Laravel eloquent get relation count

Question

I use Laravel 5.3.

I have 2 tables :

Articles
---------
id
cat_id
title

And

Category
---------
id
parent_id
title
         


        

Answer 1

This should work:

$category
->where('categories.parent_id', 0)
->leftJoin('article', 'article.cat_id', '=', 'categories.id')
->select('categories.id', \DB::raw('COUNT(article.id)'))
->groupBy('categories.id')
->get();

The above query will get you category IDs and count of all articles that belong to the category.

After reading your question and comments again, if I understand correctly you want to get the count of all articles that belong to those categories (with parent_id = 0) + the count of articles that belong to sub categories (those with parent_id = (id of some category)).

Now I have no way of testing this easily, but I think something along these lines should work for that.

$category
->where('categories.parent_id', 0)
->leftJoin('article', 'article.cat_id', '=', 'categories.id')
->leftJoin('categories as c2', 'c2.parent_id', '=', 'categories.id')
->leftJoin('article as a2', 'a2.cat_id', '=', 'c2.id')
->select('categories.id', \DB::raw('(COUNT(article.id)) + (COUNT(a2.id)) as count'))
->groupBy('categories.id')
->get();

That beign said, I think you're better of having a column named count in categories and update it each time a new article gets added. For performance.