作品列表为空时缺评列表报错

app/controllers/student_work_controller.rb

@@ -245,15 +245,19 @@ class StudentWorkController < ApplicationController
   def student_work_absence_penalty
     render_403 unless User.current.allowed_to?(:as_teacher,@course)
     order = params[:order] || "desc"
-    work_ids = "(" + @homework.student_works.map(&:id).join(",") + ")"
+    if @homework.student_works.empty?
-    @stundet_works = StudentWork.find_by_sql("SELECT *,(all_count - has_count) AS absence FROM(
+      @stundet_works = []
+    else
+      work_ids = "(" + @homework.student_works.map(&:id).join(",") + ")"
+      @stundet_works = StudentWork.find_by_sql("SELECT *,(all_count - has_count) AS absence FROM(
       SELECT * ,
         (SELECT COUNT(*) FROM `student_works_evaluation_distributions` WHERE user_id = student_works.user_id AND student_work_id IN #{work_ids}) AS all_count,
         (SELECT COUNT(*) FROM `student_works_scores` WHERE user_id = student_works.user_id AND student_work_id IN #{work_ids}) AS has_count
       FROM `student_works`
       WHERE homework_common_id = #{@homework.id}
-    ) AS table_1
+      ) AS table_1
-    ORDER BY absence #{order}")
+      ORDER BY absence #{order}")
+    end
     @order = order == "desc" ? "asc" : "desc"
     respond_to do |format|
       format.html