Cache decorators in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @Cacheable() decorator in NestJS?

The @Cacheable() decorator marks a method so that its result is stored in cache. When the method is called again with the same arguments, the cached result is returned instead of running the method again, improving performance.

intermediate

How does the @CacheEvict() decorator work in NestJS?

The @CacheEvict() decorator is used to remove specific cache entries when a method is called. This helps keep the cache updated by deleting stale data after changes like updates or deletes.

intermediate

Explain the role of the @CachePut() decorator in NestJS.

The @CachePut() decorator updates the cache with the method's result every time the method is called, regardless of whether the cache already has a value. It is useful for refreshing cache data.

beginner

What is the default cache store used by NestJS cache decorators?

By default, NestJS uses an in-memory cache store for caching. This means cached data is stored in the server's memory and is lost when the server restarts.

intermediate

Why is it important to use cache decorators with proper cache keys?

Proper cache keys ensure that cached data is correctly identified and retrieved. Without unique keys, different method calls might overwrite each other's cache or return wrong data.

Which NestJS cache decorator stores the method result only if it is not already cached?

A @Cacheable()

B @CacheEvict()

C @CachePut()

D @CacheClear()

@Cacheable() caches the result only if it is not already cached. @CachePut() always updates the cache.

What does the @CacheEvict() decorator do?

A Updates cache without checking

B Stores method result in cache

C Removes cache entries

D Disables caching for a method

@CacheEvict() removes cache entries to keep cache data fresh.

If you want to refresh cache data every time a method runs, which decorator should you use?

A @CachePut()

B @CacheEvict()

C @Cacheable()

D @CacheDisable()

@CachePut() updates the cache every time the method is called.

What happens to the default in-memory cache when the NestJS server restarts?

A Cache persists on disk

B Cache is cleared

C Cache is backed up automatically

D Cache is sent to clients

In-memory cache is lost when the server restarts.

Why should cache keys be unique for different method calls?

A To speed up method execution

B To encrypt cached data

C To disable caching

D To prevent cache overwriting

Unique keys prevent different cached results from overwriting each other.

Describe how you would use cache decorators in NestJS to improve performance of a data fetching method.

Think about storing, updating, and clearing cache for data methods.

Explain the difference between @Cacheable(), @CachePut(), and @CacheEvict() decorators in NestJS.

Focus on when each decorator affects the cache.