Validation Tutorial

Memio provides a Validator component that allows us to define Model constraints. It also provides a Linter package, which is a collection of constraints that aims at checking syntax errors and the like:

  • Collection cannot have name duplicates
  • Concrete Object Methods cannot be abstract
  • Contract Methods can only be public
  • Contract Methods cannot be final
  • Contract Methods cannot be static
  • Contract Methods cannot have a body
  • Method cannot be abstract and have a body
  • Method cannot be both abstract and final
  • Method cannot be both abstract and private
  • Method cannot be both abstract and static
  • Object Argument can only default to null

Here's how to ue the linter:

use Memio\Memio\Config\Build;
use Memio\Model\Method;

(new Method('myMethod'))

$linter = Build::linter();
$linter->validate($method); // @throws Memio\Validator\Exception\InvalidModelException

UML class diagram

Providing new Constraints

To add new rules to the validator, we first need to create a new Constraint:


namespace Vendor\Project\Validator\Constraint;

use Memio\Validator\Constraint;
use Memio\Validator\Violation\NoneViolation;
use Memio\Validator\Violation\SomeViolation;

class ArgumentCannotBeScalar implements Constraint
    public function validate($model)
        if (!$model->isObject()) {
            return new SomeViolation(sprintf('Argument "%s" cannot be scalar', $model->getName()));

        return new NoneViolation();

Note: We've named the constraint after its error message. This isn't mandatory, but this way it clearly express its purpose.

We then need to register our rule in an ArgumentValidator:

// ...

use Memio\Validator\ModelValidator\ArgumentValidator;

$argumentValidator = new ArgumentValidator();
$argumentValidator->add(new ArgumentCannotBeScalar());

For each model Memio provides a ModelValidator. When providing Validator with an Argument, it will call ArgumentValidator.

This isn't enough: if we provide a Method to Validator, we'd like it to also check its Arguments. To do so, we need to assemble ModelValidators as follow:

// ...

use Memio\Validator\ModelValidator\CollectionValidator;
use Memio\Validator\ModelValidator\MethodValidator;
use Memio\Validator\ModelValidator\ContractValidator;
use Memio\Validator\ModelValidator\ObjectValidator;
use Memio\Validator\ModelValidator\FileValidator;

$collectionValidator = new CollectionValidator();
$methodValidator = new MethodValidator($argumentValidator, $collectionValidator);
$contractValidator = new ContractValidator($collectionValidator, $methodValidator);
$objectValidator = new ObjectValidator($collectionValidator, $methodValidator);
$fileValidator = new FileValidator($contractValidator, $objectValidator);

Finally, we need to create a validator and register our ModelValidators in it:

// ...
$myValidator = new Validator();

We'll be able to use it like this:


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