How to add property to object in PHP >= 5.3 strict mode without generating error

Question

This has to be simple, but I can't seem to find an answer....

I have a generic stdClass object $foo with no properties. I want to add a new property $bar to it that's not already defined. If I do this:

$foo = new StdClass();
$foo->bar = '1234';

PHP in strict mode complains.

What is the proper way (outside of the class declaration) to add a property to an already instantiated object?

NOTE: I want the solution to work with the generic PHP object of type stdClass.

A little background on this issue. I'm decoding a json string which is an array of json objects. json_decode() generates an array of StdClass object. I need to manipulate these objects and add a property to each one.

Try passing TRUE as a 2nd parameter to json_decode. It'll give you an associative array instead of an array of objects. — gen_Eric
– gen_Eric, Commented Jul 23, 2012 at 18:54
PHP in strict mode does not complain about that. 3v4l.org/kn0hi — hakre
– hakre, Commented Apr 18, 2013 at 17:09
I don't know why this has been closed since this is a perfectly valid question. I have an exact similar question right now. — Steven
– Steven, Commented May 30, 2014 at 18:14
Can any of the people who've upvoted this question and its answers explain what exactly the supposed error here is? Even the recently passed RFC which will make dynamic properties an error in PHP 9.0 explicitly allows them on stdClass, because that's kind of the point of it. I can only think there is actually some "code style" tool which people are blindly "tricking" with the answers below. — IMSoP
– IMSoP, Commented Jan 18, 2022 at 15:27

iambriansreed · Accepted Answer · 2013-04-22 22:50:47Z

163

If you absolutely have to add the property to the object, I believe you could cast it as an array, add your property (as a new array key), then cast it back as an object. The only time you run into stdClass objects (I believe) is when you cast an array as an object or when you create a new stdClass object from scratch (and of course when you json_decode() something - silly me for forgetting!).

Instead of:

$foo = new StdClass();
$foo->bar = '1234';

You'd do:

$foo = array('bar' => '1234');
$foo = (object)$foo;

Or if you already had an existing stdClass object:

$foo = (array)$foo;
$foo['bar'] = '1234';
$foo = (object)$foo;

Also as a 1 liner:

$foo = (object) array_merge( (array)$foo, array( 'bar' => '1234' ) );

edited Apr 22, 2013 at 22:50

iambriansreed

22.3k6 gold badges66 silver badges81 bronze badges

answered Jul 23, 2012 at 18:45

WWW

9,8782 gold badges32 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Ray Over a year ago

Your solution works, but it hurts my OO heart :) Was hoping for some type of flashy reflection kung foo or something... Going to keep the question open a bit longer and hope for some little known PHP magic.

WWW Over a year ago

@Ray hehehe... I wish I had something more elegant for you. Incidentally, explicitly setting error_reporting(E_STRICT); on PHP 5.3.15-1~dotdeb.0 with Suhosin-Patch, I don't get any errors or notices when attempting to set a non-existent property on a stdClass object. What version of PHP are you using?

Johan Fredrik Varen · Accepted Answer · 2020-05-06 11:11:01Z

163

Do it like this:

$foo = new stdClass();
$foo->{"bar"} = '1234';

now try:

echo $foo->bar; // should display 1234

edited May 6, 2020 at 11:11

Johan Fredrik Varen

3,9548 gold badges36 silver badges43 bronze badges

answered Sep 15, 2015 at 8:55

JM R.

1,7211 gold badge10 silver badges4 bronze badges

6 Comments

Big Money Over a year ago

How do you add a property to a field on an object using this syntax?

Rejaul Over a year ago

'Attempt to assign property of non-object' Error in Laravel

Salar Over a year ago

even the "bar" string can be in a variable: $foo->{$any_variable} = '1234';

Johan Fredrik Varen Over a year ago

I think this is the best answer, as it keeps the object reference intact (which in my case was crucial).

IMSoP Over a year ago

This makes no sense. $foo->{"bar"} is just a different syntax for $foo->bar, which I'm pretty sure will be handled exactly the same by the compiler before the code is ever run, and any decent static analysis tool should treat it the same way too. Can anyone explain what error this supposedly avoids?

|

gen_Eric · Accepted Answer · 2012-07-23 18:57:02Z

11

If you want to edit the decoded JSON, try getting it as an associative array instead of an array of objects.

$data = json_decode($json, TRUE);

answered Jul 23, 2012 at 18:57

gen_Eric

228k42 gold badges304 silver badges343 bronze badges

Comments

Ragnar · Accepted Answer · 2022-01-18 15:13:26Z

9

This is another way:

$foo = (object)null; //create an empty object
$foo->bar = "12345";

echo $foo->bar; //12345

edited Jan 18, 2022 at 15:13

answered Aug 17, 2016 at 18:18

Ragnar

4,6281 gold badge33 silver badges42 bronze badges

Comments

Benjamin Dubois · Accepted Answer · 2012-07-23 18:58:24Z

1

you should use magic methods __Set and __get. Simple example:

class Foo
{
    //This array stores your properties
private $content = array();

public function __set($key, $value)
{
            //Perform data validation here before inserting data
    $this->content[$key] = $value;
    return $this;
}

public function __get($value)
{       //You might want to check that the data exists here
    return $this->$content[$value];
}

}

Of course, don't use this example as this : no security at all :)

EDIT : seen your comments, here could be an alternative based on reflection and a decorator :

 class Foo
 {
private $content = array();
private $stdInstance;

public function __construct($stdInstance)
{
    $this->stdInstance = $stdInstance;
}

public function __set($key, $value)
{
    //Reflection for the stdClass object
    $ref = new ReflectionClass($this->stdInstance);
    //Fetch the props of the object

    $props = $ref->getProperties();

    if (in_array($key, $props)) {
        $this->stdInstance->$key = $value;
    } else {
        $this->content[$key] = $value;
    }
    return $this;
}

public function __get($value)
{
    //Search first your array as it is faster than using reflection
    if (array_key_exists($value, $this->content))
    {
        return $this->content[$value];
    } else {
        $ref = new ReflectionClass($this->stdInstance);

        //Fetch the props of the object
        $props = $ref->getProperties();

        if (in_array($value, $props)) {

        return $this->stdInstance->$value;
    } else {
        throw new \Exception('No prop in here...');
    }
}
 }
}

PS : I didn't test my code, just the general idea...

edited Jul 23, 2012 at 18:58

answered Jul 23, 2012 at 18:37

Benjamin Dubois

9617 silver badges11 bronze badges

2 Comments

Ray Over a year ago

Benjamin, I want to use PHP's generic object class: StdClass. I cannot modify this class.

Benjamin Dubois Over a year ago

Ray, I updated my answer with a solution corresponding to your need, but it's heavy :-/

Ganga · Accepted Answer · 2015-12-18 07:49:46Z

1

I don't know whether its the newer version of php, but this works. I'm using php 5.6

    <?php
    class Person
    {
       public $name;

       public function save()
       {
          print_r($this);
       }
    }

   $p = new Person;
   $p->name = "Ganga";
   $p->age = 23;

   $p->save();

This is the result. The save method actually gets the new property

    Person Object
    (
       [name] => Ganga
       [age] => 23
    )

answered Dec 18, 2015 at 7:49

Ganga

113 bronze badges

1 Comment

Big Tree Over a year ago

I ran several test for the code across php versions and result shows it only works for php 5 and above. any version below php5 throws an error.

Collectives™ on Stack Overflow

How to add property to object in PHP >= 5.3 strict mode without generating error

6 Answers 6

2 Comments

6 Comments

Comments

Comments

2 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

2 Comments

6 Comments

Comments

Comments

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related