Serialize groups as json for Dashboard::GroupsController

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/dashboard/groups_controller.rb

 class Dashboard::GroupsController < Dashboard::ApplicationController
   def index
-    @group_members = current_user.group_members.includes(source: :route).joins(:group)
-    @group_members = @group_members.merge(Group.search(params[:filter_groups])) if params[:filter_groups].present?
-    @group_members = @group_members.merge(Group.sort(@sort = params[:sort]))
-    @group_members = @group_members.page(params[:page])
+    @groups = if params[:parent_id]
+                parent = Group.find(params[:parent_id])
+
+                if parent.users_with_parents.find_by(id: current_user)
+                  Group.where(id: parent.children)
+                else
+                  Group.none
+                end
+              else
+                Group.joins(:group_members).merge(current_user.group_members)
+              end
+
+    @groups = @groups.search(params[:filter_groups]) if params[:filter_groups].present?
+    @groups = @groups.includes(:route)
+    @groups = @groups.sort(@sort = params[:sort])
+    @groups = @groups.page(params[:page])
     respond_to do |format|
       format.html
       format.json do
-        render json: {
-          html: view_to_html_string("dashboard/groups/_groups", locals: { group_members: @group_members })
-        }
+        render json: GroupSerializer
+          .new(current_user: @current_user)
+          .with_pagination(request, response)
+          .represent(@groups)
       end
     end
   end

app/serializers/group_entity.rb

+class GroupEntity < Grape::Entity
+  include RequestAwareEntity
+
+  expose :id, :name, :path, :description, :visibility
+  expose :avatar_url
+  expose :web_url
+  expose :full_name, :full_path
+  expose :parent_id
+  expose :created_at, :updated_at
+
+  expose :permissions do
+    expose :group_access do |group, options|
+      group.group_members.find_by(user_id: request.current_user)&.access_level
+    end
+  end
+end

app/serializers/group_serializer.rb

+class GroupSerializer < BaseSerializer
+  entity GroupEntity
+
+  def with_pagination(request, response)
+    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
+  end
+
+  def paginated?
+    @paginator.present?
+  end
+
+  def represent(resource, opts = {})
+    if paginated?
+      super(@paginator.paginate(resource), opts)
+    else
+      super(resource, opts)
+    end
+  end
+end

app/views/dashboard/groups/_groups.html.haml

 .js-groups-list-holder
   %ul.content-list
-    - @group_members.each do |group_member|
+    - @groups.each do |group|
+      - group_member = group.group_members.find_by(user_id: current_user)
       = render 'shared/groups/group', group: group_member.group, group_member: group_member
-  = paginate @group_members, theme: 'gitlab'
+  = paginate @groups, theme: 'gitlab'

app/views/dashboard/groups/index.html.haml

@@ -2,7 +2,7 @@
 - header_title  "Groups", dashboard_groups_path
 = render 'dashboard/groups_head'
-- if @group_members.empty?
+- if @groups.empty?
   = render 'empty_state'
 - else
   = render 'groups'