Laravel Virgin: Access inverse model relationship in a model's mutator that participate in the relationship - database

Question

In my logic I have these tables:
Table Grid:
id PK
width INT
height INT
Table Rover:
id pk
grid_pos_x UNSIGNED INT
grid_pos_y UNSIGNED INT
grid_id UNSINGED BIGINT
NOTE: I kept minimal in order to be more explanatory, for full table specs look on migration scripts below.
And I use the following migration script to create the schemas:
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateGridTable extends Migration
{
/**
* Run the migrations.
*
* #return void
*/
public function up()
{
Schema::create('grid', function (Blueprint $table) {
$table->bigIncrements('id');
$table->unsignedInteger('width');
$table->unsignedInteger('height');
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::dropIfExists('grid');
}
}
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateRoverTable extends Migration
{
/**
* Run the migrations.
*
* #return void
*/
public function up()
{
Schema::create('rover', function (Blueprint $table) {
$table->bigIncrements('id');
$table->bigInteger('grid_id')->unsigned();
$table->string('command');
$table->foreign('grid_id')->references('id')->on('grid');
$table->smallInteger('last_commandPos')->unsigned()->default(0);
$table->smallInteger('grid_pos_x')->unsigned();
$table->smallInteger('grid_pos_y')->unsigned();
$table->enum('rotation', App\Constants\RoverConstants::ORIENTATIONS);
$table->string('last_command');
Schema::enableForeignKeyConstraints();
});
}
/**
* Reverse the migrations.
*
* #return void
*/
public function down()
{
Schema::dropIfExists('rover');
}
}
And I try to model the table rover with the following model:
namespace App\Model;
use Illuminate\Database\Eloquent\Model;
use App\Model\Grid;
class Rover extends Model
{
/**
* Table Name
*/
protected $table='rover';
public function grid()
{
return $this->belongsTo(Grid::class);
}
public function setGridPosXValue($value)
{
}
public function setGridPosYValue($value)
{
}
}
And in a similar fashion the Grid model as well:
namespace App\Model;
use Illuminate\Database\Eloquent\Model;
use App\Model\Rover;
class Grid extends Model
{
/**
* Table Name
*/
protected $table='grid';
public function rovers()
{
return $this->hasMany(Rover::class);
}
}
What I want to achieve is to access the width and height attributes from the Grid in order to check whether the grid_pos_x and grid_pos_y are smaller from the width and height using the methods setGridPosXValue and the setGridPosYValue respectively.
Do you know how to do that?

Answer 1

Looks like you have a one to many relationship setup here: https://laravel.com/docs/5.8/eloquent-relationships#one-to-many
To get the grid for a rover you can access it in multiple ways:
Directly:
$width = $Rover->grid->width;
$height = $Rover->grid->height;
With the builder methods:
$Grid = $Rover->grid()->first();
$width = $Grid->width;
$height = $Grid->height;