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Rails：葡萄API - NameError：未初始化常量API

ruby-on-railsruby
3
我正在学习如何使用Rails。我按照这个网站上的教程进行操作： http://funonrails.com/2014/03/building-restful-api-using-grape-in-rails/ 我将我的文件放在了app文件夹而不是lib文件夹中，并按照教程中所说编辑了application.rb文件。其余代码与教程中相同。
我完成了自定义错误格式化器，但如果我启动Rails服务器以测试所有内容，我会收到以下错误：
                Exiting
E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/routes.rb:3:in `block in <top (required)>': uninitialized constant API (NameError)
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/routing/route_set.rb:337:in `instance_exec'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/routing/route_set.rb:337:in `eval_block'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/actionpack-4.1.8/lib/action_dispatch/routing/route_set.rb:315:in `draw'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/routes.rb:1:in `<top (required)>'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:40:in `each'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:40:in `load_paths'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:16:in `reload!'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:26:in `block in updater'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.8/lib/active_support/file_update_checker.rb:75:in `call'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.8/lib/active_support/file_update_checker.rb:75:in `execute'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/routes_reloader.rb:27:in `updater'
    from C:in `execute_if_updated'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application/finisher.rb:71:in `block in <module:Finisher>'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/initializable.rb:30:in `instance_exec'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/initializable.rb:30:in `run'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/initializable.rb:55:in `block in run_initializers'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:226:in `block in tsort_each'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:427:in `each_strongly_connected_component_from'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:347:in `block in each_strongly_connected_component'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `call'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each_strongly_connected_component'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:224:in `tsort_each'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/2.1.0/tsort.rb:205:in `tsort_each'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/initializable.rb:54:in `run_initializers'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/application.rb:300:in `initialize!'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/environment.rb:5:in `<top (required)>'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config.ru:3:in `require'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config.ru:3:in `block in <main>'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config.ru:in `new'
    from E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config.ru:in `<main>'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `eval'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `new_from_string'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:40:in `parse_file'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:277:in `build_app_and_options_from_config'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:199:in `app'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/server.rb:50:in `app'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:314:in `wrapped_app'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/server.rb:130:in `log_to_stdout'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/server.rb:67:in `start'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:81:in `block in server'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:76:in `tap'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:76:in `server'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
    from C:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.8/lib/rails/commands.rb:17:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

如果我没有启动服务器但调用rake routes，我会收到以下错误信息：
rake aborted!
NameError: uninitialized constant API
E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/routes.rb:3:in `block in <top (required)>'
E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/routes.rb:1:in `<top (required)>'
C:in `execute_if_updated'
E:/Users/Robert/Documents/Rubymine Projects/WarframeApi/config/environment.rb:5:in `<top (required)>'
Tasks: TOP => routes => environment
(See full trace by running task with --trace)

建议？
下面是编辑内容
应用程序.rb
require File.expand_path('../boot', __FILE__)

require 'rails/all'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module WarframeApi
  class Application < Rails::Application

    # Api load config
    config.paths.add "app/api", glob: "**/*.rb"
    config.autoload_paths += Dir["#{Rails.root}/app/api/*"]
  end
end

Routes.rb

Rails.application.routes.draw do
    mount API::Root => '/'
end

API文件位于./app/api目录中（如教程中建议的备选位置）。以下是完整的文件结构：

  • app
    • api
      • root.rb
      • v1
        • authors.rb
        • posts.rb
        • root.rb
请将application.rb添加到此处。你把API模块放在哪里了？ - Sharvy Ahmed
请添加您的routes.rb文件，包括与您的“api”路径相关的部分。 - MarsAtomic
已经添加了，但与教程中的相同。正如我之前所写的：代码与教程中的完全相同。 - Ruhrpottpatriot
3个回答
5

将您的root.rb更改为以下内容：

class Root < Grape::API
  prefix 'api'
  mount V1::Root
  # mount V2::Root (next version)
end

或者，将您的目录结构更改为以下方式：
app > api > api > root.rb

Rails正在寻找api文件夹，因为您正在使用模块API。但是，由于您已经在application.rb中自动加载了api文件夹，所以如果您保持root.rb不变，就需要另一个api文件夹。
请查看更新后的问题以获取更多细节。虽然我按照您的建议进行了更改，但仍然无法正常工作。 - Ruhrpottpatriot
我的回答已更新，请查看。 - Sharvy Ahmed
@Ruhrpottpatriot，你试过了吗？ - Sharvy Ahmed
更改目录结构确实有效。但是那个结构不是我喜欢的。所以小问题：你指的是哪个root.rb？是在api中的那个，还是在api/v1文件夹中的那个？因为更改api文件夹中的那个并没有起作用。 - Ruhrpottpatriot
2
我通过更改config/routes.rb中的内容来解决这个问题：
将
mount V1::Root => "/"
改为
mount Root => "/api"
1
你只需要创建另一个目录结构

  • app

    • api

      • api

        • v1

          • authors.rb
          • posts.rb
          • root.rb

        • root.rb

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