CODEWITHSUNDEEP
ruby-on-rails
perseverance
perseverance

Reputation: 6622

How do you create a callback with an if statement for multiple changed fields in Ruby on Rails?

I would like to create a before_save callback that only gets run if there have been changes to any (but not necessarily all) of the three fields (street, city, state). How do you do this? Thanks

user.rb

class User
  before_save :run_test_method, :if => street_changed?

  ...
end

Upvotes: 9

Views: 5089

Answers (3)

Aurelien
Aurelien

Reputation: 369

You can also use a lambda:

before_save :run_test_method, if: ->(u) {u.street_changed? || u.something_changed? || u.something_else_changed?}

Upvotes: 1

Chris Salzberg
Chris Salzberg

Reputation: 27374

You can do it in one line using a Proc:

class User
  before_save :run_test_method, :if => Proc.new { |u| u.street_changed? || u.city_changed? || u.state_changed? }

  ...
end

Upvotes: 12

tristanm
tristanm

Reputation: 3357

Option One

You could create a method like:

def ok_to_run_test_method?
  street_changed? || something_changed? || something_else_changed?
end

and then use:

before_save :run_test_method, :if => :ok_to_run_test_method?

Note how :ok_to_run_test_method? is a symbol. Not sure if it was a typo or not but in your question you are actually calling a class method street_changed?.

Option Two

Modernise your callbacks a little bit and use the block-style syntax:

before_save do
  if street_changed? || something_changed? || something_else_changed?
    # whatever you currently have in #run_test_method
  end
end

Upvotes: 15

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