Ruby on Rails: where returning nil

Question

In my app I'm obtaining a certain category, and I'm filtering the associated items based on their name. The following code should be pretty clear:

categories = Category.where(:id => params[:category_id]).includes(:items).where("lower(items.name) like ?", "%#{params[:keywords].downcase}%")

However, if the name filter excludes all the items, the categories object returned by where is nil. Is this the expected behaviour? How can I get the category even either items exist or not?

Answer 1

The easiest way might be to just split the query:

@category = Category.find(params[:category_id])
@items = @category.items.where("lower(items.name) like ?", "%#{params[:keywords].downcase}%")

Based on your code it seems like category_id references only 1 category so I've changed it to singular.

Answer 2

You should look into doing an OUTER JOIN against the items table which will give you categories regardless of whether or not their items meet the name filter.