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

Question

Hi i have on table with categories with foreign key to herself where parent_id is the same that id in this table. I want to get two arrays of objects. First with categories where
parent_id=0
and second with subcategories. But I dont know how can I catch this subcategories. I 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 and second array with subcategories i need adjust id of each object of array $category to each subcategory array. Is it possible or there are other ways?

Answer 1

If you define your model relations correctly you can get categories and their subcategories in a much nicer way.
First define the 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 now get all parent categories with their subcategories the following way:
$parents = Category::whereParentId(0)->with('subcategories')->get();
This will give you list of all parent categories, each of them will have subcategories property that will store all subcategories. You can traverse them in the following way:
foreach ($parents as $parent) {
printf("Parent category %s\n", $parent->name);
foreach ($parent->subcategories as $subcategory) {
printf("Subcategory %s\n", $subcategory->name);
}
}
Small suggestion: make your parent_id nullable and store NULL for parent categories instead of 0, as 0 is not a correct category ID.