php - How to access objects using string?

Question

I know accessing object's properties dynamically using string e.g.

$obj->{$string};

But what about objects themselves?

Like I have string

$obj = '$model->property';

How to use this?

For example in if statement, to have something like

if($model->property) but by using this string?

Tried if({$obj}), if(${$obj})... nothing works.

I don't know if it even possible, but maybe?

@ka_lin tried eval, doesn't work, with eval I've got "Parse error: syntax error, unexpected end of file" — krystian2160
– krystian2160, Commented May 5, 2018 at 11:16
@ka_lin okay, my bad. added ";" now no exception. But {{ dd(eval('$model->id;')) }} gives me null hmmm. Idk, gives me only null all time — krystian2160
– krystian2160, Commented May 5, 2018 at 11:19
@ka_lin strange, but {{ dd($model->id) }} returns me 77 and {{ dd(eval('$model->id;')) }} null — krystian2160
– krystian2160, Commented May 5, 2018 at 11:37
Don't do this. What you are attempting is a bad practice, which will only lead to pain and misery. Besides, you are braking object's encapsulation — tereško
– tereško, Commented May 5, 2018 at 13:32

Nigel Ren · Accepted Answer · 2018-05-05 11:21:48Z

1

I've set up a small test case...

class A {
    public $b = 5;
}

$test = new A();
$var = "test";
echo ${$var}->b;

I think this last line is what your after.

Update:

If you want the object and the property, then the nearest I could get is to use...

class A {
    public $b = 5;
}

$test = new A();
$var = "test->b";
list($var, $property) = explode("->", $var);
echo ${$var}->$property;

answered May 5, 2018 at 11:18

Nigel Ren

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11 Comments

But I need object + property in one string, as string and as one

Can't it be done easier like e.g. ${$var}; ? where $var = "test->b"; (without usting list and explode)

Not as far as I know - maybe someone else can come up with a way of doing it. BUT I would avoid using eval().

@krystian2160 This is the easiest way. You could also loop trough what the array explode returns if you want a variable amount of properties.

@Joas I know Joas, thank you :D. I just wonder why there is no other (easier, simpler) way

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