[11.x] Add Recursive Hierarchy Root ID Retrieval Method for Model getHierarchyRootId

[pandiselvamm]

Add method getHierarchyRootId(string $parentFieldName = 'parent_id') to get the root ID of the hierarchy for the given model.

Category Table

ID	Name	Parent ID
1	Electronics	NULL
2	Laptops	1
3	Gaming Laptops	2
4	Ultrabooks	2
5	Smartphones	1
6	Accessories	NULL
7	Headphones	6

Scenario: Finding the root parent of id = 3 (Gaming Laptops)

1️⃣ Gaming Laptops (id=3) → Parent ID = 2 (Laptops)
2️⃣ Laptops (id=2) → Parent ID = 1 (Electronics)
3️⃣ Electronics (id=1) → Parent ID = NULL (Root Parent Found)

Final Output: 1 (Electronics)

Usage:

---

class Category extends Model
{
    use HasFactory, HasHierarchy;

    protected $fillable = ['name', 'parent_id'];
}

$rootId = Category::find(3)->getHierarchyRootId();
echo "Root Parent ID: " . $rootId;

[shaedrich]

Wouldn't getHierarchyRootId() be more intuitive?