Example of Update

Let's create an endpoint to update user balance into the database, create updateBalance.js into directory controllers->transactions

2. Write down using this code

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

const updateBalance = async (req, res) => {
	const { userId, amount } = req.body;
	// Check if userId and amount is number or not
	const checkUserId = new RegExp(/^\d+$/).test(userId);
	const checkAmount = new RegExp(/^\d+$/).test(amount);
	// Return error if the userId and amount are null or it's not a number
	if (!userId || !checkUserId || !amount || !checkAmount) {
		return res.json({
			success: false,
			data: null,
			error: "Invalid input",
		});
	}
	// Update the balance
	try {
		await connection
			.promise()
			.query(`UPDATE users SET balance = ${amount} WHERE id = ${userId}`);
		// Return success if balance is upadated
		return res.json({
			success: true,
			data: null,
			error: null,
		});
	} catch {
		console.error("Error:", error);
		return res.status(500).json({
			success: false,
			data: null,
			error: error.message,
		});
	}
};
module.exports = updateBalance;

3. Go to transaction.js in directory routers and add the line below, this time we will use patch() since we want to update a single value.

const express = require("express");
const getBalance = require("../controllers/transactions/getBalance");
//add this line 👇
const updateBalance = require("../controllers/transactions/updateBalance");
const transactionsRouter = express.Router();

transactionsRouter.get("/balance", getBalance);
//add this line 👇
transactionsRouter.patch("/update", updateBalance);

module.exports = transactionsRouter;

4. Let's run your application again, and use postman with localhost:5000/transactions/update don't forget to change the HTTP METHOD POST,GET to PATCH then send the userId and the amount that we want to change it to in body with JSON

//example of JSON that we will be sending in the body
{   
	"userId":"1"
    "amount":"50000"
}

You will see the result like this.

-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,
  });
});

Example of Update

Example of the PATCH method

Example of the DELETE method

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

Example of the `PATCH` method

Example of the `DELETE` method