update former type column on changes to relation_type

app/models/relation.rb

@@ -177,6 +177,14 @@ class Relation < ActiveRecord::Base
     changed.include?('relation_type')
   end
 
+  def relation_type_was
+    if changes['relation_type']
+      changes['relation_type'].first
+    else
+      relation_type
+    end
+  end
+
   def relation_type
     if @relation_type.present?
       @relation_type
@@ -247,6 +255,8 @@ class Relation < ActiveRecord::Base
     end
   end
 
+  private
+
   def shared_hierarchy?
     to_from = hierarchy_but_not_self(to: to, from: from)
     from_to = hierarchy_but_not_self(to: from, from: to)
@@ -256,8 +266,6 @@ class Relation < ActiveRecord::Base
       .any?
   end
 
-  private
-
   def validate_sanity_of_relation
     return unless from && to
 
@@ -268,11 +276,15 @@ class Relation < ActiveRecord::Base
   end
 
   def set_type_column
-    return unless relation_type
+    if relation_type_changed? && relation_type_was
+      was_column = self.class.relation_column(relation_type_was)
+      send("#{was_column}=", 0)
+    end
 
-    column = self.class.relation_column(relation_type)
+    return unless relation_type
+    new_column = self.class.relation_column(relation_type)
 
-    send("#{column}=", 1)
+    send("#{new_column}=", 1)
   end
 
   # Reverses the relation if needed so that it gets stored in the proper way

spec/features/work_packages/details/details_relations_spec.rb

@@ -147,7 +147,7 @@ describe 'Work package relations tab', js: true, selenium: true do
       expect(page).to have_selector('.relation-row--type', text: 'Related To')
 
       updated_relation = Relation.find(relation_1.id)
-      expect(updated_relation.relation_type).to eq(:blocks) # ! Reports mixed
+      expect(updated_relation.relation_type).to eq('blocks')
     end
   end
 

spec/models/relation_spec.rb

@@ -120,19 +120,20 @@ describe Relation, type: :model do
   end
 
   describe '#relation_type=' do
-    let(:column_name) { :relates }
+    let(:column_name) { 'relates' }
     let(:type) { :relates }
     let(:relation) do
-      FactoryGirl.build_stubbed(:relation,
-                                relation_type: :relates,
-                                relates: 1)
+      FactoryGirl.build(:relation,
+                        relation_type: 'relates')
     end
 
     it 'updates the column value' do
+      relation.save!
       expect(relation.relates).to eq 1
 
-      relation.relation_type = :duplicates
-      expect(relation.relation_type).to eq(:duplicates)
+      relation.relation_type = 'duplicates'
+      relation.save!
+      expect(relation.relation_type).to eq('duplicates')
 
       expect(relation.relates).to eq 0
       expect(relation.duplicates).to eq 1