How to set class variables dynamically?

Question

Consider the following code:

class Project
{
    public $ProjectID;
}    
class Work
{
    public $WorkID;
}    

public function insert($pData, $tableName)
{
//generate insert here
    $pData->{$tableName . 'ID'} = $result->getId();
}

$p = new Project();
$w = new Work();
insert($w, 'Work');
insert($p, 'Project');

echo $p . ' -- ' . $w;

Now how would I go about setting the variable in a dynamic way? I'm building a data layer. The $pData->{$tableName . 'ID'} doesn't seem to work...

For `$w` it would be `$w.WorkID = 7` and for `$p` it would be `$p.ProjectID = 7`. — Kees C. Bakker, May 20 '13 at 18:39
I don't think it is clear what you mean by "dynamic" nor where / why you came up with this function setToSeven, nor what is your problem that you need solving with something "dynamic". — user1122069, May 20 '13 at 18:42
I would be more inclined to use [interfaces](http://php.net/manual/en/language.oop5.interfaces.php) and standardize the name of the property... That way I could have `setToSeven()` just operate on $object->id instead of having a varying property name. — dougBTV, May 20 '13 at 18:42
missing from the question is what is expected from the above code, and the actual result. I suspect that the actual problem here is in the echo statement. Try `print_r($p)` instead. — Jerry, May 20 '13 at 18:46
Well I'm building a data layer and I made a simpeler question that the real complex question I actually have :P — Kees C. Bakker, May 20 '13 at 18:47
OP wants to create properties dynamically at runtime (ala reflection). Possible duplicate of: http://stackoverflow.com/questions/829823/can-you-create-instance-properties-dynamically-in-php — qJake, May 20 '13 at 18:47
Would this help here? http://www.php.net/manual/en/language.oop5.overloading.php#object.set — gen_Eric, May 20 '13 at 18:53
Variables do not need to be created at runtime. Only set dynamically. — Kees C. Bakker, May 20 '13 at 23:12

Jordan Doyle · Answer 1 · 2013-05-20T18:57:10.467

This is what you're looking for:

public function set_to_seven($p_data, $name)
{
    $name = $name . 'ID';
    $p_data->$name = 7;
}

The property name can be a variable. Just like functions:

$p = 'print_r';
$p('StackOverflow');

For future reference: if you need this statically, you're looking for variable variables,

public function set_to_seven($p_data, $name)
{
    $name = $name . 'ID';
    $p_data::$$name = 7;
}

score 2 · Accepted Answer · answered May 20 '13 at 18:50

2

So, you want to dynamically call setters?

$y = new stdClass();
$y->prop1 = "something";

$targetProperty = "prop1";
$y->$targetProperty = "something else";
echo $y->prop1;

//Echos "something else"

That what you're looking for?

answered May 20 '13 at 18:50

dudewad

13,215
6
37
46

score 1 · Answer 3 · answered May 20 '13 at 18:42

1

You can set public properties by accessing them just like any other definition in the class.

$p = new Project();
$p->ProjectID = 5;
echo $p->ProjectID; // prints 5

http://php.net/manual/en/language.oop5.visibility.php

answered May 20 '13 at 18:42

qJake

16,821
17
83
135

Yeah, I know, but I need to set properties dynamically. So I don't know the type of the object and I would like a generic function that sets the key. I'm building a object-relational mapper :) – Kees C. Bakker May 20 '13 at 18:44
Ah, in that case, this question is a duplicate. See my comment on your question. – qJake May 20 '13 at 18:47

score 0 · Answer 4 · answered May 20 '13 at 18:54

This worked for me.

class Project {
    public $ProjectID;
}

function setToSeven($pData, $name) {
    $pData->{$name . "ID"} = 7;
}

$p = new Project();
setToSeven($p, 'Project');

echo $p->ProjectID;

You just need to echo the variable or set up a toString function on the class to echo the class. To String works like this

class Project {
    public $ProjectID;
    public function __toString(){
        return (string)$this->ProjectID;
    }
}

function setToSeven($pData, $name) {
    $pData->{$name . "ID"} = 7;
}

$p = new Project();
setToSeven($p, 'Project');

echo $p;

How to set class variables dynamically?

4 Answers4