enable custom workflows for issue relations

app/models/custom_workflow.rb

@@ -21,11 +21,11 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 class CustomWorkflow < ActiveRecord::Base
-  OBSERVABLES = [:issue, :issue_attachments, :user, :attachment, :group, :group_users, :project, :project_attachments,
+  OBSERVABLES = [:issue, :issue_relation, :issue_attachments, :user, :attachment, :group, :group_users, :project, :project_attachments,
                  :wiki_content, :wiki_page_attachments, :time_entry, :version, :shared]
   PROJECT_OBSERVABLES = [:issue, :issue_attachments, :project, :project_attachments, :wiki_content, :wiki_page_attachments, :time_entry, :version]
   COLLECTION_OBSERVABLES = [:group_users, :issue_attachments, :project_attachments, :wiki_page_attachments]
-  SINGLE_OBSERVABLES = [:issue, :user, :group, :attachment, :project, :wiki_content, :time_entry, :version]
+  SINGLE_OBSERVABLES = [:issue, :issue_relation, :user, :group, :attachment, :project, :wiki_content, :time_entry, :version]
 
   has_and_belongs_to_many :projects
   acts_as_list

config/locales/en.yml

@@ -73,6 +73,9 @@ en:
   text_custom_workflow_issue_code_note: Scripts are executed in the context of Issue object like ordinary
     before_save and after_save callbacks. So use methods and properties of the issue directly (or through `self`).
     Instance variables (@variable) are also allowed and may be used if needed.
+  text_custom_workflow_issue_relation_code_note: Scripts are executed in the context of IssueRelation object like ordinary
+    before_save and after_save callbacks. So use methods and properties of the issue relation directly (or through `self`).
+    Instance variables (@variable) are also allowed and may be used if needed.
   text_custom_workflow_shared_code_note: This code will run before any other workflow and may contain shared code,
     e.g. functions and classes needed by other workflows
   text_custom_workflow_user_code_note: Scripts are executed in the context of User object when user object changes
@@ -107,6 +110,7 @@ en:
 
   custom_workflow_observable_shared: <shared code>
   custom_workflow_observable_issue: Issue
+  custom_workflow_observable_issue_relation: Issue Relation
   custom_workflow_observable_issue_attachments: Issue Attachments
   custom_workflow_observable_group: Group
   custom_workflow_observable_user: User

lib/redmine_custom_workflows.rb

@@ -30,10 +30,11 @@ require 'redmine_custom_workflows/errors/workflow_error'
 require 'redmine_custom_workflows/patches/attachment_patch'
 require 'redmine_custom_workflows/patches/group_patch'
 require 'redmine_custom_workflows/patches/issue_patch'
+require 'redmine_custom_workflows/patches/issue_relation_patch'
 require 'redmine_custom_workflows/patches/project_patch'
 require 'redmine_custom_workflows/patches/projects_helper_patch'
 require 'redmine_custom_workflows/patches/time_entry_patch'
 require 'redmine_custom_workflows/patches/user_patch'
 require 'redmine_custom_workflows/patches/version_patch'
 require 'redmine_custom_workflows/patches/wiki_content_patch'
-require 'redmine_custom_workflows/patches/wiki_page_patch'
+require 'redmine_custom_workflows/patches/wiki_page_patch'

lib/redmine_custom_workflows/patches/issue_relation_patch.rb

@@ -0,0 +1,78 @@
+# encoding: utf-8
+# frozen_string_literal: true
+#
+# Redmine plugin for Custom Workflows
+#
+# Copyright © 2015-19 Anton Argirov
+# Copyright © 2019-20 Karel Pičman <karel.picman@kontron.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+module RedmineCustomWorkflows
+  module Patches
+    module IssueRelationPatch
+
+      def self.included(base)
+        base.class_eval do
+          before_save :before_save_custom_workflows
+          after_save :after_save_custom_workflows
+          before_destroy :before_destroy_custom_workflows
+          after_destroy :after_destroy_custom_workflows
+
+          # override IssueRelation.to_s to rescue NoMethodError during CustomWorkflow.validate_syntax due to
+          # logging of temporarily instatiated IssueRelation with no related issues set
+          alias_method :old_to_s, :to_s
+    
+          def to_s(issue=nil)
+            block_given? ? old_to_s(issue, &Proc.new) : old_to_s(issue)
+          rescue NoMethodError => e
+            if issue_from.present? || issue_to.present?
+              raise e
+            end
+            self.class.to_s
+          end
+        end
+      end
+
+      def before_save_custom_workflows
+        @issue_relation = self
+        @saved_attributes = attributes.dup
+        CustomWorkflow.run_shared_code self
+        CustomWorkflow.run_custom_workflows :issue_relation, self, :before_save
+        throw :abort if errors.any?
+        errors.empty? && (@saved_attributes == attributes || valid?)
+      ensure
+        @saved_attributes = nil
+      end
+
+      def after_save_custom_workflows
+        CustomWorkflow.run_custom_workflows :issue_relation, self, :after_save
+      end
+
+      def before_destroy_custom_workflows
+        CustomWorkflow.run_custom_workflows :issue_relation, self, :before_destroy
+      end
+
+      def after_destroy_custom_workflows
+        CustomWorkflow.run_custom_workflows :issue_relation, self, :after_destroy
+      end
+
+    end
+  end
+end
+  
+# Apply patch
+RedmineExtensions::PatchManager.register_model_patch 'IssueRelation',
+  'RedmineCustomWorkflows::Patches::IssueRelationPatch'