Laravel Lighthouse GraphQL validation based on related model - laravel

Question

Using Laravel Lighthouse GraphQL, i would like to validate a value in one model so that it always matches the value in a related model.
In this case a Program has a year_id and a Category also has a year_id. I want to validate that the Program and the Category use the same year_id.
The GraphQL Schema looks like this:
input CreateCategory {
year_id: ID!
name: String!
}
input CreateProgram {
year_id: ID!
name: String!
category: CreateCategoryRelation
}
input CreateCategoryRelation {
connect: ID
}
Now if I create a Category with year_id: 1 (return Category id=1):
mutation {
createCategory(input:{
year_id: 1
name: "category in year 1"
}) {
name
id
}
}
And then try to create a Program with year_id: 2 related to the new Category
mutation {
createProgram(input:{
year_id: 2
name: "Program in year 2"
category: {
connect: 1
}
}) {
id
name
}
}
I would like the validation so fail with a message like "You cannot create a Program in a different year as it's Category!"
So far I could not find a way to validate based on any value in another model.
How can I do this?

Answer 1

Thanks to the answer from Enzo Notario, I found a solution.
In case others would like more details on how you could (I'm sure this can be done prettier) write your own validation, here is my code:
type Mutation {
createProgram(input: CreateProgram! #spread): Program! #create #yearValidation
}
file App/GraphQL/Directives/YearValidationDirective.php:
<?php
namespace App\GraphQL\Directives;
use App\Rules\SameYear;
use Illuminate\Support\Facades\DB;
use Nuwave\Lighthouse\Schema\Directives\ValidationDirective;
class YearValidationDirective extends ValidationDirective
{
/**
* List of all relations that should be checked for having the same year
*/
private $relations = [
'category' => true
];
/**
* Name of the directive.
*
* #return string
*/
public function name(): string
{
return 'yearValidation';
}
/**
* #return mixed[]
*/
public function rules(): array
{
if (isset($this->args['year_id'])) {
// year_id is given, get it
$year_id = $this->args['year_id'];
} else {
// year_id not given, get it from the model
$id = $this->args['id'];
$fieldName = $this->resolveInfo->fieldName; // "updateTableName"
$tableName = substr($fieldName, 6);
$year_id= DB::table($tableName)->findOrFail($id)->year_id;
}
$relationFields = [];
foreach($this->args as $field => $arg) {
if (is_array($arg) && isset($this->relations[$field])) {
$relationFields[$field] = [new SameYear($year_id)];
}
}
return $relationFields;
}
}
File App/Rules/SameYear.php:
<?php
namespace App\Rules;
use Illuminate\Support\Facades\DB;
use Illuminate\Contracts\Validation\Rule;
class SameYear implements Rule
{
protected $year_id;
protected $found_year_id;
protected $tableName;
protected $connect;
/**
* Create a new rule instance.
*
* #return void
*/
public function __construct($year_id)
{
$this->year_id = $year_id;
}
/**
* Determine if the validation rule passes.
*
* #param string $attribute
* #param mixed $value
* #return bool
*/
public function passes($attribute, $value)
{
$this->connect = $value['connect'];
$this->tableName = ucfirst($attribute);
$this->found_year_id = DB::table($this->tableName)->find($this->connect)->year_id;
return intval($this->found_year_id) === intval($this->year_id);
}
/**
* Get the validation error message.
*
* #return string
*/
public function message()
{
return "Year_id's must be the same! $this->tableName (id: $this->connect) must have year_id: $this->year_id (found: $this->found_year_id)";
}
}
This does the job for me.

Answer 2

You could make your own validation with https://lighthouse-php.com/4.7/security/validation.html#validate-fields