Tagged union FormRequest Rule Validation

[brianferri]

Track: #54946

As the title suggests, the feature would implement Tagged Unions in a form request context, a possible way would be to follow the OpenAPI Specification for Discriminator Objects

currently, the way I've found to do something ""Similar"", but Isn't right, is the following:

<?php

namespace App\Http\Requests;

use App\Util\OpenAPIGenerator;
use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Validation\Rule;
use OpenAPI\Client\Model\ModelServices;
use OpenAPI\Client\Model\Params;

class StoreWorkflowServices extends FormRequest
{
    /**
     * Get the validation rules that apply to the request.
     *
     * @return array<string, \Illuminate\Contracts\Validation\ValidationRule|array<mixed>|string>
     */
    public function rules(): array
    {
        /** @var Params[] */
        $paramsRules = [];
        $modelServiceValues = array_map(fn($case) => $case->value, ModelServices::cases());

        foreach ($modelServiceValues as $modelService) {
            $modelClass = '\\OpenAPI\\Client\\Model\\' . $modelService . 'Params';
            /** @var Params */
            $params = new $modelClass();
            $paramServices = $params->getServiceAllowableValues();
            $formats = $params->openAPIFormats();
            foreach ($params->openAPITypes() as $key => $type) {
                $paramsRules["params.$modelService.$key"] = match ($key) {
                    Params::DISCRIMINATOR => ['required', Rule::in($paramServices)],
                    default => OpenAPIGenerator::mapTypeToRule($type, $formats[$key])
                };
            }
        }

        return array_merge([
            Params::DISCRIMINATOR => ['required', Rule::enum(\OpenAPI\Client\Model\ModelServices::class)]
        ], $paramsRules);
    }
}

Using the PHPNextGen generator from OpenAPIGenerator

Example: OpenAPITools/openapi-generator#20343

Untitled-1.json
https://dpaste.org/k2Qoe

openapitools.config.yml

generatorName: php-nextgen
outputDir: core/client
globalProperties:
  models: ""
  apis: ""
  supportingFiles: "README.md,ApiException.php,Configuration.php,HeaderSelector.php,ObjectSerializer.php,ModelInterface.php"

openapi-generator-cli generate -i Untitled-1.json -c openapitools.config.yml

[brianferri]

Update on potential implementation:

<?php

namespace App\Http\Requests;

use App\Util\OpenAPIGenerator;
use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Validation\Rule;
use OpenAPI\Client\Model\ModelServices;
use OpenAPI\Client\Model\Params;

class StoreWorkflowServices extends FormRequest
{
    public static function list(): array
    {
        $modelServiceValues = array_map(fn($case) => $case->value, ModelServices::cases());
        $classCases = [];
        foreach ($modelServiceValues as $modelService) {
            $paramsRules = [];
            $modelClass = '\\OpenAPI\\Client\\Model\\' . $modelService . 'Params';
            /** @var Params */
            $params = new $modelClass();
            $formats = $params->openAPIFormats();
            foreach ($params->openAPITypes() as $key => $type) {
                $paramsRules[$key] = match ($key) {
                    Params::DISCRIMINATOR => ['required', Rule::in($params->getServiceAllowableValues())],
                    default => OpenAPIGenerator::mapTypeToRule($type, $formats[$key])
                };
            }
            array_push($classCases, $paramsRules);
        }
        return $classCases;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array<string, \Illuminate\Contracts\Validation\ValidationRule|array<mixed>|string>
     */
    public function rules(): array
    {
        return [
            Params::DISCRIMINATOR => ['required', Rule::enum(\OpenAPI\Client\Model\ModelServices::class)],
            'params' => ['required', Rule::in($this::list())] // <-- This won't work for obvious reasons
        ];
    }
}

Currently Rule::in is used to validate if a body parameter is in a set of strings. could the logic be extended to objects/nested data in terms of instanceof or using NestedRule? a more intuitive name would then be oneOf

[brianferri]

Prototype

<?php

use Closure;
use Illuminate\Contracts\Validation\ValidationRule;
use Illuminate\Support\Facades\Validator;

class OneOf implements ValidationRule
{
    /** @var ValidationRule[] */
    private array $rules;

    /** @param ValidationRule[] $rules */
    public function __construct(array $rules)
    {
        $this->rules = $rules;
    }

    /**
     * Run the validation rule.
     *
     * @param  \Closure(string, ?string=): \Illuminate\Translation\PotentiallyTranslatedString  $fail
     */
    public function validate(string $attribute, mixed $value, Closure $fail): void
    {
        if (!is_array($value)) {
            $fail("The :attribute field must be an array.");
            return;
        }

        foreach ($this->rules as $ruleSet) {
            $validator = Validator::make($value, $ruleSet);
            // At least one type is valid, so pass validation
            if ($validator->passes()) return;
        }

        $fail("The :attribute field does not match any of the allowed structures.");
    }
}

Which in the context of my use case:

// ...
    public function rules(): array
    {
        return [
            Params::DISCRIMINATOR => ['required', Rule::enum(\OpenAPI\Client\Model\ModelServices::class)],
            'params' => ['required', new OneOf($this::list())]
        ];
    }
// ...