How to get id of all subcategories from category tree?

Question

Arrays

DB structure. Category Table

id | category_id | title |

Where category_id is the category ID of the parent.



For example, a category with ID 1 has a subcategory, which in turn also has a subcategory with a subcategory.

Please tell me how to get an array with an ID like this:

array('1'=>array('2','3','4'));

Thank you in advance.

Answer 1

In general, I found a solution myself:
CONTROLLER

public function getAllCategories(){
        
        $categories = Category::whereNull('category_id')->with('children')->get();
        
        foreach($categories as $category){
            $cats[$category->id] = $this->getAllChildrenCats($category);
        }

    }

    public function getAllChildrenCats($category, $catsIds = []){

        foreach($category->children as $children){
          
          $catsIds[] = $children->id;
          
          if($children->children){
            $catsIds = $this->getAllChildrenCats($children, $catsIds);
          }
          
        }
                
        return $catsIds; 
  
    }

MODEL

public function children() {
        return $this->hasMany(Category::class, 'category_id')
          			->with('children');
    }