README

The filter and action system in Laravel is inspired by WordPress hooks

About

Actions are code snippets that run at specific points in your program. They don't return any value but provide a way to hook into your existing code without causing interference.

Filters are designed to alter data. They always return a value, typically the modified version of the first parameter, which is the default return behavior.

Notes: This works similarly to the Observer design pattern, or the Publisher/Subscriber pattern, which is also related to event-driven architecture.

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Installation

Install using Composer

composer require razu/laravel-hooks

Great! Now you're ready to use laravel-hooks.

ACTION

EVENT

do_action( string $tag, mixed $arg )

The do_action function is used to trigger all callback functions attached to a specified action hook ($tag).

Parameters

$tag (string) (Required) – The name of the action hook that will be triggered. This specifies the point in the code where the action occurs.
$arg (mixed) (Optional) – Additional arguments that can be passed to the functions hooked to this action. Defaults to empty if not provided.

By calling do_action, you execute all functions linked to the specified hook ($tag), passing any optional arguments to each function. This allows custom code to be run at specific points within the application.

LISTENER

add_action( string $tag, callable $callback, int $priority = 10, int $accepted_args = 1 )

The add_action function associates a callback function with a specified hook ($tag) in a Laravel or WordPress-style hook system. Here’s what each parameter does:

Parameters

$tag (string) (Required) The name of the hook to which the callback function should be attached.
$callback (callable) (Required) The function to be executed when the hook is triggered.
$priority (int) (Optional) Determines the order in which the functions associated with a particular hook are executed. Lower numbers correspond to earlier execution. Default value: 10
$accepted_args (int) (Optional) The number of arguments the callback function accepts. Default value: 1

By using add_action, you can ensure that your custom functions are executed at the appropriate points in your application’s lifecycle, allowing you to extend or modify functionality as needed.

FILTER

EVENT

apply_filters( string $tag, mixed $value )

The apply_filters function calls all functions attached to a specific filter hook ($tag). This allows you to modify a value by passing it through multiple filters.

Parameters

$tag (string) (Required) – The name of the filter hook to trigger. This identifies the specific filter to apply.
$value (mixed) (Required) – The value to be filtered. Each function attached to the hook can modify and return this value.

When apply_filters is called, it sequentially runs all functions associated with hook ($tag), passing $value through each one. This allows custom modifications to be made to the value at specific points in the application.

LISTENER

add_filter( string $tag, callable $callback, int $priority = 10, int $accepted_args = 1 )

The add_filter function allows you to modify various types of internal data at runtime by attaching callback functions to specific filter hooks.

Parameters

-$tag (string) (Required) – The name of the filter to which the callback will be added. This specifies the specific filter hook where data modification should occur.

-$callback (callable) (Required) – The callback function to be executed when the filter is applied. This function should process and potentially modify the filtered data.

-$priority (int) (Optional) – Specifies the order in which functions associated with this filter will execute. Lower numbers correspond to earlier execution. Functions with the same priority are executed in the order they were added. The default is 10.

$accepted_args (int) (Optional) – The number of arguments the callback function accepts. The default is 1.

Using add_filter, you can ensure that specific functions modify data when the designated filter is applied, allowing for flexible data processing throughout the application.

Here’s how to pass a callback function:

The callback can be specified in various ways, including:

An anonymous function.
A string referring to a class and method within the application, like OurNamespace\Http\Listener\ourClass@ourHookListenerMethod.
An array format, such as [$object, 'method'].
A globally defined function, such as global_function.

Examples

Using an anonymous function:

add_action('user_registered', function($user) {
    $user->sendEmailVerificationCode();
}, 20, 1);

Using a class method reference as a string:

add_action('user_registered', 'OurNamespace\Http\Listener\ourClass@ourHookListenerMethod', 20, 1);
add_action('user_registered', 'OurNamespace\Http\Controllers\ourController@ourMethodName', 20, 1);

Using an array callback:

add_action('user_registered', [$object, 'ourMethod'], 20, 1);

Usages

Actions

Anywhere in your code, you can define a new action like this:

do_action('user_registered', $user);

Here, user_registered is the action name, which will be used later when the action is being listened to. The $user parameter will be available whenever you listen for the action. This parameter can represent any relevant data.

To listen for your actions, attach listeners at the appropriate points. Another good approach is to add these in the boot() method of your AppServiceProvider.

For example, if you want to hook into the above action, you could do the following:

add_action('user_registered', function($user) {
    $user->sendEmailVerificationCode();
}, 10, 1);

The first argument must be the name of the action. The second argument can be closures, callbacks, or anonymous functions. The third argument specifies the order in which the functions associated with a particular action are executed. Lower numbers correspond to earlier execution, and functions with the same priority are executed in the order in which they were added to the action. The default value is 10. The fourth argument specifies the number of arguments the function accepts, with the default value being 1.

Filters

Filters must always have data coming in and going out to ensure it reaches the browser for output. Your content might pass through multiple filters before finally being displayed. In contrast, actions—though similar to filters—do not require any data to be returned. However, data can still be passed through actions if needed.

Filters are functions in Laravel applications that allow data to be passed through and modified. They enable developers to adjust the default behavior of specific functions.

Here’s an example of how a filter can be used in a application.

In the Product.php model, we have a getAvailable method that builds a query to fetch all available products:

class Product extends Model
{
    public function getAvailable()
    {
        return Product::where('available_at', '<=', now());
    }
}

Using a filter, we can modify this query dynamically:

class Product extends Model
{
    public function getAvailable()
    {
        return apply_filters('products_available', Product::where('available_at', '<=', now()));
    }
}

Now, in the entry point of the application, such as in a module or plugin, you can modify this product availability query.

In the service provider of the module or plugin (ideally within the boot method), we'll register a listener for the filter.

class ModuleServiceProvider extends ServiceProvider
{
    public function boot()
    {
        // Registering a filter to modify the query for available products
        add_filter('products_available', function($query) {
            return $query->where('status', 'active');
        });
    }
}

License

This software is licensed under the (MIT) License. For more details, please refer to the License file.

razu / laravel-hooks

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ACTION

EVENT

LISTENER

FILTER

EVENT

LISTENER

Here’s how to pass a callback function:

Examples

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Actions

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