AssetTagHelper::image_path 外部视图

发布于 2024-09-25 02:02:42 字数 420 浏览 4 评论 0原文

据推测，ActionController::Base.helpers 充当访问视图外部助手的代理。然而，那里定义的许多方法都依赖于控制器变量，我无法成功调用：

ActionController::Base.helpers.image_path("my_image.png")
>> TypeError Exception: can't convert nil into String

深入挖掘源代码，我看到 compute_asset_host 方法正在尝试访问 config.asset_host 但config 为nil。

如何从外部视图成功调用 image_path？

原文

Supposedly, ActionController::Base.helpers acts like a proxy for accessing helpers outside views. However many of the methods defined there rely on controller variables and I'm unable to succesfully call:

ActionController::Base.helpers.image_path("my_image.png")
>> TypeError Exception: can't convert nil into String

Digging at the source I see compute_asset_host method is trying to access config.asset_host but config is nil.

How can I successfully call image_path from outside views?

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看春风乍起 2024-10-02 02:02:42

使用 view_context 访问视图中可用的辅助方法。

您可以从控制器中像这样调用image_path。

view_context.image_path "my_image.png"

Use view_context to access those helper methods that are available in the view.

You can call image_path like this from the controller.

view_context.image_path "my_image.png"

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那支青花 2024-10-02 02:02:42

对于 Rails 3，请在此处查看更清晰的解决方案如何我在 Rails 3 控制器中使用 image_path

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一枫情书 2024-10-02 02:02:42

Mason Jones 发布的此解决方案适合我。

在您的应用程序控制器中：

def self.tag_helper
  TagHelper.instance
end

class TagHelper
  include Singleton
  include ActionView::Helpers::TagHelper
  include ActionView::Helpers::AssetTagHelper
end

然后您可以执行以下操作，或执行您需要的任何其他操作。

active_scaffold :mything do |config|
  config.columns = [:name, :number, :active, :description]
  config.update.link.label = tag_helper.image_tag('document_edit.png', :width => "30")
  config.delete.link.label = tag_helper.image_tag('document_delete.png', :width => "30")
  config.show.link.label = tag_helper.image_tag('document.png', :width => "30")
  list.sorting = {:name => 'ASC'}
end

您正在 ApplicationController 中创建 TagHelper 的 Singelton 实例。无论您需要什么，这都会为您提供帮助。他在帖子中对此进行了解释。

另外，我用它来扩展我的模型（创建一个更灵活的 image_tag 帮助器，如果不存在图像，它会返回默认图像 - 例如 person.small_image 是 person 模型的实例变量，它使用 tag_helper）。为此，我将相同的代码放入扩展 ActiveRecord::Base 的 Monkey Patch 初始值设定项中。然后，我从模型中调用 ActiveRecord::Base.tag_helper 。这有点混乱，但我是 Rails 新手。可能有一种更清洁的方法。

希望有帮助。

This solution, posted by Mason Jones, works for me.

In your application controller:

def self.tag_helper
  TagHelper.instance
end

class TagHelper
  include Singleton
  include ActionView::Helpers::TagHelper
  include ActionView::Helpers::AssetTagHelper
end

Then you can do the following kind of thing, or whatever else you need.

active_scaffold :mything do |config|
  config.columns = [:name, :number, :active, :description]
  config.update.link.label = tag_helper.image_tag('document_edit.png', :width => "30")
  config.delete.link.label = tag_helper.image_tag('document_delete.png', :width => "30")
  config.show.link.label = tag_helper.image_tag('document.png', :width => "30")
  list.sorting = {:name => 'ASC'}
end

You're creating a Singelton instance of TagHelper in your ApplicationController. This gives you the helpers wherever you need them. He explains it in his post.

Also, I use this to extend my models (to create a more flexible image_tag helper that returns a default image if there's no image present -- e.g. person.small_image is an instance variable of the person model, which uses tag_helper). To do that I've put the same code in a Monkey Patch initializer that extends ActiveRecord::Base. I then call ActiveRecord::Base.tag_helper from within my models. This is a bit messy, but I'm new to rails. There's probably a cleaner way.

Hope that helps.

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