Question

I have a code structure like this:

if params[:one] && params[:two]
  object = Something.where(:one => params[:one], :two => params[:two])
elsif params[:one]
  object = Something.where(:one => params[:one])
elsif params[:two]
  object = Something.where(:two => params[:two])
else
  object = Something.all
end

Basically, two optional parameters in the URL that filter the query to be made. Can this be cleaner?

Answer 1

I’d write:

objects = Something.where(params.slice(:one, :two))

Notes:

1. Usually an empty param is also to be considered as non-existing. In this case: Something.where(params.slice(:one, :two).select { |k, v| v.present? }).

2. Strange as it may look, in your snippet you should write object = if ..., it’s far more idiomatic being Ruby a language where conditionals are expressions and not statements.

3. Don’t call all as a no-op, you don’t have a ActiveRecord::Relation (cool) anymore, but a Array (not so cool). where({}) is perfectly fine.

4. Naming is very important! If you see object you think “single element” (which is not true here), if you see objects you think “collection”.

5. If the param keys does not match DB columns: a lot of ways to do it, for example:

   pairs = {:x => :db_x, :y => db_y}.map { |k, v| [v, params[k]] if params[k] }]
   Something.where(Hash[pairs.compact])
   

Or being just two attributes:

attrs = {:db_one => params[:one], :db_two => params[:two]}
Something.where(attrs.select { |k, v| v })