Creating dynamic property in a object

Question

I used cakePHP which has a nice feature where the model (if present is already created as a property within your controllers, so effectively I would have access to a property named $this->model_name within my controller without having the create an instance of the model object.

From what I understand all properties must be defined in a class to be able to use it, so is there another way for me to be able to complete the above?

  // Sample code:
  <?php
  class controller {
        public function create_model($model_name) {
              // Assuming that I have spl_autoload enabled to achieve the below:
              $this->$$model_name = new model_name();      
        }
  }

What error you are getting? – Rohit Choudhary Jan 21 '13 at 11:28 — Rohit Choudhary, Jan 21 '13 at 11:28

Vlad Preda · Accepted Answer · 2013-01-21T11:36:58.113

You can do things like this with magic methods (check out _set() and _get() )

Here is some sample code:

class Controller
{
    protected $models;

    public function __get($key)
    {
        return $this->models[$key];
    }

    public function __set($key, $value)
    {
        $this->models[$key] = $value;
    }
}

You can implement your own functionality in __set() and __get(). You can set data with $this->my_model = $something;.

Here is something that's more tailored to your specific example:

public function __get($key) // you will only need __get() now
    {

        if (array_key_exists($key, $this->models) && $this->models[$key] instanceof $key) { 
            return $this->models[$key];
        } else {
            $this->models[$key] = new $key;
            return $this->models[$key];
        }

    }

So now, $this->my_model with try to instantiate my_model if it doesn't exist, and return the current object if it exists. Maybe not the best solution, but added it here so you can understand how it works.

Creating dynamic property in a object

1 Answers1