Laravel服务提供商和服务容器

Question

in laravel to access query,we use DB facades

DB::select()

from alanstorm website http://alanstorm.com/binding_objects_as_laravel_services i learn that DB facade use callstatic method that lead to DB::app['db']->select(). app is laravel service container object which all the services binded into it. i use vardump php method var_dump(app['db']) and i see the service container returns an Illuminate\Database\DatabaseManager object. from DatabaseManager class that implement ConnectionResolverInterface i dont see the select method defined there. i want to ask how app['db'] can get access to select method. thanks before

Answer 1

DatabaseManager class implements __call() method if you call a method on that class that doesn't exist it's immediately passed as an argument to __call(), which is one of php's magic methods.

that calls connection class with the method you passed.

here's the method implementation in Illuminate\Database\DatabaseManager

/**
 * Dynamically pass methods to the default connection.
 *
 * @param  string  $method
 * @param  array   $parameters
 * @return mixed
 */
public function __call($method, $parameters)
{
    return $this->connection()->$method(...$parameters);
}