Storing and retrieving cache in Laravel - Step-by-Step Execution

Concept Flow - Storing and retrieving cache

Start

↓

Check if cache key exists

|Yes↓

Retrieve cached value

↓

Use cached value

↓

End

No↓

Generate data

↓

Store data in cache with key

↓

Use stored data

↓

End

The flow checks if a cache key exists. If yes, it retrieves and uses the cached value. If no, it generates data, stores it in cache, then uses it.

Execution Sample

Laravel

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

$value = Cache::remember('key', 60, fn() => 'data');
return $value;

This code tries to get 'key' from cache. If missing, it stores 'data' for 60 minutes and returns it.

Execution Table

Step	Action	Cache Key Exists?	Cache Operation	Result
1	Check cache for 'key'	No	Cache miss	No value found
2	Generate data	N/A	N/A	'data' generated
3	Store 'data' in cache with key 'key' for 60 minutes	N/A	Cache store	'data' stored
4	Return stored data	N/A	N/A	'data' returned
5	End	N/A	N/A	Process complete

💡 Cache key 'key' was missing initially, so data was generated and stored, then returned.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
value	undefined	undefined	'data'	'data'	'data'

Key Moments - 2 Insights

Why does the code generate data only when the cache key is missing?

Because the execution_table row 1 shows a cache miss, so the code runs the data generation in step 2 before storing it in step 3.

What happens if the cache key exists when Cache::remember runs?

The cache returns the stored value immediately (cache hit), skipping data generation and storage, as shown in execution_table step 4.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'value' after step 2?

A undefined

B 'data'

C null

D 'key'

💡 Hint

Check variable_tracker column 'After Step 2' for 'value'.

At which step does the cache store the data?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at execution_table 'Cache Operation' column for 'Cache store'.

If the cache key existed initially, which step would be skipped?

A Step 2

B Step 3

C Step 1

D Step 5

💡 Hint

Refer to execution_table steps where data generation happens only on cache miss.

Concept Snapshot

Laravel cache stores data by key for a set time.
Use Cache::remember('key', minutes, callback) to get or store.
If key exists, cached value returns immediately.
If missing, callback runs, stores result, then returns it.
This avoids repeated expensive data generation.

Full Transcript

This visual trace shows how Laravel caching works using Cache::remember. First, the code checks if the cache key exists. If it does, the cached value is returned immediately. If not, the code generates the data, stores it in cache with the key for a set time, then returns the data. The variable 'value' holds the cached or generated data. This process helps avoid repeating expensive operations by reusing stored results.

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