An example type-safe API with Node.js, Express.js, Prisma, and Joi that uses MySQL.

prisma-joi-express-api.js

/** Required Node.js modules */
const Express = require('express');
const Joi = require('joi')
const joiMiddleware = require('express-joi-validation').createValidator({})
const Prisma = require('prisma/prisma-client');
/** Instantiate Prisma client */
const prisma = new Prisma.PrismaClient();
 
/** Supplier validation schema for Joi */
const supplierSchema = Joi.object({
 id: Joi.number().greater(0),
 name: Joi.string().alphanum().min(1).max(191),
 contact: Joi.string().alphanum().min(1).max(191),
 email: Joi.string().email().max(191),
 phone_num: Joi.string().length(10).pattern(/^[0-9]+$/),
 address: Joi.string().alphanum().min(1).max(191),
});
/** Initialize Express */
const app = Express();
app.use(Express.json());
const port = 3000;
/** Routes */
app.get('/', (req, res) => {
 res.send("Hello, API server!");
});
 
/** Create a new supplier and write it to MySQL */
app.post("/supplier/create", joiMiddleware.query(supplierSchema), async (req, res) => {
  try {
    /** Use Prisma to write the data to our MySQL database */
    res.body = await prisma.supplier.create({
       data: {
          name: req.body.name,
          contact: req.body.contact,
          email: req.body.email,
          phone_num: req.body.phone_num,
          address: req.body.address,
       }
     });
     /** Send a response telling the user our data has been written */
     res.status(200).send({"message": "OK"});
  }
  /** If Prisma fails to write to the MySQL database */
  /** Catch the error and send it as our response */
  catch (err) {
    res.status(500).send(err);
  }
});
 
/** Get a supplier by name, return the object in our response */
app.get('/supplier', async (req, res) => {
  try {
   const supplier = await prisma.supplier.findUnique({
     where: {
       name: req.body.name,
       }
     });
     /** Send the Supplier object as our response */
     res.status(200).send({"object": supplier});
  }
  /** When Prisma fails to read from database, catch the error and send it as our response */
  catch (err) {
     res.status(500).send(err);
  }
});
 
/** Update an existing supplier */
app.patch("/supplier/update", joiMiddleware.query(supplierSchema), async (req, res) => {
  try {
    /** Use Prisma to write the data to our MySQL database */
    await prisma.supplier.update({
      where: {
         id: req.body.id,
      },
      data: {
        name: req.body.name,
        contact: req.body.contact,
        email: req.body.email,
        phone_num: req.body.phone_num,
        address: req.body.address,
      }
    });
    /** Send a response telling the user our data has been written */
    res.status(200).send({"message": "OK"});
  }
  /** When Prisma fails to write to database, catch the error and send it as response */
  catch (err) {
    res.status(500).send(err);
  }
});
 
/** Delete a supplier with a given name */
app.delete('/supplier/delete', joiMiddleware.query(supplierSchema), async (req, res) => {
  try {
    const supplier = await prisma.supplier.delete({
      where: {
        name: req.body.name,
      }
    });
    res.status(200).send({"message": "deleted OK"});
  }
  /** If Prisma fails to delete the object, catch the error and send it as response */
  catch (err) {
    res.status(500).send(err);
  }
});
 
/** Server */
app.listen(port, () => {
console.log(`API listening on localhost: ${port}`);
});

The prisma/schema.prisma file contents:

datasource db {
  provider = "mysql"
  url      = env("DATABASE_URL")
}

generator client {
  provider = "prisma-client-js"
}

model Supplier {
 id        Int    @id @default(autoincrement())
 name      String @unique
 contact   String
 email     String
 phone_num String
 address   String
}