php - How to get two arrays of obiects by one column -

hi have on table categories foreign key herself parent_id same id in table. want 2 arrays of objects. first categories

parent_id=0

and second subcategories. dont know how can catch subcategories. have this:

$category= category::where('parent_id', '=', 0)->get(); dd($category[0]['id']); $subcategory= category::where('parent_id', '=', (($category[0]['id']??))); 

first $category shouild return me array of categories , second array subcategories need adjust id of each object of array $category each subcategory array. possible or there other ways?

if define model relations correctly can categories , subcategories in nicer way.

first define relations:

class category extends model {   public function parent() {     return $this->belongsto(category::class);   }    public function subcategories() {    }  return $this->hasmany(category::class, 'parent_id'); } 

you can get parent categories subcategories following way:

$parents = category::whereparentid(0)->with('subcategories')->get(); 

this give list of parent categories, each of them have subcategories property store subcategories. can traverse them in following way:

foreach ($parents $parent) {   printf("parent category %s\n", $parent->name);    foreach ($parent->subcategories $subcategory) {     printf("subcategory %s\n", $subcategory->name);   } } 

small suggestion: make parent_id nullable , store null parent categories instead of 0, 0 not correct category id.