Translate from CodeIgniter Active Record model to Laravel Eloquent - codeigniter

Question

I am a CodeIgniter trying to adopt Laravel, however, I have been having a lot of problems understanding how to use Eloquent.
I suspect that if I could figure out how to translate some of my CodeIgniter Model methods to Laravel Eloquent I might be able to get on better. Hopefully, this will help others with the same problem.
Could anybody please rewrite the following from CodeIgniter to Eloquent:
public function get_products($product_id = NULL, $category_id = NULL, $limit = NULL)
{
$this->db->select('*, product.id AS product_id');
$this->db->from('product');
$this->db->join('product_unit', 'product.source_unit_id = product_unit.id', 'left');
$this->db->join('stock_levels', 'product.stock_level_id = stock_levels.id', 'left');
$this->db->join('categories', 'product.category_id = categories.cat_id', 'left');
if(isset($product_id)) {
$this->db->where('product.id', $product_id);
}
if(isset($category_id)) {
$this->db->where('product.category_id', $category_id);
}
if(isset($limit)) {
$this->db->limit($limit);
}
#$this->db->order_by('categories.cat_name', 'ASC');
$this->db->order_by('categories.cat_name', 'ASC');
$this->db->order_by('product.name', 'ASC');
$query = $this->db->get();
return $query->result_array();
}

Answer 1

Here's an approximate version of your query, there should be some things to tweak, but I hope you get the idea:
public function get_products($product_id = NULL, $category_id = NULL, $limit = NULL)
{
$query = Product::leftJoin('product_unit', 'source_unit_id', '=', 'product_unit.id')
->leftJoin('stock_levels', 'stock_level_id', '=', 'stock_levels.id')
->leftJoin('categories', 'category_id', '=', 'categories.cat_id');
if(isset($product_id)) {
$query->where('product.id', $product_id);
}
if(isset($category_id)) {
$query->where('product.category_id', $category_id);
}
if(isset($limit)) {
$query->limit($limit);
}
#$this->db->order_by('categories.cat_name', 'ASC');
$query->orderBy('categories.cat_name', 'ASC');
$query->orderBy('product.name', 'ASC');
dd( $query->toSql() ); /// this line will show you the sql generated and die // remove it to execute the query
return $query->get()->toArray();
}