# Cache

This component implements callbacks and methods for managing cache using WordPress [Transients](https://developer.wordpress.org/apis/handbook/transients/) and [Metadata](https://developer.wordpress.org/apis/handbook/metadata/) API. By default, the cached values are stored in the database, but you can switch to the in-memory cache with [Redis](https://redis.io/) or [Memcached](https://memcached.org/). If you need to disable the HivePress cache, set the `HP_CACHE` constant to `false`:

```php
define( 'HP_CACHE', false );
```

### Quick example <a href="#bkmrk-quick-example" id="bkmrk-quick-example"></a>

The function below counts the number of listings added by a specific user. It caches the listing count to prevent the calculation on every call and stores the cache until some listing is added, removed or updated.

```php
function get_listing_count( $user_id ) {

	// Get the cached value.
	$listing_count = hivepress()->cache->get_user_cache( $user_id, 'listing_count', 'models/listing' );

	if ( is_null( $listing_count ) ) {

		// Count listings.
		$listing_count = HivePress\Models\Listing::query()->filter(
			[
				'user'       => $user_id,
				'status__in' => [ 'draft', 'pending', 'publish' ],
			]
		)->get_count();

		// Cache the calculated value.
		hivepress()->cache->set_user_cache( $user_id, 'listing_count', 'models/listing', $listing_count );
	}

	return $listing_count;
}
```

### Storing cache <a href="#bkmrk-storing-cache" id="bkmrk-storing-cache"></a>

To store a value in cache, call the `set_cache` method with the cache key:

```php
hivepress()->cache->set_cache( 'custom_key', null, 'custom_value' );
```

For grouping the cached values, provide the group name. Both the key and the group name should be as unique as possible to avoid conflicts with other cached values.

```php
hivepress()->cache->set_cache( 'custom_key', 'custom_group', 'custom_value' );
```

You can also set a time limit for storing the cached value:

```php
hivepress()->cache->set_cache( 'custom_key', 'custom_group', 'custom_value', DAY_IN_SECONDS );
```

Set the [model](/developer-docs/framework/models.md) name as a cache group to clear cache automatically when the model objects are updated. For example, the code below clears the cached value if any listing is added, removed, or updated:

```php
hivepress()->cache->set_cache( 'custom_key', 'models/listing', 'custom_value' );
```

Similarly, you can store the cache for a specific user, post, comment or term by ID. For example, if you count the number of listings for a user with ID `123`, you can store it this way:

```php
hivepress()->cache->set_user_cache( 123, 'listing_count', 'models/listing', $listing_count );
```

The `set_post_cache`, `set_comment_cache` and `set_term_cache` methods accept the same parameters.

### Retrieving cache <a href="#bkmrk-retrieving-cache" id="bkmrk-retrieving-cache"></a>

To retrieve a cached value, call the `get_cache` method with the cache key:

```php
$value = hivepress()->cache->get_cache( 'custom_key' );
```

It returns `null` if the cache doesn't exist. For retrieving cache related to some group, provide the group name:

```php
$value = hivepress()->cache->get_cache( 'custom_key', 'custom_group' );
```

Similarly, you can retrieve the cache for a specific user, post, comment or term by ID. For example, HivePress caches the number of listings added by each user, and you can retrieve it this way:

```php
$listing_count = hivepress()->cache->get_user_cache( 123, 'listing_count', 'models/listing' );
```

The `get_post_cache`, `get_comment_cache` and `get_term_cache` methods accept the same parameters.

### Clearing cache <a href="#bkmrk-clearing-cache" id="bkmrk-clearing-cache"></a>

The cache is cleared automatically if the time limit is reached or the related model objects are updated. Also, if the in-memory cache is enabled, it may be cleared if the maximum allowed storage is exceeded.

You can clear the cache explicitly by calling the `delete_cache` method with the cache key:

```php
hivepress()->cache->delete_cache( 'custom_key' );
```

To clear the cache related to some group, provide the group name:

```php
hivepress()->cache->delete_cache( 'custom_key', 'custom_group' );
```

For clearing the whole cache group, skip the cache key parameter:

```php
hivepress()->cache->delete_cache( null, 'custom_group' );
```

Similarly, you can clear the cache for a specific user, post, comment or term by ID. For example, HivePress caches the number of listings added by each user, and you can clear it this way:

```php
hivepress()->cache->delete_user_cache( 123, 'listing_count', 'models/listing' );
```

The `delete_post_cache`, `delete_comment_cache` and `delete_term_cache` methods accept the same parameters.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hivepress.io/developer-docs/framework/components/cache.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.