Cache configuration in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Laravel Cache Drivers

Which cache driver in Laravel stores cached data in files by default?

A file

B database

C redis

D memcached

💡 Hint

Think about where Laravel stores cache if no other driver is set.

Laravel uses the file driver by default, which stores cached data as files in the storage/framework/cache directory.

❓ component_behavior

intermediate

Cache Configuration Effect on Behavior

If you set the cache driver to 'array' in Laravel's config/cache.php, what happens to the cached data after the request ends?

A Cached data persists permanently until manually cleared.

B Cached data is stored in memory and lost after the request ends.

C Cached data is saved to the database for later use.

D Cached data is stored in Redis and shared across requests.

💡 Hint

Consider what 'array' driver means for data storage scope.

The 'array' cache driver stores data only in PHP arrays during the current request. Once the request finishes, the data is lost.

📝 Syntax

advanced

Correct Cache Configuration Syntax

Which option correctly sets the Redis cache connection in Laravel's config/cache.php?

Laravel

return [
    'default' => env('CACHE_DRIVER', 'file'),
    'stores' => [
        'redis' => [
            'driver' => 'redis',
            'connection' => 'cache',
        ],
    ],
];

A 'connection' => 'default',

B 'connection' => 'redis',

C 'connection' => 'cache',

D 'connection' => 'database',

💡 Hint

Check the default Redis connection name used for caching in Laravel.

Laravel uses the Redis connection named 'cache' for caching by default, which is separate from the default Redis connection.

🔧 Debug

advanced

Debugging Cache Store Not Found Error

You get an error: Cache store [memcached] is not defined. What is the most likely cause?

A The memcached store is not configured in config/cache.php stores array.

B The cache driver is set to 'file' but memcached is used in code.

C The memcached PHP extension is not installed or enabled.

D The Redis server is down causing fallback to memcached.

💡 Hint

Check the cache stores configuration for memcached.

This error means Laravel cannot find a cache store named 'memcached' in the configuration. It must be defined in the stores array.

❓ state_output

expert

Cache Expiration Behavior

Given this Laravel cache code:

Cache::put('key', 'value', 10);
$value = Cache::get('key');

What is the value of $value immediately after running this code?

Laravel

Cache::put('key', 'value', 10);
$value = Cache::get('key');

A An empty string

B null

C Throws an exception

D 'value'

💡 Hint

Consider the cache expiration time and when you retrieve the value.

The cache expiration time is 10 minutes, so immediately after putting the value, it is available and returned as 'value'.

Practice

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

easy

A. To manage user authentication settings

B. To define database table structures

C. To control how temporary data is stored to speed up the application

D. To configure email sending options

Solution

1. Step 1: Understand cache role in Laravel

   Cache stores temporary data to reduce repeated work and speed up the app.

2. Step 2: Identify cache configuration purpose

   Cache configuration sets how and where this temporary data is saved.

3. Final Answer:

   To control how temporary data is stored to speed up the application -> Option C

4. Quick Check:

   Cache configuration = speed up app by storing temporary data [OK]

Hint: Cache config controls temporary data storage for speed [OK]

Common Mistakes:

• Confusing cache with database setup
• Mixing cache with authentication or email settings
• Thinking cache stores permanent data

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

easy

A. 'driver' => 'redis',

B. 'default' => env('CACHE_DRIVER', 'file'),

C. 'cache' => 'database',

D. 'default_driver' => 'memcached',

Solution

1. Step 1: Check Laravel cache config syntax

   The default cache driver is set with the key 'default' using env() helper.

2. Step 2: Match correct syntax

   'default' => env('CACHE_DRIVER', 'file'), uses 'default' => env('CACHE_DRIVER', 'file'), which is correct Laravel pattern.

3. Final Answer:

   'default' => env('CACHE_DRIVER', 'file'), -> Option B

4. Quick Check:

   Default cache driver set with 'default' key [OK]

Hint: Default cache driver uses 'default' key with env() [OK]

Common Mistakes:

• Using wrong key names like 'driver' or 'cache'
• Not using env() helper for flexibility
• Setting keys that don't exist in Laravel config

3. Given this snippet from config/cache.php:

'stores' => [
    'file' => [
        'driver' => 'file',
        'path' => storage_path('framework/cache/data'),
    ],
    'redis' => [
        'driver' => 'redis',
        'connection' => 'cache',
    ],
],
'default' => 'redis',

What cache store will Laravel use by default?

medium

A. array

B. file

C. database

D. redis

Solution

1. Step 1: Identify the 'default' cache driver

   The config sets 'default' => 'redis', so Redis is the default store.

2. Step 2: Confirm Redis store exists

   The 'stores' array includes a 'redis' store with proper driver and connection.

3. Final Answer:

   redis -> Option D

4. Quick Check:

   Default cache store = redis [OK]

Hint: Default key value shows which cache store is used [OK]

Common Mistakes:

• Assuming 'file' is default because it appears first
• Ignoring the 'default' key value
• Confusing store names with driver names

4. You set the cache driver to 'redis' in .env but Laravel still uses the file cache. What is the most likely cause?

medium

A. You forgot to clear the config cache with php artisan config:clear

B. Redis is not installed on your system

C. The 'file' driver is always used by default

D. You need to restart the web server

Solution

1. Step 1: Understand Laravel config caching

   Laravel caches config files for performance, so changes in .env may not apply immediately.

2. Step 2: Identify how to apply .env changes

   Running php artisan config:clear clears cached config, allowing new .env values to take effect.

3. Final Answer:

   You forgot to clear the config cache with php artisan config:clear -> Option A

4. Quick Check:

   Clear config cache to apply .env changes [OK]

Hint: Clear config cache after .env changes [OK]

Common Mistakes:

• Assuming Redis must be installed locally for Laravel to use it
• Thinking file driver is always default
• Restarting server without clearing config cache

5. You want to configure Laravel cache to use the database driver with a custom prefix to avoid key conflicts. Which of these config/cache.php settings correctly achieves this?

hard

A. 'default' => 'database', 'prefix' => 'myapp_cache_', 'stores' => ['database' => ['driver' => 'database', 'table' => 'cache']],

B. 'default' => 'file', 'prefix' => 'cache_', 'stores' => ['database' => ['driver' => 'database', 'table' => 'cache_data']],

C. 'default' => 'database', 'prefix' => 'cache_', 'stores' => ['database' => ['driver' => 'database', 'table' => 'cache']],

D. 'default' => 'redis', 'prefix' => 'myapp_', 'stores' => ['database' => ['driver' => 'database', 'table' => 'cache']],

Solution

1. Step 1: Set default driver to database

   The 'default' key must be 'database' to use the database cache driver.

2. Step 2: Set a custom prefix and database store

   The 'prefix' key should be 'myapp_cache_' to avoid conflicts, and the 'stores' array must define 'database' with correct driver and table.

3. Final Answer:

   'default' => 'database', 'prefix' => 'myapp_cache_', 'stores' => ['database' => ['driver' => 'database', 'table' => 'cache']], -> Option A

4. Quick Check:

   Default driver + prefix + database store set correctly [OK]

Hint: Set 'default', 'prefix', and 'stores.database' keys properly [OK]

Common Mistakes:

• Not matching default driver with store name
• Using wrong prefix format or missing prefix
• Setting default to wrong driver