Redis integration for distributed cache in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Redis client library.

Express

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

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

Aredis

Bexpress

Chttp

Dfs

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'express' or other unrelated packages instead of 'redis'.

Forgetting to install the redis package before importing.

The Redis client library is imported using require('redis') in Express apps.

2fill in blank

medium

Complete the code to create a Redis client instance.

Express

const client = redis.createClient({ url: '[1]' });

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

Ahttp://localhost:6379

Bftp://localhost:6379

Credis://localhost:6379

Dlocalhost:6379

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'http://' instead of 'redis://'.

Omitting the protocol prefix entirely.

The Redis client connects using a URL starting with redis:// followed by the host and port.

3fill in blank

hard

Fix the error in the code to connect the Redis client asynchronously.

Express

await client.[1]();

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Aconnect

Bstart

Copen

Dinit

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like 'start' or 'open'.

Not awaiting the asynchronous connect call.

The Redis client uses connect() method to establish the connection asynchronously.

4fill in blank

hard

Fill both blanks to set a key with expiration in Redis.

Express

await client.[1]('user:123', 'John Doe', { EX: [2] });

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

Aset

B3600

Cdel

Dexpire

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' or 'del' instead of 'set' to store data.

Confusing expiration time with milliseconds or other units.

Use set to store a key with a value and expiration time in seconds. The option EX sets the expiration.

5fill in blank

hard

Fill all three blanks to retrieve a cached value and handle missing keys.

Express

const value = await client.[1]('user:123');
if (value === [2]) {
  console.log([3]);
}

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

Aset

Bget

Cnull

D'Cache miss'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' instead of 'get' to retrieve data.

Checking for undefined instead of null.

Not handling the cache miss case.

Use get to retrieve a value. If the key does not exist, Redis returns null. We can log a message like 'Cache miss' to handle this case.