Rails应用回滚提交后出现ActionView语法错误，求排查与CoffeeScript修正

错误日志 #

Processing by MainController#index as HTML
  Rendering layout layouts/lmt.html.erb
  Rendering main/index.html.erb within layouts/lmt
  Event Load (1.0ms)  SELECT "events".* FROM "events"
  ↳ app/views/main/index.html.erb:14
  Rendered main/index.html.erb within layouts/lmt (Duration: 357.4ms | Allocations: 238507)
  Rendered layout layouts/lmt.html.erb (Duration: 357.6ms | Allocations: 238584)
Completed 500 Internal Server Error in 358ms (ActiveRecord: 1.0ms | Allocations: 239010)
 
ActionView::Template::Error (SyntaxError: [stdin]:15:1: unexpected indentation):
  
(execjs):7539:8
(execjs):7557:14
(execjs):1:32

问题根源 #

报错指向execjs但并非该文件本身有问题，而是你的application.coffee存在缩进错误——CoffeeScript依赖严格的缩进划分代码块，错误的缩进会导致编译失败。

错误的CoffeeScript代码 #

# app/assets/javascript/packs/application.coffee

setup = ->

  $(document).foundation();

$ ->

  console.log "Loading page...!  " + Date.now()%10000

  setup()

  document.addEventListener "turbolinks:load", () ->

  console.log "turbolinks:load "  + Date.now()%10000

    setup()

修复后的代码 #

# app/assets/javascript/packs/application.coffee

setup = ->
  $(document).foundation()

$ ->
  console.log "Loading page...!  " + Date.now()%10000
  setup()

  document.addEventListener "turbolinks:load", ->
    console.log "turbolinks:load "  + Date.now()%10000
    setup()

修复说明 #

1. 统一缩进层级：每个函数（->）后的代码必须缩进一层，确保代码块归属正确，这是CoffeeScript的核心语法规则
2. 移除冗余分号：CoffeeScript会自动处理语句结尾，无需手动添加分号
3. 修正回调代码块：turbolinks:load的回调函数内部，console.log和setup()都需缩进至回调函数层级，避免出现意外缩进的语法错误

内容的提问来源于stack exchange，提问作者John Cowan