Notes on refactoring ZF2's "InputFilter"

1-Notes.md

A few notes from my personal gripes about what InputFilter is and does.

1. InputFilter is a terrible name as the class mixes sanitation and validation. Rename to something far more appropriate (e.g. InputManager?).
2. Data should only be processed, not stored - remove setData()

SoC Article

For example, if both raw and sanitized data are required:

$sanitizedData    = $this->inputManager->sanitize($data->toArray());
$validationResult = $this->inputManager->validate($sanitizedData);

if ($validationResult->isValid()) {
    // hooray!
} else {
    $messages = $validationResult->getMessages();
}

Also, if all we need is the result:

$validationResult = $this->inputManager->sanitizeAndValidate($data->toArray());

if ($validationResult->isValid()) {
    // hooray!
} else {
    $messages = $validationResult->getMessages();
}

CollectionInput.php

<?php

namespace Zend\Input;

use SplPriorityQueue;

class CollectionInput implements InputInterface, CollectionInterface
{
    /**
     * @var SplPriorityQueue
     */
    private $inputs;
    
    private $name;
    
    public function __construct($aName, array $anInputList = [])
    {
        $this->name   = (string) $aName;
        $this->inputs = new SplPriorityQueue();
        $this->insertAll($anInputList);
    }
    
    public function sanitize($aValue)
    {
        foreach ($this->inputs as $input) {
            $name = $input->getName();
            if (isset($aValue[$name])) {
                $aValue[$name] = $input->sanitize($aValue[$name]);
            }
        }
        return $aValue;
    }
    
    public function validate($aValue)
    {
        $results = [];
        foreach ($this->inputs as $input) {
            $name = $input->getName();
            if (isset($aValue[$name])) {
                $results[$name] = $input->validate($aValue[$name]);
            }
        }
        return $results;
    }
    
    public function sanitizeAndValidate($aValue)
    {
        return $this->validate($this->sanitize($aValue));
    }
    
    public function insert(InputInterface $anInput, $aPriority = 0)
    {
        $this->inputs->insert($anInput, $aPriority);
    }
    
    public function insertAll($anInputList)
    {
        foreach ($anInputList as $input) {
            $this->insert($input);
        }
    }
    
    // ...
    
    public function getIterator()
    {
        return $this->inputs;
    }
}

CollectionInterface.php

<?php

namespace Zend\Input;

interface CollectionInterface extends \InteratorAggregate
{
    public function insert(InputInterface $anInput);
    
    public function insertAll($inputs);
    
    public function remove(InputInterface $anInput);
    
    public function removeAll($inputs);
    
    public function contains(InputInterface $anInput);
    
    public function retrieve($anInputName);
}

Input.php

<?php

namespace Zend\Input;

use Zend\Sanitizer\SanitizerInterface;
use Zend\Validator\ValidatorInterface;

/**
 * An implementation of the {@link Zend\Input\InputInterface}
 *
 * @package Zend\Input
 */
class Input implements InputInterface
{
    /**
     * @var string
     */
    protected $name;
    
    /**
     * @var SanitizerInterface
     */
    protected $sanitizer;
    
    /**
     * @var ValidatorInterface
     */
    protected $validator;
    
    
    /**
     * @param string              $aName
     * @param SanitizerInterface  $aSanitizer
     * @param ValidatorInterface  $aValidator
     */
    public function __construct($aName, SanitizerInterface $aSanitizer, ValidatorInterface $aValidator)
    {
        $this->name      = (string) $aName;
        $this->sanitizer = $aSanitizer;
        $this->validator = $aValidator;
    }
    
    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }
    
    /**
     * @param  mixed $aValue
     * @return mixed
     */
    public function sanitize($aValue)
    {
        return $this->sanitizer->sanitize($aValue);
    }
    
    /**
     * @param  mixed $aValue
     * @return \Zend\Validator\ResultInterface
     */
    public function validate($aValue)
    {
        return $this->validator->validate($aValue);
    }
    
    /**
     * @param mixed $aValue
     * @return \Zend\Validator\ResultInterface
     */
    public function sanitizeAndValidate($aValue)
    {
        return $this->validate($this->sanitize($aValue));
    }
}

InputInterface.php

<?php

namespace Zend\Input;

interface InputInterface
{
    public function getName();
    
    public function sanitize($aValue);
    
    public function validate($aValue);
    
    public function sanitizeAndValidate($aValue);
}

Manager.php

<?php

namespace Zend\Input;

/**
 * An implementation of the {@link Zend\Input\ManagerInterface}
 *
 * @package Zend\Input
 */
class Manager implements ManagerInterface
{
    /**
     * @param ContainerInterface $anInputList
     * @param array|\Traversable $aValidationGroup
     */
    public function __construct(CollectionInterface $anInputList, $aValidationGroup)
    {
        foreach ($anInputList as $name => $input) {
            if (!in_array($name, $aValidationGroup)) {
                $anInputList->remove($input);
            }
        }
        $this->insertAll($anInputList);
    }
    
    /**
     * @param  InputInterface[] $anInputList
     * @param  string[]         $aValidationGroup
     * @return self
     */
    public static function withInputs($anInputList, $aValidationGroup)
    {
        return new static(new Collection($anInputList), $aValidationGroup);
    }
    
    /**
     * @param  array
     * @return array
     */
    public function sanitize(array $data)
    {
        return $this->inputs->sanitize($data);
    }
    
    /**
     * @param  array $data
     * @return \Zend\Validator\ResultInterface[]
     */
    public function validate(array $data)
    {
        return $this->inputs->validate($data);
    }
    
    /**
     * @param  array
     * @return \Zend\Validator\ResultInterface[]
     */
    public function sanitizeAndValidate(array $data)
    {
        return $this->inputs->sanitizeAndValidate($data);
    }
}

ManagerInterface.php

<?php

namespace Zend\Input;

interface ManagerInterface
{
    public function sanitize(array $data);
    
    public function validate(array $data);
    
    public function sanitizeAndValidate(array $data);
}

Validator\ResultInterface.php

<?php

namespace Zend\Validator;

interface ResultInterface extends \Serializable, \JsonSerializable
{
    /**
     * Was the validation successful?
     * 
     * @return bool
     */
    public function isValid();
    
    /**
     * List any messages
     * 
     * @return string[]
     */
    public function getMessages();
}

Do you understand the concept of Separation of Concerns? That's the key objective here. Bridge components would be better organized outside of the core library. A Zfc version would be no different than the current version in terms of requirements. It's not complex: If you need a pre-built input module, just use the Zfc version; if you need more flexibility, use the individual components as necessary and roll your own. But, if you need flexibility, you should NOT be forced to load "20 modules" (a gross exaggeration) just for one component.

    "require": {
        "php": ">=5.3.3",
        "zendframework/zend-filter": "self.version",
        "zendframework/zend-validator": "self.version",
        "zendframework/zend-stdlib": "self.version"
    },
    "suggest": {
        "zendframework/zend-servicemanager": "To support plugin manager support"
    },

would become

    "require": {
        "php": ">=5.3.3",
        "zendframework/zend-stdlib": "self.version"
    },
    "suggest": {
        "zendframework/zend-servicemanager": "To support plugin manager support",
        "zendframework/zend-filter": "For value filtering and sanitation",
        "zendframework/zend-validator": "For value validation and errors"
    },

Just some quick notes:

1. I'd get rid of the traits while prototyping. Traits are useful only once you're having lots of duplicate code, and in this case we won't
2. I'd still keep an Input being a Validator + Filter (both optional)
3. An InputFilter should be renamed to InputCollection, and should simply act as an Input on any array|Traversable. That naming also clears up its role.
4. The fact that an Input may be required or not could probably land in the InputCollection, since the input itself doesn't deal with cases where no value at all is passed in.
5. I'd leave validation groups out while prototyping, they really are operations on the collection.
6. +1 for the ValidationResult. That can encapsulate a lot of logic that is currently mixed up with inputs/validators/filters and may as well handle translations or such. It should probably be a FilterResult though, since it doesn't just include validation results, but also original and filtered data. It also allows persistence of validation results.
7. +1 on making Input stateless
8. filterAndValidate is a code smell (just a note: there's an And in your method name, nuff said). Instead, some way of deciding whether filtering or validation goes first should be defined. That's an implementation detail of the filter.

I've already renamed the InputFilter to InputCollection (you can check it here: zendframework/zendframework#4772 (comment)).

Regarding Input stateless, my question is: how can you retrieve the raw value and filtered value if you never store it?

In my refactor, it uses RecursiveIteratorIterator: https://github.com/bakura10/zf2/blob/902416598924a1749096d2026e6e8c02e01c3c4e/library/Zend/InputFilter/InputCollection.php#L317-L336

What we get is only Input, not input collection, therefore the logic of required/not required is handled by the input, not input collection.

Regarding ValidationResult, I'll try to integrate it.

The ValidationResult thing is really not easy at all, because of the recursiveiteratoriterator thing….

@texdc: what happen in case of InputCollection embedded another InputCollection, regarding the ValidationResult ? The problem is that with this new implementation using RecursiveIteratorIterator, what I get are only Input (only leaves). It makes the validation result stuff extremely complicated, and I would need to revert to the old way (ZF2) which is at least 10 times slower.

EDIT : what I don't understand too is that from your code, the "Input" class returns too a ValidationResult. So what a InputCollection / InputFilter would return ? An array of validation result? And what about an input collection containing input collection containing input ? Would it returns nested validation results too? I can't get it.