CacheModule setup in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import CacheModule in a NestJS module.

NestJS

import { Module, [1] } from '@nestjs/common';
import { CacheModule } from '@nestjs/cache-manager';

@Module({
  imports: [CacheModule.register()],
})
export class AppModule {}

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

ACacheModule

BInjectable

CController

DModule

Attempts:

3 left

💡 Hint

Common Mistakes

Importing CacheModule instead of Module

Forgetting to import any decorator

Importing Injectable or Controller by mistake

The Module decorator is imported from @nestjs/common to define a NestJS module.

2fill in blank

medium

Complete the code to register CacheModule with a TTL of 5 seconds.

NestJS

CacheModule.register({ ttl: [1] })

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

A5

B5000

C60

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using milliseconds instead of seconds

Setting TTL to 0 which disables caching

Using a very large number unintentionally

The ttl option expects seconds, so 5 means cache expires after 5 seconds.

3fill in blank

hard

Fix the error in the CacheModule import statement.

NestJS

import { CacheModule } from '[1]';

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

A@nestjs/common

Bcache-manager

C@nestjs/cache-manager

D@nestjs/cache

Attempts:

3 left

💡 Hint

Common Mistakes

Importing from @nestjs/common

Importing from a non-existent package

Using 'cache-manager' directly

The correct package to import CacheModule from is @nestjs/cache-manager.

4fill in blank

hard

Fill both blanks to configure CacheModule with a max cache size of 100 and TTL of 10 seconds.

NestJS

CacheModule.register({ ttl: [1], max: [2] })

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

A10

B100

C5

D50

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up TTL and max values

Using too large or zero values

Omitting one of the options

TTL is set to 10 seconds and max cache size is set to 100 items.

5fill in blank

hard

Fill all three blanks to import CacheModule, register it with TTL 20, and export it from the module.

NestJS

import { Module, [1] } from '@nestjs/common';
import { CacheModule } from '[2]';

@Module({
  imports: [CacheModule.register({ ttl: [3] })],
  exports: [CacheModule],
})
export class CacheConfigModule {}

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

AModule

B@nestjs/cache-manager

C20

DInjectable

Attempts:

3 left

💡 Hint

Common Mistakes

Importing wrong decorators

Wrong package for CacheModule

Setting TTL to string instead of number

You import Module decorator, import CacheModule from @nestjs/cache-manager, and set TTL to 20 seconds.

Practice

1. What is the main purpose of importing CacheModule in a NestJS application?

easy

A. To enable temporary storage of data to speed up responses

B. To connect to a database automatically

C. To handle user authentication

D. To manage application logging

Solution

1. Step 1: Understand CacheModule's role

   CacheModule is used to store data temporarily to reduce repeated processing.

2. Step 2: Compare with other options

   It does not handle database, authentication, or logging directly.

3. Final Answer:

   To enable temporary storage of data to speed up responses -> Option A

4. Quick Check:

   CacheModule = temporary data storage [OK]

Hint: CacheModule is about caching data, not databases or auth [OK]

Common Mistakes:

• Confusing CacheModule with database modules
• Thinking CacheModule manages authentication
• Assuming CacheModule handles logging

2. Which of the following is the correct way to import and register CacheModule with a TTL of 5 seconds in a NestJS module?

easy

A. CacheModule.register({ ttl: 5 })

B. CacheModule.forRoot({ ttl: 5 })

C. CacheModule.setup({ ttl: 5 })

D. CacheModule.init({ ttl: 5 })

Solution

1. Step 1: Recall CacheModule registration method

   CacheModule uses the static method register to configure options like ttl.

2. Step 2: Verify method names

   Methods like forRoot, setup, or init are not used by CacheModule.

3. Final Answer:

   CacheModule.register({ ttl: 5 }) -> Option A

4. Quick Check:

   Use register() to configure CacheModule [OK]

Hint: CacheModule uses register(), not forRoot() or init() [OK]

Common Mistakes:

• Using forRoot() instead of register()
• Using setup() or init() which do not exist
• Forgetting to pass options inside register()

3. Given this NestJS module setup:

import { CacheModule, Module } from '@nestjs/common';

@Module({
  imports: [CacheModule.register({ ttl: 10 })],
})
export class AppModule {}

What will be the effect of the ttl: 10 option?

medium

A. Cache entries expire after 10 minutes

B. Cache entries expire after 10 seconds

C. Cache entries never expire

D. Cache entries expire immediately

Solution

1. Step 1: Understand ttl meaning in CacheModule

   The ttl option sets the time-to-live in seconds for cached data.

2. Step 2: Interpret ttl: 10

   Since ttl is 10, cached data expires after 10 seconds.

3. Final Answer:

   Cache entries expire after 10 seconds -> Option B

4. Quick Check:

   ttl = seconds cache lives [OK]

Hint: ttl value is in seconds, not minutes [OK]

Common Mistakes:

• Assuming ttl is in minutes
• Thinking ttl disables expiration
• Confusing ttl with cache size

4. Identify the error in this CacheModule setup:

import { CacheModule, Module } from '@nestjs/common';

@Module({
  imports: [CacheModule.register({ ttl: '20' })],
})
export class AppModule {}

medium

A. register() method does not accept options

B. CacheModule cannot be imported from '@nestjs/common'

C. ttl should be a number, not a string

D. Module decorator is missing parentheses

Solution

1. Step 1: Check ttl option type

   ttl expects a number representing seconds, not a string.

2. Step 2: Verify other parts

   CacheModule import and Module decorator usage are correct; register() accepts options.

3. Final Answer:

   ttl should be a number, not a string -> Option C

4. Quick Check:

   ttl must be numeric [OK]

Hint: ttl must be a number, not quoted text [OK]

Common Mistakes:

• Passing ttl as a string instead of number
• Thinking register() has no parameters
• Misusing import paths

5. You want to cache HTTP GET responses in a NestJS controller using CacheModule with a global TTL of 15 seconds. Which setup correctly applies caching to all routes in the module?

hard

A. Import CacheModule with ttl 15 and manually store cache in each method

B. Import CacheModule with ttl 15 and add @Cacheable() decorator on each method

C. Import CacheModule with ttl 15 and add @Cache() decorator on the module

D. Import CacheModule with ttl 15 and add @UseInterceptors(CacheInterceptor) on the controller

Solution

1. Step 1: Understand CacheModule and CacheInterceptor usage

   CacheModule provides caching, and CacheInterceptor applies caching behavior to routes.

2. Step 2: Apply CacheInterceptor globally on controller

   Using @UseInterceptors(CacheInterceptor) on the controller enables caching for all its routes.

3. Step 3: Evaluate other options

   No @Cacheable() or @Cache() decorators exist in NestJS core; manual caching is possible but not automatic.

4. Final Answer:

   Import CacheModule with ttl 15 and add @UseInterceptors(CacheInterceptor) on the controller -> Option D

5. Quick Check:

   Use CacheInterceptor with CacheModule for route caching [OK]

Hint: Use CacheInterceptor decorator to enable caching on controllers [OK]

Common Mistakes:

• Using non-existent decorators like @Cacheable or @Cache
• Not applying CacheInterceptor to controller or routes
• Trying manual caching instead of interceptor