Rails ActiveRecord .where method doesn't execute SQL query - ruby-on-rails

Question

I've written a set of Rails search methods that takes an optional parameter to define the rigor of the search. The core method is as follows:
class Participant < ActiveRecord::Base
def self.matches(field_name, param, rigor = 'exact')
where("lower(#{field_name}) like ?", "#{param}") if rigor == 'exact'
where("lower(#{field_name}) like ?", "%#{param}%") if rigor == 'soft'
end
end
I'm getting this result:
[1] pry(main)> >> Participant.matches('last_name', 'Goodman', 'soft')
Participant.matches('last_name', 'Goodman', 'soft')
Participant Load (5.1ms) SELECT "participants".* FROM "participants" WHERE (lower(last_name) like '%Goodman%')
=> [#<Participant:0x007fc6fecee8d0
id: 17,
first_name: "Harris",
last_name: "Goodman",
gender: 0,
birthdate: nil,
city: nil,
state_code: "CA",
email: nil,
phone: nil,
created_at: Wed, 30 Mar 2016 11:18:33 MDT -06:00,
updated_at: Wed, 30 Mar 2016 11:18:33 MDT -06:00,
created_by: 1,
updated_by: 1,
country_code: "US",
user_id: nil>]
[2] pry(main)> >> Participant.matches('last_name', 'Goodman', 'exact')
Participant.matches('last_name', 'Goodman', 'exact')
=> nil
Rails doesn't seem to be firing the SQL query when the 'exact' parameter is passed.
I've also tried = in place of like but get the same result. Worked on this for over an hour with no success. Any ideas would be welcome.
EDIT: OK, so a bit of refactoring solves the problem:
def self.matches(field_name, param)
where("lower(#{field_name}) like ?", "%#{param}%")
end
def self.exact_matches(field_name, param)
where("lower(#{field_name}) like ?", "#{param}")
end
I would still like to know why this works but the more elegant earlier solution does not.

Answer 1

Every function/method returns the last evaluated value.
In your case it's
where("lower(#{field_name}) like ?", "%#{param}%") if rigor == 'soft'
which returns nil if rigor is not 'soft'.
So adding a return should doing what you want:
def self.matches(field_name, param, rigor = 'exact')
return where("lower(#{field_name}) like ?", "#{param}") if rigor == 'exact'
where("lower(#{field_name}) like ?", "%#{param}%") if rigor == 'soft'
end