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02. Develop data storage of blog project

2022-07-06 05:18:00 【John is orange】

Develop data storage for blog projects

Premise ： install MySQL, And use graphical interface to facilitate operation （DBeaver、MySQL Workbench etc. ）

1. Database operation （ Create, add, delete, modify, and query ）

1.1 Creating databases and tables

It can be used SQL Statement writing , But it is simpler and less error prone to operate with a graphical interface .

Right click to create a database , The name is myblog.

Right click myblog, Create two tables :

Blog
user
The password needs to be encrypted

id It's the only sign , It's the primary key , And set it to automatically increase , After inserting data later , You don't need to add it yourself id.

1.2 Additions and deletions

Using a database myblog

use myblog;

see myblog All tables in

show tables;

Add data

INSERT INTO users (username, `password`, realname) VALUES ('admin', '123456', ' Administrators ');

Query data

Inquire about users All columns in ：

SELECT * FROM users;

Find data for a specific column , It can optimize query performance ：

SELECT id, username FROM users;

Query with query criteria , For example, the query user name is zhangsan Information about ：

SELECT * FROM users WHERE username = 'zhangsan';

and and or collocation , It has the same meaning as in programming

SELECT * FROM users WHERE username = 'zhangsan' AND password='123456';

SELECT * FROM users WHERE username = 'zhangsan' OR password='123456'

Fuzzy query , Such as query username Internal band zhang The data of

SELECT * FROM users WHERE username LIKE '%zhang%';

Sorting results （ Default positive order ）：

SELECT * FROM users WHERE password LIKE '%1%' ORDER BY id;

If you want to see the result in reverse order ：

SELECT * FROM users WHERE password LIKE '%1%' ORDER BY id DESC;

Update data

Be careful , When updating, you should mark the update conditions , Otherwise, all rows will be updated ！

UPDATE users SET realname = ' Li Si 2' WHERE username = 'lisi';

Delete data

alike , When deleting data, you should also mark the deletion conditions ！

DELETE FROM users WHERE username = 'lisi';

Generally, delete lines are not deleted in this way , But soft delete —— Update fields . There is a field in the table, such as state , The default value is 1. To mark whether it is deleted , If deleted, mark as 0, Otherwise 1. In this way, data recovery can be done well , Instead of permanently deleting .

UPDATE users SET state = 0 WHERE username = 'lisi';

2. nodejs operation MySQL

The data used before are all analog data , You can't use simulated data later , Rather let API To manipulate the database .

install MySQL Third party Library

yarn add mysql

Basic usage

const mysql = require("mysql");

//  Create connection objects 
const con = mysql.createConnection({
    
  host: "localhost",
  user: "root",
  password: "123456",
  port: "3306",
  database: "myblog",
});

//  Start connecting 
con.connect();

//  perform  SQL  sentence 
const sql = "SELECT * FROM users;";

con.query(sql, (err, result) => {
    
  if (err) {
    
    console.log(err);
    return;
  }
  console.log(result);
});

//  Close the connection 
con.end();

After inputting the necessary information, connect to the resume database , And then execute SQL sentence , And execute successful or failed callbacks .

The result of the above code output ：

[
  RowDataPacket {
    
    id: 1,
    username: 'admin',
    password: '123456',
    realname: ' Administrators '
  },
  RowDataPacket {
    
    id: 2,
    username: 'zhangsan',
    password: '123456',
    realname: ' Zhang San '
  },
  RowDataPacket {
    
    id: 4,
    username: 'lisi',
    password: '123456',
    realname: ' Li Si '
  }
]

If sql The statement is as follows ：

const sql = "UPDATE users SET realname = ' Li Si 2' WHERE username = 'lisi';";

The returned result is as follows ：

OkPacket {
    
  fieldCount: 0,
  affectedRows: 1,
  insertId: 0,
  serverStatus: 34,
  warningCount: 0,
  message: '(Rows matched: 1 Changed: 1 Warnings: 0',
  protocol41: true,
  changedRows: 1
}

The returned data has a lot of information . Including the corresponding id, The number of lines affected .

3. nodejs Connect MySQL Tool implementation

above nodejs The writing method of connecting and operating the database is quite laborious , The real core code is SQL Operation code , So we need to optimize .

Add a profile , Put the configuration required for connection inside ：

// conf/db.js

//  Get environment parameters 
const env = process.env.NODE_ENV;

let MYSQL_CONF = {
    };

//  The address of the database in the development environment 
if (env === "dev") {
    
  MYSQL_CONF = {
    
    host: "localhost",
    user: "root",
    password: "123456",
    port: "3306",
    database: "myblog",
  };
}

//  The address of the database in the production environment 
if (env === "production") {
    
  MYSQL_CONF = {
    
    host: "localhost",
    user: "root",
    password: "123456",
    port: "3306",
    database: "myblog",
  };
}

module.exports = {
    
  MYSQL_CONF,
};

Create unified execution sql Functions and related tools

sql The execution of is asynchronous , So with promise The package is the best .

const mysql = require("mysql");
const {
       MYSQL_CONF } = require("../conf/db");

//  Create connection objects 
const con = mysql.createConnection(MYSQL_CONF);

//  Start connecting 
con.connect();

//  Unified execution  SQL  Function of 
function exec(sql) {
      
  return new Promise((resolve, reject) => {
      
    con.query(sql, (err, result) => {
      
      if (err) {
      
        console.error(err);
        return;
      }
      resolve(result);
    });
  });
}

module.exports = {
      
  exec,
};

4. API docking MySQL（ Blog list ）

After writing as above , One thing to keep in mind is that , perform SQL Statement returns promise, So get then perhaps await Then we can get the data .

// router/blog.js
  //  Get a list of blogs 
  if (method === "GET" && req.path === "/api/blog/list") {
    
    const author = req.query.author || "";
    const keyword = req.query.keyword || "";
    const result = getList(author, keyword);
    //  return  promise
    return result.then((listData) => {
    
      return new SuccessModel(listData);
    });
  }

// controller/blog.js
const getList = (author, keyword) => {
    
  let sql = `select id, title, content, createtime, author from blogs where 1 = 1`;
  if (author) {
    
    sql += ` and author = '${
      author}'`;
  }
  if (keyword) {
    
    sql += ` and title like '%${
      keyword}%'`;
  }
  sql += ` order by createTime desc;`;

  return exec(sql);
};

5. API docking MySQL（ Blog list details ）

// router/blog.js
  //  Get blog details 
  if (method === "GET" && req.path === "/api/blog/detail") {
    
    const result = getDetail(id);
    return result.then((data) => {
    
      return new SuccessModel(data);
    });
  }

// controller/blog.js
const getDetail = (id) => {
    
  const sql = `select id, title, content, createTime, author from blogs where id = '${
      id}'`;
  return exec(sql).then((rows) => {
    
    //  It's an array , Extract the first item in the array 
    return rows[0];
  });
};

5. API docking MySQL （ New blog ）

// router/blog.js
  //  Create a new blog 
  if (method === "POST" && req.path === "/api/blog/new") {
    
    //  To create a new blog, you need to get  author, But now the login function is not finished , Not yet 
    req.body.author = "zhangssan";
    const result = newBlog(req.body);
    return result.then((data) => {
    
      return new SuccessModel(data);
    });
  }

// controller/blog.js
const newBlog = (blogData = {
     }) => {
    
  // blogData  Is a blog object , contain  title、content、author  attribute 
  blogData = {
    
    ...blogData,
    createTime: Date.now(),
    id: 3, //  Indicates a new blog , Inserted into the data table  id
  };
  const {
     title, content, author, createTime } = blogData;
  const sql = ` insert into blogs (title, content, createTime, author) values ('${
      title}', '${
      content}', ${
      createTime}, '${
      author}');`;
  return exec(sql).then((insertData) => {
    
    // promise  Returns the inserted value corresponding to  id
    return {
    
      id: insertData.insertId,
    };
  });
};

6. API docking MySQL（ Update blog ）

// router/blog.js
  //  Update a blog 
  if (method === "POST" && req.path === "/api/blog/update") {
    
    const result = updateBlog(id, req.body);
    return result.then((val) => {
    
      if (val) {
    
        return new SuccessModel();
      } else {
    
        return new ErrorModel(" Failed to update blog ");
      }
    });
  }

// controller/blog.js
const updateBlog = (id, blogData = {
     }) => {
    
  const {
     title, content } = blogData;
  const sql = ` update blogs set title = '${
      title}', content = '${
      content}' where id = ${
      id} `;
  return exec(sql).then((updatedData) => {
    
    if (updatedData.affectedRows > 0) {
    
      return true;
    }
    return false;
  });
};

7. API docking MySQL（ Delete blog ）

// router/blog.js
  //  Delete a blog 
  if (method === "POST" && req.path === "/api/blog/del") {
    
    //  Login function is not completed , First use false data 
    const author = "zhangsan";
    const result = delBlog(id, author);
    return result.then((val) => {
    
      if (val) {
    
        return new SuccessModel();
      } else {
    
        return new ErrorModel(" Failed to delete blog ");
      }
    });
  }

// controller/blog.js
const delBlog = (id, author) => {
    
  const sql = ` delete from blogs where id = '${
      id}' and author = '${
      author}'; `
  return  exec(sql).then((delData) => {
    
    if (delData.affectedRows > 0) {
    
      return true;
    }
    return false;
  });
};

8. API docking MySQL（ The user login ）

// controller/user.js
const loginCheck = (username, password) => {
    
  const sql = ` select username, realname from users where username = '${
      username}' and password = '${
      password}'; `;
  return exec(sql).then((rows) => {
    
    return rows[0] || {
    };
  });
};

// router/user.js
  //  Sign in 
  if (method === "POST" && req.path === "/api/user/login") {
    
    const {
     username, password } = req.body;
    const result = loginCheck(username, password);
    return result.then((data) => {
    
      if (data.username) {
    
        return new SuccessModel();
      }
      return new ErrorModel(" Login failed ");
    });
  }

Because of the above router It's all back promise, The previous false data is synchronized , therefore router The returned data needs to pass then perhaps await receive .

// app.js
const serverHandle = async (req, res) => {
    
  //  Set the return format  JSON
  res.setHeader("Content-type", "application/json");

  //  obtain  path
  const url = req.url;
  req.path = url.split("?")[0];
  
  //  analysis  query
  req.query = qs.parse(url.split("?")[1]);

  //  analysis  POST data  Put it after  req.body  Inside 
  const postData = await getPostData(req);
  req.body = postData;

  //  Handle  blog  route 
  const blogData = await handleBlogRouter(req, res);
  if (blogData) {
    
    res.end(JSON.stringify(blogData));
    //  Need to be  return, Otherwise, it will continue to execute 
    return;
  }

  //  Handle  user  route 
  const userData = await handleUserRouter(req, res);
  if (userData) {
    
    res.end(JSON.stringify(userData));
    return;
  }

  //  Missed route ： Plain text returns  404  Information 
  res.writeHead(404, {
     "content-type": "text/plain" });
  res.write("404 not found");
  res.end();
};