creating a chainable method in laravel

Question

I have been trying to create my own chainable method in laravel' eloquent but I'm missing something and not sure what. This may sound a little bit nuts but have a look at my function below to get a better idea of what I'm trying to say.

class Post extends Eloquent{
    public static function custom_wh($data){
        return static::where_in('categories_id', $data, 'AND');
    }
}

//this works fine
$posts = Post::custom_wh(array(1, 2, 3))->get();

//but this says custom_wh is not defined in the query class
$posts = Post::where_in('tags', array(2, 3, 4), 'AND')->custom_wh(array(1, 2, 3))->get();

if I understand correctly then my method is not eligible to chain after another method? So I guess my question is how can I create a chainable method in my model?

P.S I have looked into the laravel's query builder class where I have seen that the chainable methods returns the instance of that object but I couldn't find a way to return the object other than the way I've done in the code above. Any kind of suggestion or advice is highly appreciated. Thanks in advance.

Answer 1

You can do that in Laravel with the "query scopes". You can find the doc here.

You just have to write a function with the prefix scope and you will be able to chain this method like the other query builder ones :

class Post extends Eloquent {

    public function scopeWhereCategories($query, $categories)
    {
        return $query->whereIn('categories_id', $categories, 'AND');
    }

}

$posts = Post::whereCategories([1, 2, 3])->get();
$posts = Post::orderBy('date')->whereCategories([1, 2, 3])->take(5)->get();

Answer 2

OK... This may warp your brain a bit but stick with me. The actual method defined is _where(). So how does both Post::where and $post->where end up calling the _where() method? The answer is 'magic'. :D

PHP has these things called 'magic methods' which enable some very dynamic behaviour. In this case Laravel is using __callStatic() and __call() to handle calls to undefined methods. This enabled the same method to be called statically and non-statically.

public static function __callStatic($method, $parameters)
{
    // Create a new instance of the called class, in this case it is Post
    $model = get_called_class();

    // Call the requested method on the newly created object
    return call_user_func_array(array(new $model, $method), $parameters);
}

So basically Post::where() is just shorthand for $post = new Post; $post->where()

From here the request goes to __call() in which there is an array of underscored method names. If the requested method is in the list of underscored names, then $this->_method() is called and returned.

But this is still not the whole story. Drew is correct in that 'where_in' returns a Query object. Most of the ORM chaining methods you are familiar with are actually part of the ORM Query object. Here is the whole process.

• Post::where( ... )
• Post::__callStatic( 'where', ... )
• $post->__call( 'where', ... )
• $query->_call( 'where', ... )
• $query->_where( ... )

The class you want to extend is the Query that is used by Model. There is no way add another method name to the list of underscored methods defined in __call(). You will have to copy __call() in it's entirety into your Query definition in order to enable your new method to have that behaviour.

I have accomplished this in my projects be pointing Eloquent ( the alias for the Laravel model ) to my extended version, enabling all my models to use the extended Query methods.

// application/libraries/mylib/query.php
namespace MyLib;

class Model extends \Laravel\Model {

    // Tell \MyLib\Model to use \MyLib\Query instead of Laravels Query
    protected function query()
    { 
        return new \MyLib\Query($this);
    } 

}

// application/libraries/mylib/query.php
namespace MyLib;

class Query extends \Laravel\Database\Eloquent\Query {

    function _my_method() { ... }

    function __call() { ... }
}

// application/config/application.php
'aliases' => array(
    ...
    'Eloquent' => 'MyLib\\Model',
    ...
)

http://php.net/manual/en/language.oop5.magic.php https://github.com/laravel/laravel/blob/master/laravel/database/eloquent/model.php#L734 https://github.com/laravel/laravel/blob/master/laravel/database/eloquent/query.php#L274