False positive for ActionControllerFlashBeforeRender

[thestelz]

Sorry if this is a duplicate. I was trying to make sure all possible fixes were released before adding this bug report.

We get a Rails/ActionControllerFlashBeforeRender error when the if block does a redirect_to and return before the render block (see below for setup).

---

Expected behavior

No error should be triggered for the cop Rails/ActionControllerFlashBeforeRender.

Actual behavior

It triggers Rails/ActionControllerFlashBeforeRender when it shouldn't.

Steps to reproduce the problem

I have an admin controller:

# frozen_string_literal: true

module Admin
  class ListingAttributeTypesController < ApplicationController
    before_action :find_listing_attr_type, only: %i[edit update]

    # :nodoc:
    def index
      @listing_attribute_types = ListingAttributeType.ord_inactive.ord_name
    end

    # :nodoc:
    def new
      @listing_attribute_type = ListingAttributeType.new

      render('form')
    end

    # :nodoc:
    def create
      @listing_attribute_type = ListingAttributeType.new(listing_attr_type_params)

      if @listing_attribute_type.save
        flash[:success] = 'Listing attribute type saved!'

        redirect_to(admin_listing_attribute_types_path)

        return
      end

      render('form', status: :unprocessable_entity)
    end

    # :nodoc:
    def edit
      render('form')
    end

    # :nodoc:
    def update
      if @listing_attribute_type.update(listing_attr_type_params)
        flash[:success] = 'Listing attribute type updated!'

        redirect_to(admin_listing_attribute_types_path)

        return
      end

      render('form', status: :unprocessable_entity)
    end

    private

      # Return safe form params
      #
      # @return [ActionController::Parameters]
      #
      def listing_attr_type_params
        params.require(:listing_attribute_type).permit(:id, :name, :inactive)
      end

      # Finds the listing attribute type
      #
      # @return [void]
      #
      def find_listing_attr_type
        @listing_attribute_type = ListingAttributeType.find(params[:id])
      end
  end
end

I then run rubocop and get the following:

Offenses:

app/controllers/admin/listing_attribute_types_controller.rb:24:9: C: [Correctable] Rails/ActionControllerFlashBeforeRender: Use flash.now before render.
        flash[:success] = 'Listing attribute type saved!'
        ^^^^^
app/controllers/admin/listing_attribute_types_controller.rb:42:9: C: [Correctable] Rails/ActionControllerFlashBeforeRender: Use flash.now before render.
        flash[:success] = 'Listing attribute type updated!'
        ^^^^^

RuboCop version

# ruby -v
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [aarch64-linux]

# rubocop -V
1.42.0 (using Parser 3.2.0.0, rubocop-ast 1.24.1, running on ruby 3.1.2) [aarch64-linux]
  - rubocop-rails 2.17.4

# bundle exec rubocop -V
1.42.0 (using Parser 3.2.0.0, rubocop-ast 1.24.1, running on ruby 3.1.2) [aarch64-linux]
  - rubocop-rails 2.17.4

[arsduo]

👍 Just encountered the same problem. @thestelz thanks for filing this!

[tagliala]

Hi, I'm not sure it is the same issue, but I have this reduced test case:

# frozen_string_literal: true

class ApplicationController < ActionController::Base
  def create
    @user = User.new(user_params)

    if @user.valid?
      if SomeService.call(@user)
        flash[:success] = t('.flash.success')
        redirect_to @user
      else
        @user.errors.add(:base, 'an error')
        render :new, status: :unprocessable_entity
      end
    else
      render :new, status: :unprocessable_entity
    end
  end
end

rubocop --only Rails/ActionControllerFlashBeforeRender app/controllers/application_controller.rb 
Inspecting 1 file
C

Offenses:

app/controllers/application_controller.rb:9:9: C: [Correctable] Rails/ActionControllerFlashBeforeRender: Use flash.now before render.
        flash[:success] = t('.flash.success')
        ^^^^^

1 file inspected, 1 offense detected, 1 offense autocorrectable

[koic]

Yeah, that is the same problem as the subject. I've opened #937 to resolve the issues.