(err);
var data = buildData(CODE_ERROR, [], itemData + '-更新待办事项失败');
sendMsg(response, JSON.stringify(data));
return;
}
doQuery(response);
});
});
}
const server = http.createServer((request, response) => {
var urlParse = parse(request.url);
var urlPath = urlParse.pathname;
var itemData;
if (urlPath == '/add' || urlPath == '/complete') {
itemData = findItemData(urlParse);
if (itemData.length == 0) {
var data = buildData(CODE_ERROR, [], '输入数据有误');
return sendMsg(response, JSON.stringify(data));
}
}
switch (urlPath) {
case '/':
var filePath = 'public/index.html';
var absPath = './' + filePath;
readFile(response, absPath);
break;
case '/query':
doQuery(response);
break;
case '/add':
doAdd(response, itemData);
break;
case '/complete':
doCompelete(response, itemData);
break;
}
});
server.listen(port, hostname, () => {
console.log(`Server running at http://${
hostname}:${
port}/`)
})
verify
Execute the command node server.js to start the project
add to-do
- 1111
- en1111
- Chinese 1111
complete to-do
- 1111
- en1111
- Chinese 1111
Check whether the data in the database meets expectations
project code address
Gitee code repository: https://gitee.com/3281328128/todo_list/tree/mysql/