adapt list custom field filter to alterations caused by multi select

app/models/queries/work_packages/filter/custom_field_filter.rb

@@ -111,7 +111,7 @@ class Queries::WorkPackages::Filter::CustomFieldFilter <
   end
 
   def ar_object_filter?
-    %w{user version}.include? custom_field.field_format
+    %w{user version list}.include? custom_field.field_format
   end
 
   def value_objects
@@ -120,6 +120,8 @@ class Queries::WorkPackages::Filter::CustomFieldFilter <
       User.find(values)
     when 'version'
       Version.find(values)
+    when 'list'
+      value_objects_for_list
     else
       super
     end
@@ -153,4 +155,28 @@ class Queries::WorkPackages::Filter::CustomFieldFilter <
     !self.class.custom_fields(context)
          .map(&:id).include? custom_field.id
   end
+
+  def value_objects_for_list
+    objects = allowed_values.select do |value|
+      values.include? value.last.to_s
+    end
+
+    objects.map do |value|
+      Queries::StringObject.new(value.last, value.first)
+    end
+  end
+end
+
+#
+# This object is only used to transport the values tothe query filter instance
+# representer which expects a class and deduces the path from the classes' name.
+#
+class Queries::StringObject
+  attr_accessor :id,
+                :name
+
+  def initialize(id, name)
+    self.id = [name, id]
+    self.name = name
+  end
 end

lib/api/v3/queries/filters/query_filter_instance_representer.rb

@@ -55,7 +55,7 @@ module API
 
             represented.value_objects.map do |value_object|
               {
-                href: api_v3_paths.send(value_object.class.name.underscore, value_object.id),
+                href: api_v3_paths.send(value_object.class.name.demodulize.underscore, value_object.id),
                 title: value_object.name
               }
             end

lib/api/v3/queries/schemas/string_object_filter_dependency_representer.rb

@@ -41,7 +41,7 @@ module API
                                          required: true,
                                          visibility: false,
                                          values_callback: ->(*) {
-                                           represented.allowed_values.map(&:last)
+                                           represented.allowed_values
                                          },
                                          value_representer: StringObjects::StringObjectRepresenter,
                                          link_factory: ->(value) {

spec/lib/api/v3/queries/schemas/string_object_filter_dependency_representer_spec.rb

@@ -55,7 +55,7 @@ describe ::API::V3::Queries::Schemas::StringObjectFilterDependencyRepresenter do
         let(:type) { '[]StringObject' }
         let(:hrefs) do
           filter.allowed_values.each_with_object([]) do |value, array|
-            array << api_v3_paths.string_object(value.last)
+            array << api_v3_paths.string_object(value)
           end
         end
 

spec/models/queries/work_packages/filter/custom_field_filter_spec.rb

@@ -398,7 +398,36 @@ describe Queries::WorkPackages::Filter::CustomFieldFilter, type: :model do
     context 'list cf' do
       let(:custom_field) { list_wp_custom_field }
 
-      it_behaves_like 'non ar filter'
+      describe '#ar_object_filter?' do
+        it 'is true' do
+          expect(instance)
+            .to be_ar_object_filter
+        end
+      end
+
+      describe '#value_objects' do
+        before do
+          instance.values = [custom_field.custom_options.last.id,
+                             custom_field.custom_options.first.id]
+        end
+
+        it 'returns an array with custom classes' do
+          expect(instance.value_objects.length)
+            .to eql(2)
+
+          expect(instance.value_objects[0].id)
+            .to match_array([custom_field.custom_options.first.value,
+                             custom_field.custom_options.first.id])
+          expect(instance.value_objects[0].name)
+            .to eql(custom_field.custom_options.first.value)
+
+          expect(instance.value_objects[1].id)
+            .to match_array([custom_field.custom_options.last.value,
+                             custom_field.custom_options.last.id])
+          expect(instance.value_objects[1].name)
+            .to eql(custom_field.custom_options.last.value)
+        end
+      end
     end
 
     context 'bool cf' do