Add missing base controller

app/controllers/step_components/base_controller.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module StepComponents
+  class BaseController < ApplicationController
+    before_action :load_step_and_protocol
+    before_action :check_manage_permissions
+
+    private
+
+    def load_step_and_protocol
+      @step = Step.find_by(id: params[:step_id])
+      return render_404 unless @step
+
+      @protocol = @step.protocol
+    end
+
+    def check_manage_permissions
+      render_403 unless can_manage_step?(@step)
+    end
+
+    def create_in_step!(step, new_orderable)
+      ActiveRecord::Base.transaction do
+        new_orderable.save!
+
+        step.step_orderable_elements.create!(
+          position: step.step_orderable_elements.length,
+          orderable: new_orderable
+        )
+      end
+    end
+
+    def render_step_orderable_element(orderable)
+      step_orderable_element = orderable.step_orderable_elements.find_by!(step: @step)
+      render json: step_orderable_element, serializer: StepOrderableElementSerializer, user: current_user
+    end
+  end
+end