PHP making a protected property public at runtime

Question

Problem: I don't want to expose $myProperty, that is it shouldn't be public, but I need it to be public just for __toString():

class A
{
    protected $myProperty;

    public function __toString()
    {
        return json_encode($this);
    }
}

I know that ReflectionProperty class has a method named setAccessible(), but how I'm supposed to use it before returning the string?

EDIT: as per comments, I need compatibility with PHP 5.3.x, that is no JSonSerializable class.

I'd better implement [`JsonSerializable`](http://php.net/manual/en/jsonserializable.jsonserialize.php) interface in order to state clearly which fields will be serialized, and which not. — moonwave99, Dec 18 '12 at 00:47
I'd have to say that `setAccessible()` probably falls under the category of "evil magic that you should never use". It's interesting, but should never be necessary in production code. — , Dec 18 '12 at 00:47
@gremo well that's basically the same - you don't implement the interface, and you call the method explicitly when you need it ^^ — moonwave99, Dec 18 '12 at 00:50
@duskwuff can you explain better with it's evil? Reflection is evil for you? — gremo, Dec 18 '12 at 00:50
Anyway my fav solution is to rely on [annotations](https://github.com/schmittjoh/metadata) when serializing: you take advantage of reflection but you don't mess with hardcoding inside the class itself. — moonwave99, Dec 18 '12 at 00:55
@Gremo: It's "evil" in that it breaks the contract of field protection. If the field isn't actually private, don't make it private. :) — , Dec 18 '12 at 01:16

hakre · Accepted Answer · 2012-12-18T01:21:31.753

3

As per PHP 5.3 use get_object_vars inside the __toString() method:

public function __toString()
{
    return json_encode(get_object_vars($this));
}

Usage Demo:

class A
{
    protected $myProperty = 'hello';

    public function __toString()
    {
        return json_encode(get_object_vars($this));
    }
}

echo new A;

Output:

{"myProperty":"hello"}

Tip: Create the JsonSerializable interface your own and implement the jsonSerialize() method your own to be upwards compatible. Call the function when you need it and/or call it inside __toString():

public function __toString()
{
    return json_encode($this->jsonSerialize());
}

edited Dec 18 '12 at 01:21

answered Dec 18 '12 at 00:51

hakre

193,403
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Interesting... this will work because the protected property is in the scope, right? – gremo Dec 18 '12 at 00:52
Exactly. Will also give private properties. As well as with `(array) $this` but that one has unwanted side-effects so `get_object_vars` is better. – hakre Dec 18 '12 at 00:56
Curious, is `(object)` cast here necessary? – zerkms Dec 18 '12 at 01:04
@zerkms: technically not, because `json_encode` will it encode as json object because of non-numeric keys. Edited. (nice spot, thx) – hakre Dec 18 '12 at 01:20

Mike Brant · Answer 2 · 2012-12-18T02:57:52.730

0

Why don't you simply build a PHP stdClass object and then serialize it to JSON, since when you deserialize from JSON, that is exactly what you get anyway.

Maybe something like this:

public function __toString() {
   $return = new stdClass();
   $properties = get_object_vars($this);
   foreach ($properties as $key => $value) {
       $return->$key = $value;
   }
   return json_encode($return);
}

edited Dec 18 '12 at 02:57

answered Dec 18 '12 at 00:51

Mike Brant

70,514
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PHP making a protected property public at runtime

2 Answers2