How to return objects or arrays from a chaining interface in PHP OOP?

Question

I am curious in writing a chaining interface in PHP OOP. I modified this sample code from the php.net website, and I want to take it further - how can I return objects or arrays from this kind of interface?

// Declare a simple class
class TestClass
{
    public $foo;

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

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

$input = (object)array("title" => "page 1");
$class = new TestClass($input);
echo $class;

error,

Catchable fatal error: Method TestClass::__toString() must return a string value in C:\wamp\www\test\2013\php\fluent_interface.php on line 2

Should I use different magic method instead of __toString then?

EDIT: Can I return this as my result,

stdClass Object ( [title] => page 1 )

What exactly do you want it to do?

Dragony
– Dragony

2013-08-22 13:04:50 +00:00
Commented Aug 22, 2013 at 13:04 — Dragony
– Dragony, Commented Aug 22, 2013 at 13:04

Dragony · Accepted Answer · 2013-08-22 13:09:03Z

1

To get what you want you need to use following syntax:

print_r($class->foo);

The __toString() magic method tries to convert your whole class 'TestClass' to a string, but since the magic method is not returning a string, it is showing you that error. Of course you could also rewrite your __toString() method to do the following:

public function __toString()
{
    return print_r($this->foo, true);
}

http://php.net/manual/en/function.print-r.php

http://www.php.net/manual/en/language.oop5.magic.php#object.tostring

answered Aug 22, 2013 at 13:09

Dragony

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3 Comments

Run Over a year ago

but it seems I can't access the properties inside the object, for instance, $class = new TestClass($input); echo $class->title; I get this error Notice: Undefined property: TestClass::$title in C:...fluent_interface.php on line 23 instead of page 1... how can I access the data inside the object then?

Dragony Over a year ago

The foo property in your class contains another object that is your data. In your example you should use this syntax: $class->foo->title

Run Over a year ago

got it by doing that myself before reading your answer. thank you! :D

Alma Do · Accepted Answer · 2013-08-22 13:13:56Z

1

I think you are looking for either print_r or var_export functions:

public function __toString()
{
    return var_export($this->foo, true);
}

and var_export is better since it also return type of value (and, besides, in valid PHP-code format). Note, that __toString() method have nothing common with fluent interface. It's just different things.

answered Aug 22, 2013 at 13:13

Alma Do

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3 Comments

Run Over a year ago

thanks but how can I access the data inside the return object then? for instance, echo $class->title; I want to get page 1 as the result. Is it possible?

Alma Do Over a year ago

I'm not sure what are you trying to achieve. To replace your class instance by those, that was passed to constructor? If yes, why?

Run Over a year ago

sorry, I got the answer by doing this echo $class->foo->title; thanks for the help.

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