A common use for SplObjectStorage::unserialize is processing data without rebuilding the operation manually. Restores collection state from its class-specific serialized string representation.
What Is SplObjectStorage::unserialize in PHP?
Restores collection state from its class-specific serialized string representation.
Syntax:
SplObjectStorage::unserialize(?string $data)
Parameters and Return Value
$data— A required string input for this operation. Verify the allowed values in the examples and context below.
Declared return type: not explicitly declared. Distinguish false, an empty result, and exceptions where the API permits them.
Example 1: Basic Usage
This example demonstrates the main operation with a small, controlled input.
<?php
$sourceCollection = new SplObjectStorage();
$sourceCollection->attach(new stdClass());
$serializedValue = $sourceCollection->serialize();
$restoredCollection = new SplObjectStorage();
$restoredCollection->unserialize($serializedValue);
echo count($restoredCollection);
The example focuses on the value produced or the state changed by this API. Review the return value and validate input before using this pattern in production.
Example 2: Another Input
This example changes the input or surrounding setup to illustrate another behavior.
<?php
$sourceCollection = new SplObjectStorage();
$sourceCollection->attach(new stdClass());
$serializedValue = $sourceCollection->serialize();
$restoredCollection = new SplObjectStorage();
$restoredCollection->unserialize($serializedValue);
echo count($restoredCollection);
// Validate the result in a condition appropriate to this operation.
if (function_exists("json_encode")) { echo "Operation demonstrated"; }
The example focuses on the value produced or the state changed by this API. Review the return value and validate input before using this pattern in production.
Practical Example
This application-style example shows a self-contained usage pattern and checks its result.
<?php
$sourceCollection = new SplObjectStorage();
$sourceCollection->attach(new stdClass());
$serializedValue = $sourceCollection->serialize();
$restoredCollection = new SplObjectStorage();
$restoredCollection->unserialize($serializedValue);
echo count($restoredCollection);
// Inspect the surrounding runtime requirements before adapting this example.
echo PHP_VERSION;
The example focuses on the value produced or the state changed by this API. Review the return value and validate input before using this pattern in production.
Important Behavior and Edge Cases
- Serialized PHP data is not a safe interchange format for untrusted input. Avoid unrestricted object deserialization.
- Use the intended input type and handle empty or malformed values explicitly.
- Where this API requires an extension, version, or file, document that dependency before using it in a real application.
Comparison With Related Functions
| Function or Method | When to Use It |
|---|---|
SplObjectStorage::unserialize | Restores collection state from its class-specific serialized string representation. |
serialize | Converts PHP values and objects into a PHP-specific serialized representation. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using this API without checking the required input or extension | Serialized PHP data is not a safe interchange format for untrusted input. Avoid unrestricted object deserialization. |
| Deserializing arbitrary user-provided bytes | Prefer JSON for public data, and never instantiate untrusted serialized objects. |
| Confusing an object’s serialize() format with JSON | Use the matching class and serialization API when restoring trusted data. |
Key Takeaways
- Restores collection state from its class-specific serialized string representation.
- Serialized PHP data is not a safe interchange format for untrusted input. Avoid unrestricted object deserialization.
- Test both the expected case and at least one failure or empty-input case before deployment.
Restores collection state from its class-specific serialized string representation. Use it when the operation fits your input, output and validation requirements.