Example of Create

1. Let's create an endpoint to insert new user into the database, create create.js into directory controllers->users

2.  Write down using this code

const connection = require("../../services/database");

const create = async (req, res) => {
	// Get data from body
	const { username, password, email } = req.body;
	// Check if email is in the right format
	const checkEmail = new RegExp(
		/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/
	).test(email);
	// Return error if the input are null or the email is not in the right format
	if (!username || !password || !email || !checkEmail) {
		return res.json({
			success: false,
			data: null,
			error: "Invalid input",
		});
	}

	try {
		//Insert the data to the database
		const createUser = await connection
			.promise()
			.query(
				`INSERT INTO users (username, password, email) VALUES ('${username}', '${password}', '${email}')`
			);
		// Return success if the data is inserted
		return res.json({
			success: true,
			data: null,
			error: null,
		});
	} catch (error) {
		console.error("Error:", error);
		return res.status(500).json({
			success: false,
			data: null,
			error: error.message,
		});
	}
};
module.exports = create;

3. Go to user.js in directory routers and add the line below

const express = require("express");
const getAll = require("../controllers/users/getAll");
//add this line 👇
const create = require("../controllers/users/create");
const usersRouter = express.Router();

usersRouter.get("/all", getAll);
//add this line 👇
usersRouter.post("/create", create);

module.exports = usersRouter;

4. Let's run your application again, and use postman with  localhost:5000/users/create don't forget to change the HTTP METHOD GET to POST then send the username, password and email in body with JSON

• You will see the result like this.

****Remark - HTTP Methods 👇🏻

-END-

Example of the POST method

Create an endpoint that create a user

Before writing a request, we need to install the library body-parser first.

npm i body-parser

Because Express JS cannot read the JSON body request directly, So we need to install body-parser first.

const bodyParser = require("body-parser"); // import the body-parser

// parse various different custom JSON types as JSON
app.use(bodyParser.json({ type: "application/json" }));

Code ...

const express = require("express");
const app = express();
const mysql = require("mysql2");
const bodyParser = require("body-parser"); 👈🏻
const port = 3000;

const connection = mysql.createConnection({
  host: "server2.mixkoap.com",
  port: "6103",
  user: "root",
  password: "root_apisitmaneerat",
  database: "csc105-workshop",
});

// Connect to database
connection.connect();

console.log("Database is connected");

// parse various different custom JSON types as JSON
app.use(bodyParser.json({ type: "application/json" })); 👈🏻

app.get("/", (req, res) => {
  res.send("Hello World!");
});
.
.
.
.
.
.

Create an endpoint

app.post("/todo/create", (req, res) => {
  // The JSON body
  const payload = req.body;

  connection.query(
    `INSERT INTO users (username) VALUES (?)`, [payload.userName], (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        // Return data to the client if success
        console.log(rows);
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "create success",
            },
          });
        }
      }
    }
  );
});

The request body mostly send in JSON format 👆🏻 Create a request in Postman and change the HTTP method to POST

****Remark - HTTP Methods 👇🏻

Add the JSON body 👇🏻

http://127.0.0.1:3000/todo/create

{
    "userName" : "Apisit Maneerat"
}

Click Send

The response from your backend application. 👆🏻

In the Database 👇🏻

For more detail

Example of the PATCH method

Create an endpoint that edit the data in the Database

For example we are going to change the name and detail from id = 1

Create the endpoint For this endpoint we use .patch() because we are going to edit some fields that you specific in the Database.

app.patch("/todo/edit", (req, res) => {
  // The JSON body
  const payload = req.body;

  console.log(payload);

  connection.query(
    "UPDATE items SET name = ?, detail = ? WHERE id = ?", [payload.name, payload.detail, payload.id],
    (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        // Return data to the client if success
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "update successfully",
            },
          });
        }
      }
    }
  );
});

Create a request in Postman

Click Send

Example of the DELETE method

Create an endpoint that delete the data from the links table in the database.

For this endpoint, we will use .delete() because we are going to delete data from the database. We use query string to get the data from the client Create an endpoint 👇🏻

app.delete("/todo/delete", (req, res) => {
  // Assign the params as a variable
  const id = req.query.id;
  const todoId = req.query.todo_id;

  connection.query(
    `DELETE FROM links where id = ? AND todo_id = ?`, [id, todoId],
    (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "delete successfully",
            },
          });
        }
      }
    }
  );
});

Create a request in Postman

Click Send

--- End of the example ----

** This is the finalized code for this example 👇🏻

const express = require("express");
const app = express();
const mysql = require("mysql2");
const bodyParser = require("body-parser");
const port = 3000;

const connection = mysql.createConnection({
  host: "server2.mixkoap.com",
  port: "6103",
  user: "root",
  password: "root_apisitmaneerat",
  database: "csc105-workshop",
});

// Connect to database
connection.connect();

console.log("Database is connected");

// parse various different custom JSON types as JSON
app.use(bodyParser.json({ type: "application/json" }));

app.get("/", (req, res) => {
  res.send("Hello World!");
});

app.get("/hello", (req, res) => {
  res.json({
    name: "Apisit Maneerat",
    nickName: "Mixko",
    university: "KMUTT",
  });
});

app.get("/todo/all", (req, res) => {
  connection.query("SELECT * FROM items", (err, rows) => {
    // Check if cannot find the data in the database then return the error
    if (err) {
      res.json({
        success: false,
        data: null,
        error: err.message,
      });
    } else {
      // Return data to the client if success
      res.json({
        success: true,
        data: rows,
        error: null,
      });
    }
  });
});

app.get("/todo", (req, res) => {
  // Assign the params as a variable
  // https://medium.com/@joseph.pyram/9-parts-of-a-url-that-you-should-know-89fea8e11713
  const todoId = req.query.todo_id;

  // Regex to check the todo_is is a number only or not
  const checkTodoId = new RegExp(/^\d+$/).test(todoId); // Boolean

  // Check if the todo_id is not exist or is not a number, return json with an error
  if (!todoId || !checkTodoId) {
    res.json({
      success: false,
      data: null,
      error: "todo_id is invalid",
    });
  }

  connection.query(`SELECT * FROM items WHERE id = ${todoId}`, (err, rows) => {
    // Check if cannot find the data in the database then return the error
    if (err) {
      res.json({
        success: false,
        data: null,
        error: `Data not found ${err.message}`,
      });
    } else {
      // Return data to the client if success
      if (rows[0]) {
        res.json({
          success: true,
          data: rows[0],
          error: null,
        });
      } else {
        res.json({
          success: true,
          data: null,
          error: null,
        });
      }
    }
  });
});

app.post("/todo/create", (req, res) => {
  // The JSON body
  const payload = req.body;

  connection.query(
    `INSERT INTO users (username) VALUES (?)`,
    [payload.userName],
    (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        // Return data to the client if success
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "create successfully",
            },
          });
        }
      }
    }
  );
});

app.patch("/todo/edit", (req, res) => {
  // The JSON body
  const payload = req.body;

  console.log(payload);

  connection.query(
    "UPDATE items SET name = ?, detail = ? WHERE id = ?",
    [payload.name, payload.detail, payload.id],
    (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        // Return data to the client if success
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "update successfully",
            },
          });
        }
      }
    }
  );
});

app.delete("/todo/delete", (req, res) => {
  // Assign the params as a variable
  const id = req.query.id;
  const todoId = req.query.todo_id;

  connection.query(
    `DELETE FROM links where id = ? AND todo_id = ?`,
    [id, todoId],
    (err, rows) => {
      // Check if cannot find the data in the database then return the error
      if (err) {
        return res.json({
          success: false,
          data: null,
          error: err.message,
        });
      } else {
        if (rows) {
          res.json({
            success: true,
            data: {
              message: "delete successfully",
            },
          });
        }
      }
    }
  );
});

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});

More examples for those who want to create more than one query in one endpoint

app.get("/todo/from", async (req, res) => {
  const userId = req.query.userId;

  // User data
  const userData = await new Promise((resolve, reject) => {
    connection.query(
      `SELECT * FROM users WHERE id = ?`,
      [userId],
      (err, rows) => {
        if (err) {
          res.json({
            suceess: false,
            error: err.message,
          });
        } else {
          resolve(rows[0]);
        }
      }
    );
  });

  // User's todos
  const userTodos = await new Promise((resolve, reject) => {
    connection.query(
      `SELECT * FROM items WHERE owner_id = ?`,
      [userId],
      (err, rows) => {
        if (err) {
          res.json({
            suceess: false,
            error: err.message,
          });
        } else {
          resolve(rows);
        }
      }
    );
  });

  res.json({
    success: true,
    data: {
      user_data: userData,
      todos: userTodos,
    },
    error: null,
  });
});