hasOneThrough Laravel Eloquent Relationship

Question

I have 3 tabes categories, sub_categories & products

• category table

---------------------
| id | category_name |
---------------------

• sub_category table

--------------------------------------------
| id | category_id(FK) | sub_category_name |
--------------------------------------------

• product table

-----------------------------------------------------------------
| id | sub_category_id(FK) | product_name | product_description |
-----------------------------------------------------------------

**How do I get product category name using hasOneThrough eloquent relationship ( or using any other relationship). I tried this in product model **

public function category(){
return $this->hasOneThrough(
    Category::class, 
    SubCategory::class
);

}

But it gives error: Unknown column 'sub_categories.product_id'

Answer 1

You can install this external package staudenmeir/belongs-to-through to add the relationship you need.

class Product extends Model
{
    public function subCategory()
    {
        return $this->belongsTo(SubCategory::class);
    }

    public functoin category()
    {
        return $this->belongsToThrough(Category::class, SubCategory::class);
    }
}

class SubCategory extends Model
{
    public functoin category()
    {
        return $this->belongsTo(Category::class);
    }
}

class Category extends Model
{
    public function subCategories()
    {
        return $this->hasMany(SubCategory::class);
    }

    public functoin products()
    {
        return $this->hasManyThrough(Product::class, SubCategory::class);
    }
}

If you need to access Category directly from Product, and want to use laravels functions like $product->category()->attach($category->id) etc, then you need this dependency to achieve that.

If you are ok with doing:

    $product->subCategory->category;
    // or
    $product->subCategory->category()->attach($category->id);

Then you don't need the dependency and you can exclude the category relationship on the Product model.