DB restructure, print page

app/models/id_card/field_exception_item.rb

@@ -0,0 +1,27 @@
+module IdCard
+    class ExceptionItem < ApplicationRecord
+        belongs_to :exception
+        belongs_to :network_logo, optional: true
+        belongs_to :provider_section, optional: true
+
+        validate :only_one_exception_field_present
+
+        FIELDS_TO_VALIDATE = [:field_value, :card_logo_file_id, :card_provider_id].freeze
+
+        VALID_FIELD_NAMES = ['network_logo', 'provider_section', 'effective_date']
+
+        validates :field_name, inclusion: { in: VALID_FIELD_NAMES,
+                                        message: "%{value} is not a valid Id Card Field Name" }
+
+
+        private
+
+        def only_one_exception_field_present
+            present_fields = FIELDS_TO_VALIDATE.count { |field| self[field].present? }
+
+            if present_fields != 1
+                errors.add(:base, "Only one exception field can be present at a time")
+            end
+        end
+    end
+end