迁移错误和回滚尝试

Question

目前正在制作一个 reddit 类型的网站，并且发现（无论出于何种原因）我创建 cmets 的迁移在处理其他“移动部件”后不再存在。我开始生成一个新的评论迁移，并看到了一堵漂亮的墙“StandardError：发生错误，这个和所有后来的迁移都取消了：[...]”我研究了回滚/删除迁移以解决我的问题，但似乎无处可去。下面是我在害怕彻底毁掉它之前努力修复我的应用程序的结果。

Kristoffers-MBP:bloccit Juice$ rake db:migrate:status

database: /Users/Juice/code/bloccit/db/development.sqlite3

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20150315080918  Create advertisements
   up     20150321042053  Devise create users
   up     20150323040831  Add role to users
   up     20150328164720  Create topics
   up     20150328170242  Add topic to posts
   up     20150405212530  Add avatar to users
   up     20150406044601  ********** NO FILE **********
  down    20150412173406  Create comments

Kristoffers-MBP:bloccit Juice$ rake db:rollback
Kristoffers-MBP:bloccit Juice$ rake db:migrate:status

database: /Users/Juice/code/bloccit/db/development.sqlite3

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20150315080918  Create advertisements
   up     20150321042053  Devise create users
   up     20150323040831  Add role to users
   up     20150328164720  Create topics
   up     20150328170242  Add topic to posts
   up     20150405212530  Add avatar to users
   up     20150406044601  ********** NO FILE **********
  down    20150412173406  Create comments

Kristoffers-MBP:bloccit Juice$ rake db:rollback
Kristoffers-MBP:bloccit Juice$ rake db:migrate:status

database: /Users/Juice/code/bloccit/db/development.sqlite3

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20150315080918  Create advertisements
   up     20150321042053  Devise create users
   up     20150323040831  Add role to users
   up     20150328164720  Create topics
   up     20150328170242  Add topic to posts
   up     20150405212530  Add avatar to users
   up     20150406044601  ********** NO FILE **********
  down    20150412173406  Create comments

Kristoffers-MBP:bloccit Juice$ rake db:rollback
Kristoffers-MBP:bloccit Juice$ rake db:migrate:status

database: /Users/Juice/code/bloccit/db/development.sqlite3

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20150315080918  Create advertisements
   up     20150321042053  Devise create users
   up     20150323040831  Add role to users
   up     20150328164720  Create topics
   up     20150328170242  Add topic to posts
   up     20150405212530  Add avatar to users
   up     20150406044601  ********** NO FILE **********
  down    20150412173406  Create comments

Kristoffers-MBP:bloccit Juice$ rake db:migrate:down VERSION=20150412173406
Kristoffers-MBP:bloccit Juice$ rake db:migrate:status

database: /Users/Juice/code/bloccit/db/development.sqlite3

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20150315080918  Create advertisements
   up     20150321042053  Devise create users
   up     20150323040831  Add role to users
   up     20150328164720  Create topics
   up     20150328170242  Add topic to posts
   up     20150405212530  Add avatar to users
   up     20150406044601  ********** NO FILE **********
  down    20150412173406  Create comments

Answer 1

尝试： 耙分贝：下降

耙数据库：创建

rake db:迁移

注意：所有保存在数据库中的数据都会丢失。