Provide has_one id setters/getters, eliminating the need for explicitly defining them

Closes #2625

Author: mshibuya

lib/rails_admin/adapters/active_record/object_extension.rb

@@ -2,6 +2,24 @@ module RailsAdmin
   module Adapters
     module ActiveRecord
       module ObjectExtension
+        def self.extended(object)
+          object.class.reflect_on_all_associations.each do |association|
+            association = Association.new(association, object.class)
+            case association.type
+            when :has_one
+              object.instance_eval <<-RUBY, __FILE__, __LINE__ + 1
+                def #{association.name}_id
+                  self.#{association.name}&.id
+                end
+
+                def #{association.name}_id=(item_id)
+                  self.#{association.name} = #{association.klass}.find_by_id(item_id)
+                end
+              RUBY
+            end
+          end
+        end
+
         def assign_attributes(attributes)
           super if attributes
         end

lib/rails_admin/adapters/mongoid/object_extension.rb

@@ -18,6 +18,11 @@ def self.extended(object)
                   send(name)&.save
                 end
               end
+              object.instance_eval <<-RUBY, __FILE__, __LINE__ + 1
+                def #{name}_id=(item_id)
+                  self.#{name} = (#{association.klass}.find(item_id) rescue nil)
+                end
+              RUBY
             end
           end
         end

lib/rails_admin/config/fields/types/has_one_association.rb

@@ -17,10 +17,6 @@ class HasOneAssociation < RailsAdmin::Config::Fields::Association
             (o = value) && o.send(associated_model_config.object_label_method)
           end
 
-          def editable?
-            (nested_form || abstract_model.model.new.respond_to?("#{name}_id=")) && super
-          end
-
           def selected_id
             value.try :id
           end

spec/dummy_app/app/active_record/player.rb

@@ -17,12 +17,4 @@ class Player < ActiveRecord::Base
   scope :rails_admin_search, ->(query) { where(name: query.reverse) }
 
   def destroy_hook; end
-
-  def draft_id
-    draft.try :id
-  end
-
-  def draft_id=(id)
-    self.draft = Draft.find_by_id(id)
-  end
 end

spec/dummy_app/app/mongoid/player.rb

@@ -31,12 +31,4 @@ class Player
   scope :rails_admin_search, ->(query) { where(name: query.reverse) }
 
   def destroy_hook; end
-
-  def draft_id
-    draft.try :id
-  end
-
-  def draft_id=(id)
-    self.draft = Draft.where(_id: id).first
-  end
 end

spec/rails_admin/adapters/active_record/object_extension_spec.rb

@@ -9,4 +9,52 @@
       expect(object.assign_attributes(nil)).to be nil
     end
   end
+
+  describe 'has_one association' do
+    let(:draft) { FactoryBot.create(:draft) }
+    let(:player) { FactoryBot.build(:player).extend(RailsAdmin::Adapters::ActiveRecord::ObjectExtension) }
+    before do
+      class PlayerWithAutoSave < Player
+        has_one :draft, inverse_of: :player, foreign_key: :player_id, autosave: true
+      end
+    end
+
+    it 'provides id getter' do
+      player.draft = draft
+      expect(player.draft_id).to eq draft.id
+    end
+
+    context 'on create' do
+      before do
+        player.draft_id = draft.id
+        expect(player.draft).to receive(:save).once.and_call_original
+        player.save
+      end
+
+      it 'persists associated documents changes on save' do
+        expect(player.reload.draft).to eq draft
+      end
+    end
+
+    context 'on update' do
+      let(:player) { FactoryBot.create(:player).extend(RailsAdmin::Adapters::ActiveRecord::ObjectExtension) }
+      before do
+        player.draft_id = draft.id
+      end
+
+      it 'persists associated documents changes on assignment' do
+        expect(player.reload.draft).to eq draft
+      end
+    end
+
+    context 'with explicit id setter' do
+      let(:user) { ManagingUser.create(FactoryBot.attributes_for(:user)) }
+      let(:team) { ManagedTeam.create(FactoryBot.attributes_for(:team)) }
+
+      it 'works without issues' do
+        user.team_id = team.id
+        expect(user.reload.team).to eq team
+      end
+    end
+  end
 end

spec/rails_admin/adapters/mongoid/object_extension_spec.rb

@@ -110,5 +110,15 @@ class PlayerWithAutoSave < Player
         end
       end
     end
+
+    context 'with explicit id setter' do
+      let(:user) { ManagingUser.create(FactoryBot.attributes_for(:user)) }
+      let(:team) { ManagedTeam.create(FactoryBot.attributes_for(:team)) }
+
+      it 'works without issues' do
+        user.team_id = team.id
+        expect(user.reload.team).to eq team
+      end
+    end
   end
 end