Creating Object instance from Posted data - PHP

Question

Hi All

What is the best way of creating and populating an Object from values passed in from a form?

If for example, i have a class Car with properties Colour, Model, Make, Year and a method Save, which will either insert or update the record.

I then have a form that has fields for all these values and it is submitted. I want to create an instance of class Car with the posted values and then call the Save method. All good and well.

But what is the best way of assigning the posted values to the objects internal properties. Assuming this is a simplified scenario and the actual situation would have many more properties, making individual Set calls long-winded.

Is it best to simply call the Set method for each one? Or pass in an array to a method (or the constructor) which then calls the Set methods? Or some other way?

Any advice on best practices is appreciated

Cheers Stuart

Answer 1

If the properties are public:

foreach($_POST as $key => $value)
    $obj->$key = $value;

If they require setters:

foreach($_POST as $key => $value) {
    $set = 'Set' . $key;
    $obj->$set($value);
}

Answer 2

Well, you can convert the post array to an object in one step...

$mypostobject = (object) $_POST;
echo $mypostobject->Colour;

EDIT: added link to PHP docs. http://uk.php.net/manual/en/language.types.object.php

If you want to do this with your own class of object, then some kind of constructor or function that takes the post array and set up your class would be in order.

class MyCar {
  public function __construct($postdata) 
  {
    $this->Colour = $postdata['Colour'];
    // etc
  }
};

$car = new MyCar($_POST);

Answer 3

create a constructor which will take all the attributes

class Car {
  // private members …
  public function __construct($color, $type, $model, $make) {
    // assign your values here
  }
  // other methods
};

if you are dealing with associative arrays, you can also use a constructor with an array as argument:

public function __construct($car_properties) {}

and then loop your properties with

foreach($car_properties as $property => $value) {
  if(isset($value)) $this->property = $value
}

be sure to sanitize/validate your input beforehand! (can’t stress this often enough)

Answer 4

You can use a bit of Reflection magic:

public function loadFromArray($array) {
    $class = new ReflectionClass(get_class($this));
    $props = $class->getProperties();
    foreach($props as $p) {
         if (isset($array[$p->getName()])
              $p->setValue($this, $array[$p->getName]);
    }
}

You can implement this method in a base class and make all yout object inherit from that, so you have this functionality in every object without repeating yourself in any class.

Answer 5

In case the object that you're posting may become more complex than a flat list of properties in the future (think nesting, arrays as values etc.), you could first create a JavaScript object on the client side and post it as JSON inside a single parameter. Then you can simply deserialize the JSON string into a PHP object. PHP 5+ has built-in support for JSON deserialization. Using JSON would allow you to be flexible in how complex your object can be.