Cache drivers (file, Redis, Memcached) in Laravel

Introduction

Cache drivers help store data temporarily to make your app faster. They save information so your app doesn't have to do the same work again and again.

When you want to speed up loading pages by saving data that doesn't change often.

When you want to reduce database queries by storing query results temporarily.

When you want to share cached data between multiple servers using Redis or Memcached.

When you want to store session data quickly and efficiently.

When you want to cache API responses to avoid repeated calls.

Syntax

Laravel

Cache::driver('driver_name')->put('key', 'value', now()->addSeconds($seconds));
Cache::driver('driver_name')->get('key');

Replace 'driver_name' with 'file', 'redis', or 'memcached' depending on your setup.

The put method saves data with a key and expiration time as a DateTime or DateInterval instance.

Examples

This saves 'Alice' under 'username' in a file cache for 1 hour, then retrieves it.

Laravel

Cache::driver('file')->put('username', 'Alice', now()->addSeconds(3600));
$username = Cache::driver('file')->get('username');

This stores the number 10 in Redis cache for 10 minutes and then gets it back.

Laravel

Cache::driver('redis')->put('count', 10, now()->addSeconds(600));
$count = Cache::driver('redis')->get('count');

This caches an array of settings in Memcached for 30 minutes and retrieves it.

Laravel

Cache::driver('memcached')->put('settings', ['theme' => 'dark'], now()->addSeconds(1800));
$settings = Cache::driver('memcached')->get('settings');

Sample Program

This example stores a greeting message in the file cache for 5 minutes and then retrieves and prints it.

Laravel

<?php
use Illuminate\Support\Facades\Cache;

// Store a value in file cache for 5 minutes
Cache::driver('file')->put('greeting', 'Hello, Laravel!', now()->addSeconds(300));

// Retrieve the cached value
$message = Cache::driver('file')->get('greeting');

// Output the message
echo $message;

Important Notes

File cache stores data on your server's disk and is simple to use but slower than Redis or Memcached.

Redis and Memcached are in-memory caches, so they are faster and good for shared or large-scale apps.

Make sure Redis or Memcached servers are installed and running before using their drivers.

Summary

Cache drivers let you save and get data quickly to speed up your app.

Use 'file' for simple local caching, 'redis' or 'memcached' for faster, shared caching.

Always set how long cached data should live to keep it fresh.

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