Cache drivers (file, Redis, Memcached) in Laravel - Step-by-Step Execution

Concept Flow - Cache drivers (file, Redis, Memcached)

Request data

↓

Check cache driver

↓

Fetch from source

|Yes↓

Return cached data

↓

If no cache, store data in cache

↓

Respond with data

The app checks the selected cache driver for data. If found, it returns cached data. Otherwise, it fetches fresh data, stores it in cache, then returns it.

Execution Sample

Laravel

$data = Cache::driver('file')->get('user_1');
// If not found
if (!$data) {
    Cache::driver('file')->put('user_1', $data, 3600);
}
return Cache::driver('file')->get('user_1');

This code tries to get cached data for 'user_1' from the file cache. If missing, it stores data for 1 hour, then retrieves it again.

Execution Table

Step	Action	Cache Driver	Key	Cache Hit?	Result	Next Step
1	Attempt to get data	file	user_1	No	null	Store data in cache
2	Store data	file	user_1	-	Data stored for 3600s	Get data again
3	Get data again	file	user_1	Yes	Returns cached data	Return data to user
4	Return data	-	-	-	Data sent to user	End

💡 Data found in cache on step 3, returned to user, process ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
cache_data	undefined	null	data stored	cached data	cached data

Key Moments - 3 Insights

Why does the first get return null even if we expect data?

Because the cache is empty initially (see execution_table step 1), so no cached data exists yet.

How does Laravel know where to store the cache data?

Laravel uses the selected driver (file, Redis, Memcached) to decide storage location, shown in execution_table column 'Cache Driver'.

What happens if the cache expires?

The cached data is removed after the set time (3600 seconds here), so next get returns null and data is fetched/stored again.

Visual Quiz - 3 Questions

Look at the execution table, what is the result of the first cache get attempt?

A cached data

B null

C error

D data stored

💡 Hint

Check step 1 in the execution_table under 'Result' column.

At which step is the data stored in the cache?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Look at the 'Action' column in execution_table for storing data.

If we switch the driver to Redis, which column in the execution table changes?

A Cache Driver

B Cache Hit?

C Action

D Result

💡 Hint

The 'Cache Driver' column shows which driver is used.

Concept Snapshot

Laravel cache drivers let you store data temporarily.
Common drivers: file, Redis, Memcached.
Use Cache::driver('name') to select.
Get data with get(key), store with put(key, value, seconds).
If cache miss, fetch fresh data and store.
Cache improves speed by avoiding repeated data fetch.

Full Transcript

This visual execution shows how Laravel cache drivers work. When the app requests data, it first checks the cache using the selected driver like file, Redis, or Memcached. If the data is not found (cache miss), it fetches fresh data from the source, stores it in the cache for a set time, then returns it. On subsequent requests, the cached data is returned directly, speeding up response. The execution table traces each step: first get returns null, then data is stored, then get returns cached data, and finally data is sent to the user. Variables track the cache data state through these steps. Key moments clarify why the first get is empty and how the driver affects storage location. The quiz tests understanding of cache hits, storage steps, and driver changes. This helps beginners see how caching improves app performance by reducing repeated data fetching.

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