图像在 Rails 3.1 on Production (Heroku) 中显示为空白

Question

我最近将我的 Rails 更新到 3.1。

这是我添加的部分：

<%= asset_path('logo_symbol.png') %>

这会呈现/assets/logo_symbol.png，它在开发环境中工作得非常好。但是，当我在 heroku 上将代码推送到生产环境时，它会显示一个损坏的图像，网址为：assets/logo_symbol-135ddc8db2c9b59f032bed7db520137a.png。我猜这个新名称是出于一些优化的原因。

有趣的是，当我在生产环境中访问 assets/logo_symbol-135ddc8db2c9b59f032bed7db520137a.png url 时，我看到一个空白页面，但是当我将该 url 更改为任何随机的东西时，比如向其中添加数字，它会显示一个找不到页面.很明显，它在那个 url 上找到了一些东西。当我直接在 production/heroku 上转到 /assets/logo_symbol.png 时，它也会显示一个空白页面。

如果这有帮助，当我推送代码时 heroku 没有成功预编译，heroku 的文档说目前没有解决该问题的方法。

我们将不胜感激。

我的猜测是它与一些与环境相关的配置有关。我正在附加我的 application.rb、development.rb 和 production.rb 文件的内容

这是我的 production.rb 文件的内容

 # Settings specified here will take precedence over those in config/application.rb

  # In the development environment your application's code is reloaded on
  # every request.  This slows down response time but is perfect for development
  # since you don't have to restart the webserver when you make code changes.
  config.cache_classes = false

  # Log error messages when you accidentally call methods on nil.
  config.whiny_nils = true

  # Show full error reports and disable caching
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  # Don't care if the mailer can't send

  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  config.action_mailer.delivery_method = :smtp

  # Print deprecation notices to the Rails logger
  config.active_support.deprecation = :log

  # Only use best-standards-support built into browsers
  config.action_dispatch.best_standards_support = :builtin

  # Do not compress assets
  config.assets.compress = false

  # Expands the lines which load the assets
  config.assets.debug = true
end

module ActiveAdmin
  class Reloader
    def attach!
    end
  end
end

这是我的 development.rb 文件的内容

 # Settings specified here will take precedence over those in config/application.rb

  # In the development environment your application's code is reloaded on
  # every request.  This slows down response time but is perfect for development
  # since you don't have to restart the webserver when you make code changes.
  config.cache_classes = false

  # Log error messages when you accidentally call methods on nil.
  config.whiny_nils = true

  # Show full error reports and disable caching
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  # Don't care if the mailer can't send

  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  #config.action_mailer.default_url_options = { :host => 'localhost:3000' }
  config.action_mailer.delivery_method = :smtp

  # Print deprecation notices to the Rails logger
  config.active_support.deprecation = :log

  # Only use best-standards-support built into browsers
  config.action_dispatch.best_standards_support = :builtin

  # Do not compress assets
  config.assets.compress = false

  # Expands the lines which load the assets
  config.assets.debug = true
end

module ActiveAdmin
  class Reloader
    def attach!
    end
  end
end

这是我的 production.rb 文件的内容

  # Settings specified here will take precedence over those in config/application.rb

  # The production environment is meant for finished, "live" apps.
  # Code is not reloaded between requests
  config.cache_classes = true

  # Full error reports are disabled and caching is turned on
  config.consider_all_requests_local       = false
  config.action_controller.perform_caching = true

  # Specifies the header that your server uses for sending files
  config.action_dispatch.x_sendfile_header = "X-Sendfile"

  # For nginx:
  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect'

  # If you have no front-end server that supports something like X-Sendfile,
  # just comment this out and Rails will serve the files

  # See everything in the log (default is :info)
  # config.log_level = :debug

  # Use a different logger for distributed setups
  # config.logger = SyslogLogger.new

  # Use a different cache store in production
  # config.cache_store = :mem_cache_store

  # Disable Rails's static asset server
  # In production, Apache or nginx will already do this
  config.serve_static_assets = false

  # Enable serving of images, stylesheets, and javascripts from an asset server
  # config.action_controller.asset_host = "http://assets.example.com"

  # Disable delivery errors, bad email addresses will be ignored
  # config.action_mailer.raise_delivery_errors = false

  #config.action_mailer.default_url_options = { :host => 'ha1.heroku.com' }
  config.action_mailer.delivery_method = :smtp

  # Enable threaded mode
  # config.threadsafe!

  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
  # the I18n.default_locale when a translation can not be found)
  config.i18n.fallbacks = true

  # Send deprecation notices to registered listeners
  config.active_support.deprecation = :notify

  # Compress JavaScripts and CSS
  #config.assets.compress = true

  # Don't fallback to assets pipeline if a precompiled asset is missed
  config.assets.compile = false

  # Generate digests for assets URLs
  config.assets.digest = true

  # Defaults to Rails.root.join("public/assets")
  # config.assets.manifest = YOUR_PATH

  config.assets.js_compressor  = :uglifier
  config.assets.css_compressor = :scss

我已将我的配置文件与 3.1 的 rails 文档进行了比较，似乎我拥有所需的所有默认值。但是我仍然看不到任何图像。任何帮助将不胜感激

Answer 1

从 production.rb 中删除这一行：

config.action_dispatch.x_sendfile_header = "X-Sendfile"

您还应该将配置文件中的设置与section 9 of the pipeline guides 中的设置对齐。

Sendfile 标头包含上游网络服务器在哪里可以找到文件（在文件系统上）以提供服务的信息。这消除了后端（Rails/Sprockets）的负载。当 sendfile 位于 HTTP 响应上时，它不包含正文（长度为零），这就是您什么都看不到的原因。

在 heroku 上，nginx 服务器无法访问应用程序文件系统，因此这不起作用。

请参阅 Heroku 开发网站上的 this note 重新发送文件。

如果您使用的是 heroku，this document 列出了有效使用管道的最佳选项。

Answer 2

你需要做两件事来解决它。 首先，在 production.rb 文件中将这两行从 false 更改为 true。

      config.assets.compile = true
      config.assets.digest = true

其次，如果你的图片有这样的语法

    background: url("imgo.jpg") 

改成

     background: image-url("image.jpg")

我希望它能完成你的工作。