Convert string array to object with true/false flags

Question

Currently a filter parameter of a GET request is used to designate items' categories that will be requested from database and displayed.

The parameter contains comma delimited string - each string id for each category: filter=complete,inwork,cancelled,ycancelled.

I want to get a Ruby object with corresponding attributes that will be true or false dependent on string id presence in filter parameter. Current implementation is as follows:

filter = params[:filter].split(',') rescue []
fopt = OpenStruct.new(Hash[%w(complete inwork cancelled ycancelled).map {|fo| [fo.to_sym, filter.include?(fo)]}])

Could this be rewritten in shorter way?

Answer 1

Some notes:

• Don't use a catch-all rescue, bad practice.

• Don't write lines so long, they are hard to read.

• Move all logic to models.

I'd write (in some model, not in a controller):

allowed_keys = %w(complete inwork cancelled ycancelled)
params_keys = params.fetch(:filter, "").split(',').map(&:strip).to_set
filter_attributes = allowed_keys.map { |k| [k.to_sym, params_keys.include?(k)] }.to_h
fopt = OpenStruct(filter_attributes)

Answer 2

Code looks great to me. Here is a Rubocop-clean version with one change:

def fopt
  filter = (params[:filter] || '').split(',')
  OpenStruct.new(Hash[
    %w(complete inwork cancelled ycancelled).map do |fo|
      [fo.to_sym, filter.include?(fo)]
    end
  ])
end

Note the Rubocop rule to avoid rescue in its modifier form.