从子类构造函数中访问父类方法

Question

I am using Laravel 5.3. In my form request which extends the request class I am trying to access method from the parent class but it is throwing an error and I can't seem to see why. My form request constructor looks like the following. Am I missing something here?

The call works when I put it in other methods, just not from the constructor where it ideally needs to be.

Accessing the parent below triggers "Fatal error: Call to a member function get() on null in vendor\\laravel\\framework\\src\\Illuminate\\Http\\Request.php:601"

    protected $test= [];

    public function __construct(myRepositoryInterface $myRepository) {

        $this->myRepository= $myRepository;
        if( parent::has('someName') ){
           $this->test= $myRepository->someMethod(parent::input('someName'));
       }
   }

Answer 1

There are a few problems.

First, Laravel's Form Request class is a subclass of Symfony's Request class. If you take a look at that class, it has this constructor:

public function __construct(array $query = array(), array $request = array(), array $attributes = array(), array $cookies = array(), array $files = array(), array $server = array(), $content = null)
{
    $this->initialize($query, $request, $attributes, $cookies, $files, $server, $content);
}

You created your own constructor and changed the behavior of the Request class, essentially breaking it. You aren't accepting any of the parameters that the superclass requires.

The Call to a member function get() on null gives us a clue. This is the function where get() is being called:

protected function retrieveItem($source, $key, $default)
{
    if (is_null($key)) {
        return $this->$source->all();
    }

    return $this->$source->get($key, $default);
}

Your $source is null. The $source can be something like the headers property, which is null because of your new constructor. The error has nothing to do with the parent class' has method and everything to do with the constructor.

Second, rather than calling parent::has() , you should be calling $this->has() .

Finally, I would take that out of the constructor. Initialize your repository somewhere else. If you do need this to be in your constructor for some reason, try accepting all other parameters and then your repository. Remember to call parent::__construct(...parameters... ) and run your own logic.

Answer 2

您可能会忘记在子构造函数中调用parent :: __ construct（）吗？