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Reading Serialized PHP

aaronarney profile image Aaron ・1 min read

Serializing data is simply converting a value into a string. Imagine you had an array in PHP that you wanted to serialize, it would look something like the following...

$arr = [
    'one' => 'val',
    'two' => 'val',
];

$serializedArray = serialize($arr);

/** 
echo $serializedArray;

output:
"a:2:{s:3:"one";s:3:"val";s:3:"two";s:3:"val";}"
**/

Let's dissect it.

  • a:2 - The proceeding value is an array of length 2
  • s:3 - This item is a string of length 3 with a value of val
  • s:3 - This item is also a string of length 3 and value of val

You can imagine how different data types are represented in this fashion.

  • string - s:length:value
  • int - i:value
  • bool - b:value
  • array - a:size:{key definition;value definition;}
  • object - O:strlen(class name):object name:object size:{s:length:property name:property definition;(repeated per property)}

Pretty easy to understand once you know the format.


Resources:

Discussion

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object - O:strlen(class name):class name:object size:{s:length:property name:property definition;(repeated per property)}

 

While I can appreciate and understand the semantics of noting (class name), I don't believe that is technically correct. As far as I know, you can't serialize a class without first instantiating it (unless perhaps doing something fancy with reflection). This instantiation is what creates an object, which is what is serialized. So I believe my example is accurate.

 

Look into serialized object. This name is a class name, not an object name. The object have no name.

OK, after thinking about it a bit more critically I see what you're saying and I agree you are correct.

To those wanting to follow along...
Since serialize is used to essentially instruct PHP on how to recreate a value/variable, it needs to know what class to instantiate a new object with. That is what Vlastimil is pointing out, that serialization isn't storing the name of the object, but rather a reference to which class it inherits its methods/properties from.