mesreleves-php/app/Models/Lieu.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;

class Lieu extends Model
{
    protected $table = 'lieux';

    protected $fillable = ['nom', 'code', 'lieu_parent_id', 'nom_long', 'latitude', 'longitude', 'note'];

    public function parent(): BelongsTo
    {
        return $this->belongsTo(Lieu::class, 'lieu_parent_id');
    }

    public function enfants(): HasMany
    {
        return $this->hasMany(Lieu::class, 'lieu_parent_id');
    }

    public function sections(): HasMany
    {
        return $this->hasMany(Section::class);
    }

    public function calculerNomLong(): string
    {
        $noms = [$this->nom];
        $parent = $this->parent;
        while ($parent) {
            $noms[] = $parent->nom;
            $parent = $parent->parent;
        }
        return implode(', ', $noms);
    }

    protected static function booted(): void
    {
        $recalc = function (Lieu $lieu) {
            $lieu->nom_long = $lieu->calculerNomLong();
        };

        static::creating($recalc);
        static::updating($recalc);
    }
}