热门项目排序添加空值判断，默认按活跃度排序

app/controllers/welcome_controller.rb

@@ -32,25 +32,29 @@ class WelcomeController < ApplicationController
     @projects_all = Project.active.visible.
         joins("LEFT JOIN #{ProjectStatus.table_name} ON #{Project.table_name}.id = #{ProjectStatus.table_name}.project_id").
         where("#{Project.table_name}.project_type = ? and #{Project.table_name}.id in (?)", Project::ProjectType_project,@hot_projects_ids)
-
-    case @first_page.sort_type
-      when 0
-        @projects =  @projects_all.order("created_on desc")
-      when 1
-        @projects = @projects_all.order("grade desc")
-      when 2
-        @projects = @projects_all.order("watchers_count desc")
-
-      #gcm
-      #when '3'
+    if @first_page.nil? ||  @first_page.sort_type.nil?
+      @projects = @projects_all.order("grade desc")
+    else
+      case @first_page.sort_type
+        when 0
+          @projects =  @projects_all.order("created_on desc")
+        when 1
+          @projects = @projects_all.order("grade desc")
+        when 2
+          @projects = @projects_all.order("watchers_count desc")
+
+        #gcm
+        #when '3'
         #@projects=desc_sort_course_by_avtivity(@project_activity_count_array,@project_all_array)
-      #  @projects=handle_project @projects_all,@project_activity_count
-      #  @s_type = 3
-      #  @projects =  @projects[@project_pages.offset, @project_pages.per_page]
+        #  @projects=handle_project @projects_all,@project_activity_count
+        #  @s_type = 3
+        #  @projects =  @projects[@project_pages.offset, @project_pages.per_page]
 
-      else
-        @projects = @projects_all.order("grade desc")
+        else
+          @projects = @projects_all.order("grade desc")
+      end
     end
+
   end
 
   def robots