Laravel 5 sub-query for each result row

Question

I am relatively new to Eloquent and Laravel 5 and am using the query builder to create a dynamic query for categories dependant on what variables have been supplied to the function.

In my categories table there is a column called 'parent_id' which indicates whether the category is a sub-category or not. Here is my function so far:

public static function filterCategory($vars) {

        $query = Category::query();

        if((array_key_exists('order_by', $vars)) && (array_key_exists('order', $vars))) {
            $query = $query->orderBy($vars['order_by'], $vars['order']);
        }

        if(array_key_exists('product', $vars)) {
            $query = $query->whereHas('products', function($q) use ($vars){
                return $q->where('id', $vars['product']);
            });
        }

        if(array_key_exists('sub_cats', $vars)) {
            $query = $query->with('subCategories');
        }

        return $query->get();
    }

I have created a function on the Category model called getChildren which looks like this:

public function subCategories() {
    return $this->hasMany('App\Category', 'parent_id', 'id');
}

What I want to be able to do is when my category function is called to return categories, I need a sub-query to be executed for each row which will create a sub-array on the results object containing all categories which have the id of the current category as it's 'parent_id'. I want this returned:

[
  {
    "id": "1",
    "name": "Dr. Ben Becker DDS",
    "description": "Et atque illo ut architecto. Blanditiis laboriosam hic sed quia. Aperiam quis totam distinctio.",
    "created_at": "1981-04-07 22:04:40",
    "updated_at": "2009-02-26 19:53:09",
    "parent_id": null,
    "subcategories" : {
         //results in here
     }
  },
  {
    "id": "2",
    "name": "Ms. Winona Lehner",
    "description": "Repudiandae nostrum repellendus nulla delectus saepe sapiente ipsam. Delectus voluptatem quis excepturi. Tenetur nostrum et cum quia. Fugiat totam sed dicta totam illo ut dolores.",
    "created_at": "2002-01-13 13:42:18",
    "updated_at": "1981-10-25 11:39:14",
    "parent_id": null,
    "subcategories" : {
         //results in here
     }
  },

Now, this would be simple enough for me to do in vanilla PHP and MYSQL but I don't know how this would be implemented in Laravel with the Eloquent querybuilder.

**UPDATE So I have the subcategories returning but unfortunately not correctly. Here is my output:

[
  {
    "id": "1",
    "name": "Dr. Ben Becker DDS",
    "description": "Et atque illo ut architecto. Blanditiis laboriosam hic sed quia. Aperiam quis totam distinctio.",
    "created_at": "1981-04-07 22:04:40",
    "updated_at": "2009-02-26 19:53:09",
    "parent_id": null,
    "sub_categories": [
      {
        "id": "3",
        "name": "Dr. Manuel Medhurst",
        "description": "Pariatur ut corporis quas sequi dolor totam. Nisi ad amet velit reiciendis voluptates dolore aperiam. Impedit perferendis et a.",
        "created_at": "1998-09-20 07:40:23",
        "updated_at": "2002-04-01 18:41:24",
        "parent_id": "1"
      },
      {
        "id": "4",
        "name": "Lee Monahan",
        "description": "Nihil qui quod voluptatem non accusamus voluptas. Non et quae velit delectus consequatur vel. Qui totam non rerum sunt nisi soluta sequi. Consequatur eaque quia delectus qui assumenda.",
        "created_at": "2014-11-24 06:31:10",
        "updated_at": "1996-03-28 18:58:55",
        "parent_id": "1"
      },
      {
        "id": "5",
        "name": "Miller Osinski",
        "description": "Itaque et sed voluptatem earum nulla eligendi tenetur. Et velit ut voluptas similique. Autem rerum sapiente voluptatibus optio esse qui sit et. Alias eligendi aut quibusdam inventore.",
        "created_at": "2011-10-08 18:16:56",
        "updated_at": "1996-09-29 16:29:37",
        "parent_id": "1"
      }
    ]
  },
  {
    "id": "3",
    "name": "Dr. Manuel Medhurst",
    "description": "Pariatur ut corporis quas sequi dolor totam. Nisi ad amet velit reiciendis voluptates dolore aperiam. Impedit perferendis et a.",
    "created_at": "1998-09-20 07:40:23",
    "updated_at": "2002-04-01 18:41:24",
    "parent_id": "1",
    "sub_categories": []
  },
  {
    "id": "4",
    "name": "Lee Monahan",
    "description": "Nihil qui quod voluptatem non accusamus voluptas. Non et quae velit delectus consequatur vel. Qui totam non rerum sunt nisi soluta sequi. Consequatur eaque quia delectus qui assumenda.",
    "created_at": "2014-11-24 06:31:10",
    "updated_at": "1996-03-28 18:58:55",
    "parent_id": "1",
    "sub_categories": []
  },
  {
    "id": "5",
    "name": "Miller Osinski",
    "description": "Itaque et sed voluptatem earum nulla eligendi tenetur. Et velit ut voluptas similique. Autem rerum sapiente voluptatibus optio esse qui sit et. Alias eligendi aut quibusdam inventore.",
    "created_at": "2011-10-08 18:16:56",
    "updated_at": "1996-09-29 16:29:37",
    "parent_id": "1",
    "sub_categories": []
  },
  {
    "id": "2",
    "name": "Ms. Winona Lehner",
    "description": "Repudiandae nostrum repellendus nulla delectus saepe sapiente ipsam. Delectus voluptatem quis excepturi. Tenetur nostrum et cum quia. Fugiat totam sed dicta totam illo ut dolores.",
    "created_at": "2002-01-13 13:42:18",
    "updated_at": "1981-10-25 11:39:14",
    "parent_id": null,
    "sub_categories": []
  }
]

At first this looked correct but in my table category 1 only has 1 child (category 4) and category 2 should only 2 children (rows 3 and 5). It would seem that all of these sub-categories are being placed incorrectly into the subcategories array of row 1?

Thanks

Answer 1

Add a relation in your Category model to itself like this:

public function subcategories()
{
    return $this->hasMany('App\Category', 'parent_id', 'id');
}

Change your Category model namespace if it's not App.

Then you'll be able to query them like this:

$categories = Category::with('subcategories')->get();

If you need you can also group by the parent_id to have them arranged: $categories->groupBy( 'parent_id' )->toJson();