修改作业数据迁移

db/migrate/20140604071624_rename_project_id_to_homework_for_courses.rb

@@ -4,10 +4,9 @@ class RenameProjectIdToHomeworkForCourses < ActiveRecord::Migration
 
     # 作业数据迁移
     HomeworkForCourse.all.each do |work|
-      project = Project.find_by_id(work.project_id)
+      project = Project.find_by_id(work.course_id)
       if project && project.project_type == 1
         work.course_id = project.course_extra.id
-        work.project_id = -1
         work.save
       end
     end