[英]Ruby on Rails cannot load concern module
I have initialized a module in the folder "concerns" located in: appname/app/models/concerns 我已经在以下文件夹中的“关注点”中初始化了一个模块: appname / app / models / concerns
called current_cart.rb 叫做current_cart.rb
appname/app/models/concerns/current_cart.rb appname / app / models / concerns / current_cart.rb
module CurrentCart
extend ActiveSupport::Concern
private
def set_cart
@cart = Cart.find(session[:cart_id])
rescue ActiveRecord::RecordNotFound
@cart = Cart.create
session[:cart_id] = @cart.id
end
end
i'm including this in my controller line_item_controllers: 我将其包含在我的控制器line_item_controllers中:
appname/app/controllers/line_items_controller.rb appname / app / controllers / line_items_controller.rb
class LineItemsController < ApplicationController
include CurrentCart
but it produces this error when i try to execute on my browser: 但是当我尝试在浏览器上执行时会产生此错误:
uninitialized constant LineItemsController::CurrentCart
app/controllers/line_items_controller.rb:2:in `<class:LineItemsController>'
app/controllers/line_items_controller.rb:1:in `<top (required)>'
Nothing seems to be wrong here, if we are talking about Rails 4 - it should work out of the box. 如果我们在谈论Rails 4,那么这里似乎没有什么错-它应该开箱即用。
However, what you are doing is a slight misuse of what concerns are for. 但是,您正在做的是对所关注问题的轻微滥用。 And you are defining models/concerns
, where you should put this one in controllers/concerns
(for readability's sake). 并且您正在定义models/concerns
,应该将其放在controllers/concerns
(出于可读性controllers/concerns
)。
For this case, controller filters are more suitable. 对于这种情况, 控制器过滤器更为合适。
class LineItemsController < ApplicationController
before_action :set_cart
private
def set_cart
@cart = Cart.find(session[:cart_id])
rescue ActiveRecord::RecordNotFound
@cart = Cart.create
session[:cart_id] = @cart.id
end
end
Based on the code, I'm assuming you are following along with the book, "Agile Web Development with Rails." 根据代码,我假设您正在跟着《用Rails进行敏捷Web开发》这本书。
I would recommend just moving your code from: 我建议您将代码从以下位置移开:
appname/app/models/concerns/current_cart.rb
to: 至:
appname/app/controllers/concerns/current_cart.rb
This would allow you to most easily follow the example in the book. 这将使您最轻松地遵循本书中的示例。
Was having the same problem. 有同样的问题。 For me it was a simple bug. 对我来说,这是一个简单的错误。 It couldn't read LineItemsController::CurrentCart
because when I created current_cart.rb
it was saved with an aditional white space at the end (after .rb), .eg current_cart.rb(space)
它无法读取LineItemsController::CurrentCart
因为当我创建current_cart.rb
它的末尾带有附加空白(.rb之后),例如._current_cart.rb current_cart.rb(space)
So after deleting the white extra space it all worked out well. 因此,删除白色多余的空格后,一切都很好。
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