ORM concept (Sequelize, Prisma overview) in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import Sequelize in a Node.js project.

Node.js

const Sequelize = require('[1]');

Drag options to blanks, or click blank then click option'

ASequelize

Bsequelize

Csequelizejs

DSequelizeJS

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase 'Sequelize' instead of lowercase 'sequelize'

Using incorrect package names like 'sequelizejs'

The npm package name for Sequelize is sequelize (lowercase).

2fill in blank

medium

Complete the code to initialize a Prisma client instance.

Node.js

const prisma = new [1]();

Drag options to blanks, or click blank then click option'

ASequelize

BPrisma

CClient

DPrismaClient

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Sequelize' instead of 'PrismaClient'

Using just 'Prisma' without 'Client'

To use Prisma, you create a new instance of PrismaClient.

3fill in blank

hard

Fix the error in this Sequelize model definition by completing the missing data type.

Node.js

const User = sequelize.define('User', {
  username: {
    type: Sequelize.[1],
    allowNull: false
  }
});

Drag options to blanks, or click blank then click option'

AStr

BText

CSTRING

Dstring

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or incorrect data type names

Using 'Text' instead of 'STRING'

Sequelize data types are uppercase constants like STRING.

4fill in blank

hard

Fill both blanks to write a Prisma query that finds all users with age greater than 18.

Node.js

const adults = await prisma.user.findMany({
  where: {
    age: { [1]: [2] }
  }
});

Drag options to blanks, or click blank then click option'

Agt

B18

Cgte

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'gte' instead of 'gt' for strictly greater than

Using a string '18' instead of number 18

In Prisma, gt means 'greater than'. We compare age to 18.

5fill in blank

hard

Fill all three blanks to create a Sequelize model with a 'title' string and 'published' boolean fields.

Node.js

const Post = sequelize.define('Post', {
  title: {
    type: Sequelize.[1],
    allowNull: false
  },
  published: {
    type: Sequelize.[2],
    defaultValue: [3]
  }
});

Drag options to blanks, or click blank then click option'

ASTRING

BBOOLEAN

Cfalse

DTRUE

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase data types

Setting defaultValue to TRUE instead of false

Use STRING for text and BOOLEAN for true/false. Default is false here.

Practice

1. What is the main purpose of an ORM like Sequelize or Prisma in Node.js?

easy

A. To simplify database operations by using JavaScript code instead of raw SQL

B. To replace Node.js as a runtime environment

C. To create user interfaces for web applications

D. To manage server hardware resources

Solution

1. Step 1: Understand what ORM stands for

   ORM means Object-Relational Mapping, which helps translate code into database queries.

2. Step 2: Identify ORM's role in Node.js

   Sequelize and Prisma let developers write JavaScript code to interact with databases instead of writing SQL directly.

3. Final Answer:

   To simplify database operations by using JavaScript code instead of raw SQL -> Option A

4. Quick Check:

   ORM = Simplify database code [OK]

Hint: ORM means code replaces SQL for easier database work [OK]

Common Mistakes:

• Thinking ORM replaces Node.js runtime
• Confusing ORM with UI tools
• Assuming ORM manages hardware

2. Which of the following is the correct way to define a model in Sequelize?

easy

A. createModel('User', { name: 'string' })

B. sequelize.define('User', { name: DataTypes.STRING })

C. new Model('User', { name: String })

D. Model.defineUser({ name: DataType.String })

Solution

1. Step 1: Recall Sequelize model definition syntax

   Sequelize uses sequelize.define(modelName, attributes) to create models.

2. Step 2: Match options with correct syntax

   sequelize.define('User', { name: DataTypes.STRING }) matches the correct method and uses DataTypes.STRING properly.

3. Final Answer:

   sequelize.define('User', { name: DataTypes.STRING }) -> Option B

4. Quick Check:

   Sequelize model = sequelize.define() [OK]

Hint: Sequelize models use sequelize.define() with DataTypes [OK]

Common Mistakes:

• Using 'new Model' instead of sequelize.define
• Incorrect DataTypes usage
• Wrong method names like createModel

3. Given this Prisma schema snippet:

model Post {
  id    Int     @id @default(autoincrement())
  title String
  published Boolean @default(false)
}

What will be the default value of published when a new Post is created without specifying it?

medium

A. false

B. true

C. null

D. undefined

Solution

1. Step 1: Read the Prisma model definition

   The field published is Boolean with @default(false), meaning it defaults to false.

2. Step 2: Understand default behavior on creation

   If no value is given for published, Prisma sets it to the default, which is false.

3. Final Answer:

   false -> Option A

4. Quick Check:

   Prisma default Boolean = false [OK]

Hint: Look for @default() in Prisma schema for default values [OK]

Common Mistakes:

• Assuming default is true without checking
• Thinking default is null or undefined
• Ignoring @default directive

4. You wrote this Sequelize code:

const User = sequelize.define('User', {
  username: Sequelize.STRING,
  age: Sequelize.INTEGER
});

But you get an error: Sequelize.STRING is not a constructor. What is the likely fix?

medium

A. Change Sequelize.STRING to 'string' (a string literal)

B. Remove the model definition and use raw SQL instead

C. Import DataTypes from Sequelize and use DataTypes.STRING instead

D. Rename 'User' to 'Users' in define method

Solution

1. Step 1: Identify the cause of the error

   Sequelize.STRING is not a constructor because Sequelize exports DataTypes separately.

2. Step 2: Correct usage of DataTypes

   You should import DataTypes from Sequelize and use DataTypes.STRING and DataTypes.INTEGER in model definitions.

3. Final Answer:

   Import DataTypes from Sequelize and use DataTypes.STRING instead -> Option C

4. Quick Check:

   Use DataTypes.STRING, not Sequelize.STRING [OK]

Hint: Use DataTypes from Sequelize for types, not Sequelize directly [OK]

Common Mistakes:

• Using Sequelize.STRING instead of DataTypes.STRING
• Trying to fix by renaming model
• Switching to raw SQL unnecessarily

5. You want to fetch all users with their posts using Prisma. Which code snippet correctly fetches users including their posts?

hard

A. const users = await prisma.user.findAll({ include: ['posts'] });

B. const users = await prisma.user.findMany({ select: { posts: false } });

C. const users = await prisma.user.findMany({ where: { posts: null } });

D. const users = await prisma.user.findMany({ include: { posts: true } });

Solution

1. Step 1: Recall Prisma syntax for including related models

   Prisma uses include: { relatedModel: true } to fetch related data.

2. Step 2: Check each option for correct syntax

   const users = await prisma.user.findMany({ include: { posts: true } }); uses include: { posts: true } which is correct. const users = await prisma.user.findMany({ select: { posts: false } }); excludes posts, C filters by posts null, D uses wrong method name.

3. Final Answer:

   const users = await prisma.user.findMany({ include: { posts: true } }); -> Option D

4. Quick Check:

   Prisma include related = include: { posts: true } [OK]

Hint: Use include: { relatedModel: true } to fetch relations in Prisma [OK]

Common Mistakes:

• Using findAll instead of findMany in Prisma
• Using select to exclude instead of include to fetch
• Wrong syntax for including relations