[英]Reusing model in ruby on rails application
I'm currently in the process of adding comments to one of my models MaintenanceRequest
and wondering how I should go about this.我目前正在向我的一个模型MaintenanceRequest
添加评论,并想知道我应该如何处理这个问题。
I have a model Offer
which already has comments built and it is set up with ActionCable as follows我有一个模型Offer
已经建立了评论,它是用 ActionCable 设置的,如下所示
# models/comment.rb
class Comment < ApplicationRecord
belongs_to :user
belongs_to :offer
end
# channels/comment_channel.rb
class CommentChannel < ApplicationCable::Channel
def subscribed
offer = Offer.find params[:offer]
stream_for offer
end
end
and the comment controller looks as并且评论控制器看起来像
# controllers/comments_controller.rb
class CommentsController < ApplicationController
before_action :authenticate_user!
before_action :is_valid_offer
def create
offer = Offer.find(comment_params[:offer_id])
if comment_params[:content].blank?
# return redirect_to request.referrer, alert: 'Comment cannot be empty.'
return render json: {success: false}
end
if offer.user_id != current_user.id && offer.landlord_id != current_user.id
return render json: {success: false}
end
@comment = Comment.new(
user_id: current_user.id,
offer_id: offer.id,
content: comment_params[:content],
)
if @comment.save
# redirect_to request.referrer, notice: 'Comment sent.'
CommentChannel.broadcast_to offer, message: render_comment(@comment)
render json: {success: true}
else
redirect_to request.referrer, alert: "Couldn't send comment."
render json: {success: true}
end
end
end
My question is that is there a way I could use the same model for comments belonging to MaintenanceRequest
or should I just create new model and controller for there comments?我的问题是,有没有一种方法可以对属于MaintenanceRequest
评论使用相同的模型,还是应该为评论创建新模型和控制器? It would seem that this would get quite messy if I tried to reuse the current comment model.如果我尝试重用当前的评论模型,这似乎会变得非常混乱。 What would be the "best practice" here?这里的“最佳实践”是什么?
If you want to make a resuable assocation you want to use a polymorphic assocation:如果要创建可重用关联,则要使用多态关联:
class Comment < ApplicationRecord
belongs_to :user
belongs_to :commentable,
polymorphic: true
validates :content,
presence: true
end
Instead of using a single column holding an integer pointing to a fixed table this "cheats" the relation database model by using a one column for the other tables primary key and storing the class name of the entitity in a string column (in this example called commentable_type
).不是使用包含指向固定表的整数的单个列,而是通过使用一列作为其他表的主键并将实体的类名存储在字符串列中(在本例中称为commentable_type
)。
You can create the needed columns by passing the polymorphic option when generating the migration (or model):您可以通过在生成迁移(或模型)时传递多态选项来创建所需的列:
rails g migration add_commentable_to_comments commentable:belongs_to{polymorphic}
However that controller action is a bit of train wreck.然而,控制器的动作有点像火车失事。 It should look more like this:它应该看起来更像这样:
class CommentsController < ApplicationController
before_action :authenticate_user!
before_action :set_offer
before_action :authorize_user
def create
@comment = @offer.comments.new(comment_params) do |c|
c.user = current_user
end
if @comment.save
# redirect_to request.referrer, notice: 'Comment sent.'
CommentChannel.broadcast_to offer, message: render_comment(@comment)
# rendering json here is actually just stupid. Just use a HTTP status code
# as a response if you're not actually returning the rendered entity.
render json: { success: true },
status: :created,
location: @comment
else
# either return JSON which is actually useful or just a status code
render json: { success: false },
status: :unprocessable_entity
end
end
private
def set_offer
@offer = Offer.find(params[:offer_id])
end
# this should be extracted to an authorization layer such as Pundit
def authorize_offer
if @offer.user_id != current_user.id && @offer.landlord_id != current_user.id
render json: { success: false },
status: :unauthorized
end
end
end
There are two way to resuse this controller for different types of "commentables".有两种方法可以将此控制器重用于不同类型的“评论”。 You can either check for the presence of the offer_id
or maintenance_request_id
in a single controller and use that to deduce the class or you can use inheritance to destribute the responsibilities better:您可以检查单个控制器中是否存在offer_id
或maintenance_request_id
并使用它来推断类,或者您可以使用继承来更好地分配职责:
# routes.rb
resources :offers do
resources :comments,
only: :create,
module: :offers
end
resources :maintainence_requests do
resources :comments,
only: :create,
module: :maintainence_requests
end
class CommentsController
before_action :set_commentable, only: [:new, :create, :index]
before_action :authenticate_user!
attr_reader :commentable
def create
@comment = commentable.comments.new(comment_params) do |c|
c.user = current_user
end
if @comment.save
# simple extendability feature that lets you "tap into" the flow
# by passing a block when calling super in subclasses
yield @comment if block_given?
render json: @comment,
status: :created
else
render json: { errors: @comment.errors.full_messages },
status: :unprocessable_entity
end
end
private
# Uses simple heuristics based on module nesting to guess the name of the model
# that is being commented upon. Overide if needed.
# @example Foos::BarsController -> Foo
def commentable_class
@commentable_class ||= self.class.module_parent.name.singularize.constantize
end
def commentable_param_key
commentable_class.model_name.param_key
end
def set_commentable
@commentable = commentable_class.find("#{commentable_param_key}_id")
end
def comment_params
params.require(:comment)
.permit(:content)
end
end
module Offers
class CommentsController < ::CommentsController
# POST /offers/:offer_id/comments
def create
# block is called after a comment is succesfully saved but before
# the response is set
super do |comment|
CommentChannel.broadcast_to comment.offer,
message: render_comment(comment)
end
end
end
end
module MaintainenceRequests
class CommentsController < ::CommentsController
end
end
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