Cache tags in Laravel

Introduction

Cache tags help you group related cached items so you can clear them all at once. This keeps your app fast and organized.

You want to clear all cached data related to a specific user after they update their profile.

You cache different types of data but want to clear only one type without affecting others.

You have a blog and want to clear all cached posts when a new post is published.

You want to manage cache for different sections of your app separately.

You want to avoid clearing the entire cache when only some data changes.

Syntax

Laravel

Cache::tags(['tag1', 'tag2'])->put('key', 'value', $seconds);
$value = Cache::tags(['tag1'])->get('key');
Cache::tags(['tag1'])->flush();

Use an array of tags to group cache items.

Flushing a tag removes all cache items with that tag.

Examples

Cache user data with the tag 'users' for 1 hour.

Laravel

Cache::tags(['users'])->put('user_1', $userData, 3600);

Retrieve cached user data by tag and key.

Laravel

$user = Cache::tags(['users'])->get('user_1');

Clear all cached items tagged with 'posts'.

Laravel

Cache::tags(['posts'])->flush();

Sample Program

This example caches a product with two tags: 'products' and 'electronics'. It retrieves and prints the product, then clears all cache tagged 'electronics'. After flushing, trying to get the product returns 'Not found' because the cache was cleared.

Laravel

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

// Store cache with tags
Cache::tags(['products', 'electronics'])->put('product_123', 'Smartphone', 600);

// Retrieve cached item
$product = Cache::tags(['products'])->get('product_123');
echo $product . "\n";

// Clear all electronics products cache
Cache::tags(['electronics'])->flush();

// Try to get the product again after flush
$productAfterFlush = Cache::tags(['products'])->get('product_123', 'Not found');
echo $productAfterFlush . "\n";

Important Notes

Cache tags work only with cache drivers that support tagging, like Redis or Memcached.

Using tags helps avoid clearing unrelated cached data.

Summary

Cache tags group cached items for easy management.

You can clear all items with a tag using flush().

Tags require a compatible cache driver.

Practice

1. What is the main purpose of using cache tags in Laravel?

easy

A. To group cached items for easy management and selective clearing

B. To encrypt cached data automatically

C. To increase cache storage size

D. To log cache hits and misses

Solution

1. Step 1: Understand cache tags concept

   Cache tags allow grouping of cached items under one or more tags.

2. Step 2: Identify the benefit of grouping

   This grouping helps to clear or manage all related cache items easily by tag.

3. Final Answer:

   To group cached items for easy management and selective clearing -> Option A

4. Quick Check:

   Cache tags = group and manage cache [OK]

Hint: Cache tags group items for easy clearing [OK]

Common Mistakes:

• Thinking tags encrypt data
• Assuming tags increase cache size
• Confusing tags with logging features

2. Which of the following is the correct syntax to store a cache item with a tag in Laravel?

easy

A. Cache::tags('users')->put('user_1', 'John', 3600);

B. Cache::put('user_1', 'John')->tags(['users'], 3600);

C. Cache::put('user_1', 'John', 3600)->tags(['users']);

D. Cache::tags(['users'])->put('user_1', 'John', 3600);

Solution

1. Step 1: Recall Laravel cache tag syntax

   The tags() method accepts an array of tags before calling put().

2. Step 2: Check method chaining order

   The correct order is Cache::tags([...])->put(key, value, time).

3. Final Answer:

   Cache::tags(['users'])->put('user_1', 'John', 3600); -> Option D

4. Quick Check:

   tags() before put() with array [OK]

Hint: Use tags() with array before put() [OK]

Common Mistakes:

• Passing tags after put()
• Using string instead of array in tags()
• Chaining methods in wrong order

3. Given the code below, what will be the output of Cache::tags(['products'])->get('item_1'); after Cache::tags(['products'])->flush(); is called?

Cache::tags(['products'])->put('item_1', 'Book', 600);
Cache::tags(['products'])->flush();
$value = Cache::tags(['products'])->get('item_1');
echo $value ?? 'Not found';

medium

A. Not found

B. CacheException

C. null

D. Book

Solution

1. Step 1: Understand flush() effect on tagged cache

   Calling flush() on a tag clears all cached items under that tag.

2. Step 2: Check retrieval after flush

   After flushing, get('item_1') returns null, so the null coalescing operator outputs 'Not found'.

3. Final Answer:

   Not found -> Option A

4. Quick Check:

   flush() clears tagged cache = 'Not found' [OK]

Hint: flush() clears all tagged cache items [OK]

Common Mistakes:

• Expecting cached value after flush
• Confusing flush() with forget()
• Assuming flush() only clears one item

4. Identify the error in the following Laravel cache tag usage:

Cache::tags('sessions')->put('session_1', 'data', 120);
Cache::tags(['sessions'])->flush();

medium

A. Missing cache driver configuration

B. Using string instead of array in tags() method

C. Calling flush() on tags is not allowed

D. put() method requires a closure

Solution

1. Step 1: Check tags() method argument type

   The tags() method requires an array of tags, not a string.

2. Step 2: Identify the incorrect usage

   Passing a string 'sessions' instead of ['sessions'] causes an error.

3. Final Answer:

   Using string instead of array in tags() method -> Option B

4. Quick Check:

   tags() needs array, not string [OK]

Hint: Always pass array to tags() [OK]

Common Mistakes:

• Passing single string instead of array
• Thinking flush() is disallowed
• Assuming put() needs closure

5. You want to cache user profile data and product data separately but clear both caches together when needed. Which is the best way to use cache tags in Laravel to achieve this?

hard

A. Tag user profiles with ['users'] and products with ['products'], then flush both tags separately

B. Use no tags and clear cache manually by keys

C. Tag both user profiles and products with ['app_data'], then flush this tag to clear all

D. Tag user profiles with ['users'] and products with ['products'], then flush(['users', 'products'])

Solution

1. Step 1: Understand grouping with tags

   To clear multiple cache groups together, use a common tag for both.

2. Step 2: Apply a shared tag

   Tag both user and product caches with a shared tag like 'app_data' to flush all at once.

3. Final Answer:

   Tag both user profiles and products with ['app_data'], then flush this tag to clear all -> Option C

4. Quick Check:

   Shared tag groups caches for joint flush [OK]

Hint: Use shared tag to clear multiple caches together [OK]

Common Mistakes:

• Flushing tags separately instead of shared tag
• Not tagging caches for group clearing
• Trying to flush multiple tags in one call incorrectly