Before action callback in Rails has support to add conditions like if and unless. The callback is executed only if the conditions evaluate to true. But, skip_before_action callback does not support conditionals. In this article we will learn how to skip certain action based on some condition.

before_action callback

As, before_action callback supports conditional. Let’s say, we have a ProductsController as given below.

class ProductsController < ApplicationController
  def index
  end
end

Now, let’s say, we want to run some code before index action based on some condition.

class ProductsController < ApplicationController

  before_action :execute_this, if: :this_is_true?

  def index
  end

  private

  def execute_this
    # Some before action condition to execute
  end

  def this_is_true?
    Rails.logger.debug "This is being executed before #{params[:action]}"
    true
  end
end

this_is_true method will be executed before every action of the controller. As, the method returns true, the controller action will get executed.

skip_before_action callback

skip_before_action callback supports callbacks (methods) to be skipped. It supports two options.

• only - The callback should be run only for this action.
• except - The callback should be run for all actions except this action.

As before_action callback supports conditional options like if? and unless, people tend to assume skip_before_action would support these two conditionals. But, that’s not the case.

skip_before_action with condition (workaround)

Let’s take the same example as given above to skip before action for some condition.

It can be written as given below.

class ProductsController < ApplicationController

  skip_before_action :execute_this
  before_action :execute_this, unless: :this_is_true?

  private

  def execute_this
    # Some before action condition to execute
  end

  def this_is_true?
    Rails.logger.debug "This is being executed before #{params[:action]}"
    true
  end

end

Interpretation and conclusion

• execute_this callback will be skipped by default.
• execute_this callback will be execute if this_is_true? returns false.

In order to achive conditional on skip_before_action, add the negative conditional on before_action. Provided skip_before_action is added before before_action.