Cache drivers (file, Redis, Memcached) in Laravel - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set a cache value using the file driver.

Laravel

Cache::store('[1]')->put('key', 'value', 600);

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

Aredis

Bfile

Cmemcached

Ddatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'redis' or 'memcached' without having those services configured.

Confusing 'database' driver with file driver.

The file driver stores cache data in files on disk. This is the default simple cache driver in Laravel.

2fill in blank

medium

Complete the code to retrieve a cached value from Redis driver.

Laravel

$value = Cache::store('[1]')->get('key');

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

Aredis

Bfile

Cmemcached

Darray

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'file' driver name when intending to use Redis.

Using 'array' driver which is not persistent.

The redis driver connects to a Redis server to store and retrieve cache data.

3fill in blank

hard

Fix the error in the code to use Memcached driver for caching.

Laravel

Cache::store('[1]')->put('session', $data, 3600);

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

Aredis

Bfile

Cmemcached

Ddatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'memcache' instead of 'memcached'.

Using 'redis' or 'file' driver names by mistake.

The memcached driver uses Memcached service for caching. The driver name must be exactly 'memcached'.

4fill in blank

hard

Fill both blanks to create a cache key with prefix and set it using Redis driver.

Laravel

Cache::store('[1]')->put('[2]_user', $userData, 120);

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

Aredis

Bfile

Csession

Dmemcached

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'file' driver with Redis key prefix.

Using wrong prefixes that do not match the cache purpose.

The Redis driver is used for caching with Redis. The key prefix 'session' is often used to group related cache keys.

5fill in blank

hard

Fill all three blanks to retrieve a cached value with fallback using Memcached driver.

Laravel

$value = Cache::store('[1]')->remember('[2]', 300, function() { return [3]; });

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

Amemcached

Buser_profile

CUser::find(1)

Dredis

Attempts:

3 left

💡 Hint

Common Mistakes

Using Redis driver name instead of Memcached.

Using invalid cache keys or missing fallback function.

The remember method tries to get the cache value or runs the callback to store and return it. Using Memcached driver with a key and a fallback function is common.

Practice

1. Which Laravel cache driver stores cached data as files on the local server?

easy

A. memcached

B. file

C. redis

D. database

Solution

1. Step 1: Understand cache driver types in Laravel

   Laravel supports multiple cache drivers like file, redis, memcached, and database.

2. Step 2: Identify the driver that uses local files

   The 'file' driver stores cache data as files on the local server's disk.

3. Final Answer:

   file -> Option B

4. Quick Check:

   Local file storage = file [OK]

Hint: File driver means cache saved as local files [OK]

Common Mistakes:

• Confusing Redis or Memcached as file storage
• Thinking database driver stores files
• Assuming 'file' driver is remote cache

2. Which is the correct way to set Redis as the cache driver in Laravel's config/cache.php file?

easy

A. 'default' => 'redis',

B. 'driver' => 'redis',

C. 'cache_driver' => 'redis',

D. 'cache' => 'redis',

Solution

1. Step 1: Locate the cache driver setting in config/cache.php

   The main cache driver is set by the 'default' key in the config array.

2. Step 2: Confirm correct syntax for Redis driver

   Setting 'default' => 'redis' tells Laravel to use Redis as the cache driver.

3. Final Answer:

   'default' => 'redis' -> Option A

4. Quick Check:

   Default key sets cache driver = 'default' [OK]

Hint: Set 'default' key to driver name in config/cache.php [OK]

Common Mistakes:

• Using 'driver' instead of 'default' key
• Writing 'cache_driver' which is invalid
• Confusing config keys with environment variables

3. Given this Laravel code snippet using Redis cache driver:

Cache::put('user_1', 'Alice', 3600);
$name = Cache::get('user_1');

What will be the value of $name immediately after this code runs?

medium

A. "Alice"

B. null

C. "user_1"

D. 3600

Solution

1. Step 1: Understand Cache::put usage

   Cache::put stores the value 'Alice' with key 'user_1' for 3600 seconds (1 hour).

2. Step 2: Retrieve cached value with Cache::get

   Cache::get('user_1') returns the stored value 'Alice' if it exists and is not expired.

3. Final Answer:

   "Alice" -> Option A

4. Quick Check:

   Cache get returns stored value = "Alice" [OK]

Hint: Cache::get returns stored value if not expired [OK]

Common Mistakes:

• Expecting key name instead of value
• Confusing expiration time as returned value
• Assuming null because of Redis driver

4. What is wrong with this Laravel cache configuration snippet for Memcached in config/cache.php?

'memcached' => [
    'driver' => 'memcached',
    'servers' => [
        ['host' => '127.0.0.1', 'port' => 11211],
    ],
],

Why might this cause an error?

medium

A. Driver name should be 'memcache' not 'memcached'

B. Port number 11211 is incorrect for Memcached

C. Missing 'weight' key in the server array

D. Host IP must be 'localhost' not '127.0.0.1'

Solution

1. Step 1: Check Memcached server config requirements

   Laravel expects each Memcached server array to include 'host', 'port', and 'weight' keys.

2. Step 2: Identify missing 'weight' key

   The given config lacks the 'weight' key, which can cause errors when connecting to Memcached.

3. Final Answer:

   Missing 'weight' key in the server array -> Option C

4. Quick Check:

   Memcached servers need 'weight' key [OK]

Hint: Memcached server config must include 'weight' [OK]

Common Mistakes:

• Assuming port 11211 is wrong (it's default)
• Confusing driver name with 'memcache'
• Thinking host IP must be 'localhost'

5. You want to cache user profile data using Redis in Laravel, but only for 10 minutes. Which code snippet correctly sets this with expiration?

hard

A. Cache::put('profile_123', $profileData, 600);

B. Cache::put('profile_123', $profileData, now()->addSeconds(300));

C. Cache::put('profile_123', $profileData, 5);

D. Cache::put('profile_123', $profileData, now()->addMinutes(10));

Solution

1. Step 1: Understand Cache::put expiration parameter

   Laravel's Cache::put accepts expiration as an integer number of minutes, or a Carbon/DateTime instance.

2. Step 2: Use now()->addMinutes(10) for 10 minutes expiration

   Passing now()->addMinutes(10) sets expiration 10 minutes from current time correctly.

3. Step 3: Analyze other options

   A uses 600 (600 minutes = 10 hours), too long; C uses 5 minutes, too short; D uses now()->addSeconds(300) (5 minutes), too short.

4. Final Answer:

   Cache::put('profile_123', $profileData, now()->addMinutes(10)); -> Option D

5. Quick Check:

   Use now()->addMinutes(10) for 10 min cache [OK]

Hint: Use now()->addMinutes(10) for 10-minute cache expiration [OK]

Common Mistakes:

• Using 600 which is 600 minutes (10 hours)
• Using small integer 5 (5 minutes)
• Using addSeconds(300) which is 5 minutes