Rails Action Cable:如何访问ApplicationCable::Channel类中的实例变量?

我认为在定义订阅时不能访问实例变量。但是您可以将product\u id作为参数传递,然后订阅ProductChannel。 https://guides.rubyonrails.org/action_cable_overview.html#subscriber

App.cable.subscriptions.create { channel: "ProductChannel", product_id: your_product_id }

def subscribed
  stream_from "product_channel_#{params[:product_id]}"
end

在您的 subscribed 已订阅

一个例子 exists within the ActionCable codebase

class ProductChannel < ApplicationCable::Channel
  def subscribed
    @product = Product.find(params[:product_id])
    stream_from "room_channel_product_#{@product.id}"
  end

  def unsubscribed
  end

  def foo
    @product.do_stuff
  end
end