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Serializable::serialize

(PHP 5 >= 5.1.0, PHP 7)

Serializable::serializeString representation of object

Description

abstract public string Serializable::serialize ( void )

Should return the string representation of the object.

Note:

This method acts as the destructor of the object. The __destruct() method will not be called after this method.

Parameters

This function has no parameters.

Return Values

Returns the string representation of the object or NULL

Errors/Exceptions

Throws Exception when returning other types than strings and NULL.

See Also

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User Contributed Notes 2 notes

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18
crog at gustavus dot edu
3 years ago
The documentation here is somewhat misleading. Where it says "This method acts as the destructor of the object. The __destruct() method will not be called after this method," I believe the intent is not that the destructor is not run on the object itself, but that the destructor is not called /as part of the serialization process/.

That is, the object will still be destructed as it goes out of scope as normal, but the destructor is not called as a part of the object's serialization.
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1
John
20 days ago
I don't like the bad docs here, which are wrongly claiming that "serialize(): This method acts as the destructor of the object. The __destruct() method will not be called after this method.".

They are simply meaning that serialize() will NOT call __destruct(). That is the ONLY thing they mean.

Your object that is being serialized will continue to live as a normal object. So you should NOT treat serialize() as your destructor! Treat your object as a still-living copy that the user may be using!

The destructor will always run as normal, later, when your object goes out of scope (or is forcibly unset() by you)).

Example with proof:

<?php

class A implements Serializable
{
    public
$data = [];

    public function
__destruct()
    {
        echo
"Destruct of A called.\n";
    }

    public function
serialize()
    {
       
printf("- Serialize of %s called.\n", static::class);
        return
serialize($this->data);
    }

    public function
unserialize($serialized)
    {
       
printf("- Unserialize of %s called.\n", static::class);
       
$this->data = unserialize($serialized);
    }
}

class
B extends A
{
    public function
__destruct()
    {
        echo
"Destruct of B called.\n";
    }
}

$a = new A();
$a->data['inner_b'] = new B();
var_dump($a);

echo
"-----------------\n";
echo
"Calling serialize($a):\n";
$str = serialize($a);
echo
"-----------------\n";
echo
"End of script shutdown from here on:...\n";

?>

Result:

```
object(A)#1 (1) {
  ["data"]=>
  array(1) {
    ["inner_b"]=>
    object(B)#2 (1) {
      ["data"]=>
      array(0) {
      }
    }
  }
}
-----------------
Calling serialize($a):
- Serialize of A called.
- Serialize of B called.
-----------------
End of script shutdown from here on:...
Destruct of A called.
Destruct of B called.
```
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