Storing and retrieving cache in Laravel

Introduction

Cache helps your app remember data so it can load faster next time. It saves time by not doing the same work again.

When you want to save database query results to speed up page loading.

When you want to store user settings temporarily for quick access.

When you want to keep API response data to avoid repeated calls.

When you want to save computed values that take time to generate.

When you want to reduce server load by reusing stored data.

Syntax

Laravel

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

// Store data in cache
Cache::put('key', 'value', $seconds);

// Retrieve data from cache
$value = Cache::get('key', 'default');

// Store data forever
Cache::forever('key', 'value');

// Remove data from cache
Cache::forget('key');

Use Cache::put to save data with a time limit in seconds or as a DateTime instance.

Use Cache::get to get data; it returns a default if the key is missing.

Examples

Stores a username for 1 hour and then retrieves it.

Laravel

<?php
Cache::put('username', 'alice', 3600); // Store 'alice' for 1 hour
$name = Cache::get('username');

Tries to get a key that does not exist, returns 'guest' as default.

Laravel

<?php
$value = Cache::get('non_existing_key', 'guest');

Saves data permanently until manually removed.

Laravel

<?php
Cache::forever('site_name', 'My Website');
$name = Cache::get('site_name');

Deletes the 'username' key and tries to get it, returning 'not found'.

Laravel

<?php
Cache::forget('username');
$name = Cache::get('username', 'not found');

Sample Program

This program shows how to store data temporarily and permanently in cache, retrieve it, and handle expiration and removal.

Laravel

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

// Store a value in cache for 10 seconds
Cache::put('greeting', 'Hello, Laravel!', 10);

// Retrieve and print the cached value
echo "Cached greeting: " . Cache::get('greeting', 'No greeting found') . "\n";

// Wait 11 seconds to let cache expire
sleep(11);

// Try to get the expired cache
echo "After expiration: " . Cache::get('greeting', 'Cache expired') . "\n";

// Store a value forever
Cache::forever('welcome', 'Welcome to the site!');

// Retrieve and print the forever cached value
echo "Forever cached message: " . Cache::get('welcome') . "\n";

// Remove the forever cached value
Cache::forget('welcome');

// Try to get the removed cache
echo "After removal: " . Cache::get('welcome', 'No message found') . "\n";

Important Notes

Cache::put has time complexity O(1) for storing data.

Cache::get also works in O(1) time to retrieve data.

Common mistake: forgetting to set expiration time, which uses the default TTL from config.

Use cache for data that is expensive to get or compute but changes occasionally.

Summary

Cache stores data to speed up your app by avoiding repeated work.

Use Cache::put to save with expiration, Cache::get to retrieve safely with default.

Use Cache::forever for permanent storage and Cache::forget to remove data.

Practice

1. What does the Cache::put('key', 'value', 60) method do in Laravel?

easy

A. Stores 'value' permanently in cache without expiration

B. Retrieves 'value' from cache with 'key' and expires in 60 seconds

C. Deletes the cache entry with 'key' after 60 minutes

D. Stores 'value' in cache under 'key' for 60 minutes

Solution

1. Step 1: Understand Cache::put method

   The Cache::put method stores data in the cache with a key and expiration time in minutes.

2. Step 2: Analyze the parameters

   Here, 'key' is the cache key, 'value' is the data stored, and 60 means it expires after 60 minutes.

3. Final Answer:

   Stores 'value' in cache under 'key' for 60 minutes -> Option D

4. Quick Check:

   Cache::put stores with expiration = A [OK]

Hint: Cache::put stores with minutes expiry, not seconds [OK]

Common Mistakes:

• Confusing expiration time units (seconds vs minutes)
• Thinking Cache::put retrieves data
• Assuming Cache::put stores data permanently

2. Which of the following is the correct syntax to retrieve a cached value with a default fallback in Laravel?

easy

A. Cache::get('key', 'default')

B. Cache::retrieve('key', 'default')

C. Cache::fetch('key', 'default')

D. Cache::find('key', 'default')

Solution

1. Step 1: Identify Laravel cache retrieval method

   Laravel uses Cache::get to retrieve cached data safely.

2. Step 2: Check method parameters

   The second parameter is the default value returned if the key is not found.

3. Final Answer:

   Cache::get('key', 'default') -> Option A

4. Quick Check:

   Cache::get with default = A [OK]

Hint: Use Cache::get to retrieve with default fallback [OK]

Common Mistakes:

• Using non-existent methods like retrieve or fetch
• Forgetting the default fallback parameter
• Using Cache::put instead of Cache::get

3. What will be the output of this Laravel code snippet?

Cache::put('count', 5, 10);
$value = Cache::get('count', 0);
echo $value;

medium

A. 0

B. null

C. 5

D. Error

Solution

1. Step 1: Store value in cache

   The code stores the integer 5 under the key 'count' with expiration 10 minutes.

2. Step 2: Retrieve value from cache

   Then it retrieves 'count' with default 0. Since the key exists, it returns 5.

3. Final Answer:

   5 -> Option C

4. Quick Check:

   Cache::get returns stored value if exists = B [OK]

Hint: Cache::get returns stored value, not default if key exists [OK]

Common Mistakes:

• Assuming default value is always returned
• Confusing expiration time with immediate deletion
• Expecting null or error instead of stored value

4. Identify the error in this Laravel cache usage:

Cache::put('user', 'Alice');
$value = Cache::get('user');
echo $value;

medium

A. Cache::put requires expiration time as third argument

B. Cache::get requires a default value parameter

C. Cache::put key must be numeric

D. Cache::get cannot be used without Cache::forever

Solution

1. Step 1: Check Cache::put usage

   Cache::put requires three parameters: key, value, and expiration time in minutes.

2. Step 2: Identify missing expiration

   The code misses the expiration time, so it will cause an error or unexpected behavior.

3. Final Answer:

   Cache::put requires expiration time as third argument -> Option A

4. Quick Check:

   Cache::put needs expiration time = D [OK]

Hint: Always provide expiration time with Cache::put unless using forever [OK]

Common Mistakes:

• Omitting expiration time in Cache::put
• Thinking Cache::get always needs default
• Believing keys must be numeric

5. You want to store a user's settings permanently in cache and then remove them later. Which sequence of Laravel cache methods is correct?

hard

A. Cache::store('settings', $data); Cache::remove('settings');

B. Cache::forever('settings', $data); Cache::forget('settings');

C. Cache::put('settings', $data, 0); Cache::delete('settings');

D. Cache::save('settings', $data); Cache::clear('settings');

Solution

1. Step 1: Store data permanently

   Use Cache::forever to store data without expiration.

2. Step 2: Remove cached data

   Use Cache::forget to delete the cached key when needed.

3. Final Answer:

   Cache::forever('settings', $data); Cache::forget('settings'); -> Option B

4. Quick Check:

   Permanent store + forget = C [OK]

Hint: Use forever to store permanently, forget to delete [OK]

Common Mistakes:

• Using wrong method names like delete or remove
• Passing 0 as expiration to put for permanent storage
• Confusing Cache::store or Cache::save as valid methods