CRUD operations with Prisma in NextJS - Mini Project: Build & Apply

CRUD operations with Prisma

📖 Scenario: You are building a simple Next.js app to manage a list of books in a library. You will use Prisma to connect to a database and perform CRUD (Create, Read, Update, Delete) operations on the books.

🎯 Goal: Build a Next.js API route that uses Prisma to create, read, update, and delete books in the database.

📋 What You'll Learn

Create a Prisma client instance

Define a book data object with title and author

Write a function to create a new book in the database

Write a function to read all books from the database

Write a function to update a book's title by ID

Write a function to delete a book by ID

💡 Why This Matters

🌍 Real World

Managing data in web applications is common. Prisma helps connect your Next.js app to a database and perform CRUD operations easily.

💼 Career

Many web developer roles require working with databases and APIs. Knowing Prisma with Next.js is a valuable skill for building modern full-stack apps.

1

Set up Prisma client

Import PrismaClient from '@prisma/client' and create a constant called prisma that is a new PrismaClient instance.

NextJS

import { PrismaClient } from '@prisma/client'

// Create Prisma client instance
// Your code here

Hint

Use import { PrismaClient } from '@prisma/client' and then const prisma = new PrismaClient().

2

Create a book data object

Create a constant called newBook that is an object with title set to 'The Great Gatsby' and author set to 'F. Scott Fitzgerald'.

NextJS

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient()

// Create a book data object
// Your code here

Hint

Define newBook as an object with the exact keys and values.

3

Write a function to create a book

Write an async function called createBook that uses prisma.book.create with data: newBook and returns the created book.

NextJS

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient()

const newBook = { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' }

// Write async function createBook
// Your code here

Hint

Use async function createBook() and inside use await prisma.book.create({ data: newBook }).

4

Add read, update, and delete functions

Add three async functions: getBooks that returns all books using prisma.book.findMany(), updateBookTitle that takes id and newTitle and updates the book title using prisma.book.update, and deleteBook that takes id and deletes the book using prisma.book.delete.

NextJS

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient()

const newBook = { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' }

async function createBook() {
    const book = await prisma.book.create({ data: newBook })
    return book
}

// Add async functions getBooks, updateBookTitle, and deleteBook
// Your code here

Hint

Write three async functions using Prisma client methods: findMany, update, and delete.

Practice

1. What does the prisma.user.create() method do in Next.js with Prisma?

easy

A. It adds a new user record to the database.

B. It fetches all user records from the database.

C. It updates an existing user record.

D. It deletes a user record from the database.

Solution

1. Step 1: Understand the method name

   The method create() is used to add new data in Prisma.

2. Step 2: Match method to CRUD operation

   Creating means adding new records, so prisma.user.create() adds a new user.

3. Final Answer:

   It adds a new user record to the database. -> Option A

4. Quick Check:

   Create method = Add new record [OK]

Hint: Create method adds new data, not read or delete [OK]

Common Mistakes:

• Confusing create() with findMany() which reads data
• Thinking create() updates existing records
• Assuming create() deletes records

2. Which of the following is the correct syntax to update a user with id 5 using Prisma in Next.js?

easy

A. prisma.user.edit({ where: { id: 5 }, data: { name: 'Alice' } })

B. prisma.user.modify({ id: 5, name: 'Alice' })

C. prisma.user.update({ where: { id: 5 }, data: { name: 'Alice' } })

D. prisma.user.change({ id: 5, data: { name: 'Alice' } })

Solution

1. Step 1: Identify Prisma update syntax

   Prisma uses update() with where and data keys to update records.

2. Step 2: Check option correctness

   Only prisma.user.update({ where: { id: 5 }, data: { name: 'Alice' } }) uses correct method update() and proper keys where and data.

3. Final Answer:

   prisma.user.update({ where: { id: 5 }, data: { name: 'Alice' } }) -> Option C

4. Quick Check:

   Update method uses where and data keys [OK]

Hint: Update uses update({ where, data }) syntax [OK]

Common Mistakes:

• Using non-existent methods like modify(), change(), edit()
• Missing where or data keys in update()
• Passing id directly without where object

3. Given this code snippet in Next.js with Prisma:

const users = await prisma.user.findMany({ where: { active: true } });
console.log(users.length);

What will console.log(users.length) output?

medium

A. Always 0, because findMany returns undefined.

B. The total number of users, active or not.

C. An error because findMany needs data key.

D. The number of active users in the database.

Solution

1. Step 1: Understand findMany with where filter

   The findMany() method returns an array of records matching the where condition.

2. Step 2: Analyze the filter condition

   Only users with active: true are returned, so users.length is count of active users.

3. Final Answer:

   The number of active users in the database. -> Option D

4. Quick Check:

   findMany with where returns filtered array [OK]

Hint: findMany returns array; length counts filtered records [OK]

Common Mistakes:

• Thinking findMany returns undefined or error
• Ignoring the where filter effect
• Assuming it returns all users without filter

4. Identify the error in this Prisma delete operation:

await prisma.user.delete({ id: 10 });

medium

A. Missing the 'where' key wrapping the id.

B. Using delete() instead of remove().

C. id should be a string, not a number.

D. delete() cannot be used with await.

Solution

1. Step 1: Check delete() method syntax

   Prisma's delete() requires an object with a where key specifying the record to delete.

2. Step 2: Identify missing where key

   The code passes { id: 10 } directly, missing where: { id: 10 }.

3. Final Answer:

   Missing the 'where' key wrapping the id. -> Option A

4. Quick Check:

   Delete needs where key with id [OK]

Hint: Delete needs where: { id } object, not just id [OK]

Common Mistakes:

• Omitting where key in delete()
• Using remove() which does not exist in Prisma
• Thinking id type must be string always
• Believing delete() can't be awaited

5. You want to update a user's email only if the user exists, otherwise create a new user with that email. Which Prisma method best fits this use case in Next.js?

hard

A. prisma.user.create({ data: { email } })

B. prisma.user.upsert({ where: { email }, update: { email }, create: { email } })

C. prisma.user.update({ where: { email }, data: { email } })

D. prisma.user.findUnique({ where: { email } })

Solution

1. Step 1: Understand the upsert method

   Upsert updates if record exists, else creates new one in Prisma.

2. Step 2: Match use case to method

   Since we want to update or create based on existence, upsert() fits perfectly.

3. Final Answer:

   prisma.user.upsert({ where: { email }, update: { email }, create: { email } }) -> Option B

4. Quick Check:

   Upsert = update or create [OK]

Hint: Use upsert to update or create in one call [OK]

Common Mistakes:

• Using update() alone which fails if user missing
• Using create() alone which fails if user exists
• Using findUnique() which only reads data