Allow filtering children for a group

When fetching children for a group with a filter, we will search all
nested groups for results and render them in an expanded tree

app/controllers/groups_controller.rb

@@ -74,11 +74,11 @@ class GroupsController < Groups::ApplicationController
 
     respond_to do |format|
       format.json do
-        render json: GroupChildSerializer
-                 .new(current_user: current_user)
-                 .with_pagination(request, response)
-                 .hierarchy_base(parent, open_hierarchy: filter[:filter].present)
-                 .represent(@children)
+        serializer = GroupChildSerializer
+                       .new(current_user: current_user)
+                       .with_pagination(request, response)
+        serializer.expand_hierarchy(parent) if params[:filter].present?
+        render json: serializer.represent(@children)
       end
     end
   end

app/serializers/group_child_serializer.rb

@@ -18,11 +18,14 @@ class GroupChildSerializer < BaseSerializer
     end
   end
 
+  protected
+
   def represent_hierarchies(children, opts)
     if children.is_a?(GroupHierarchy)
-      represent_hierarchy(children.hierarchy(hierarchy_root), opts)
+      represent_hierarchy(children.hierarchy(hierarchy_root), opts).first
     else
-      children.map { |child| represent_hierarchy(child.hierarchy(hierarchy_root), opts) }
+      hierarchies = Array.wrap(GroupHierarchy.merge_hierarchies(children, hierarchy_root))
+      hierarchies.map { |hierarchy| represent_hierarchy(hierarchy, opts) }.flatten
     end
   end
 
@@ -30,9 +33,10 @@ class GroupChildSerializer < BaseSerializer
     serializer = self.class.new(parameters)
 
     result = if hierarchy.is_a?(Hash)
-               parent = hierarchy.keys.first
-               serializer.represent(parent, opts)
-                 .merge(children: [serializer.represent_hierarchy(hierarchy[parent], opts)])
+               hierarchy.map do |parent, children|
+                 serializer.represent(parent, opts)
+                   .merge(children: Array.wrap(serializer.represent_hierarchy(children, opts)))
+               end
              else
                serializer.represent(hierarchy, opts)
              end

spec/controllers/groups_controller_spec.rb

@@ -224,6 +224,36 @@ describe GroupsController do
           expect(assigns(:children)).to contain_exactly(public_subgroup, public_project)
         end
       end
+
+      context 'filtering children' do
+        def get_filtered_list
+          get :children, id: group.to_param, filter: 'filter', format: :json
+        end
+
+        it 'expands the tree for matching projects' do
+          project = create(:project, :public, namespace: public_subgroup, name: 'filterme')
+
+          get_filtered_list
+
+          group_json = json_response.first
+          project_json = group_json['children'].first
+
+          expect(group_json['id']).to eq(public_subgroup.id)
+          expect(project_json['id']).to eq(project.id)
+        end
+
+        it 'expands the tree for matching subgroups' do
+          matched_group = create(:group, :public, parent: public_subgroup, name: 'filterme')
+
+          get_filtered_list
+
+          group_json = json_response.first
+          matched_group_json = group_json['children'].first
+
+          expect(group_json['id']).to eq(public_subgroup.id)
+          expect(matched_group_json['id']).to eq(matched_group.id)
+        end
+      end
     end
   end
 

spec/serializers/group_child_serializer_spec.rb

@@ -16,7 +16,7 @@ describe GroupChildSerializer do
       end
     end
 
-    context 'with a hierarchy' do
+    context 'with a hierarchy', :nested_groups do
       let(:parent) { create(:group) }
 
       subject(:serializer) do
@@ -35,8 +35,51 @@ describe GroupChildSerializer do
         expect(subsub_group_json[:id]).to eq(subsub_group.id)
       end
 
-      it 'can expand multiple trees' do
+      it 'can render a nested tree' do
+        subgroup1 = create(:group, parent: parent)
+        subsub_group1 = create(:group, parent: subgroup1)
+        subgroup2 = create(:group, parent: parent)
+        subsub_group2 = create(:group, parent: subgroup2)
 
+        json = serializer.represent([subsub_group1, subsub_group2])
+        subgroup1_json = json.first
+        subsub_group1_json = subgroup1_json[:children].first
+
+        expect(json.size).to eq(2)
+        expect(subgroup1_json[:id]).to eq(subgroup1.id)
+        expect(subsub_group1_json[:id]).to eq(subsub_group1.id)
+      end
+    end
+
+    context 'for projects' do
+      it 'can render a single project' do
+        expect(serializer.represent(build(:project))).to be_kind_of(Hash)
+      end
+
+      it 'can render a collection of projects' do
+        expect(serializer.represent(build_list(:project, 2))).to be_kind_of(Array)
+      end
+
+      context 'with a hierarchy', :nested_groups do
+        let(:parent) { create(:group) }
+
+        subject(:serializer) do
+          described_class.new(current_user: user).expand_hierarchy(parent)
+        end
+
+        it 'can render a nested tree' do
+          subgroup1 = create(:group, parent: parent)
+          project1 = create(:project, namespace: subgroup1)
+          subgroup2 = create(:group, parent: parent)
+          project2 = create(:project, namespace: subgroup2)
+
+          json = serializer.represent([project1, project2])
+          project1_json, project2_json = json.map { |group_json| group_json[:children].first }
+
+          expect(json.size).to eq(2)
+          expect(project1_json[:id]).to eq(project1.id)
+          expect(project2_json[:id]).to eq(project2.id)
+        end
       end
     end
   end