如何检查给定的@current_user是否已经写了“评论”？

For my model Vendor:

对于我的模型供应商:

:has_many Review

And Each User:

每个用户:

:has_many Review

And Each Review:

每个评论:

:belongs_to Vendor
:belongs_to User

So. I don't one a User to be able to write more than one Review, so I want to do a check on the vendors/:vendorId URL which is the "show" action, and have a way to make the "Write Review" button disappear or appear based on whether for the @current_user there has already been written a Review for that specific Vendor.

所以。我不是一个用户能够写一个以上的评论,所以我想检查供应商/:vendorId URL这是“显示”操作,并有办法进行“写评论”按钮消失或显示基于是否已为@current_user编写了针对该特定供应商的评论。

I know the @vendor.id and @loggedin_user.id but not sure how to do a find on two parameters.

我知道@ vendor.id和@ loggedin_user.id,但不知道如何对两个参数进行查找。

1 个解决方案

#1

There are lots of ways to do this. If you just want to find on two parameters, you can do:

有很多方法可以做到这一点。如果您只想查找两个参数,可以执行以下操作:

Review.find(:first, :conditions => {:user_id => @user.id, :vendor_id => @vendor.id})

You can also make use of the associations, like the following:

您还可以使用关联,如下所示:

@current_user.reviews.find(:first, :conditions => {:vendor => @vendor})

A named_scope would be another way:

named_scope将是另一种方式:

class Review < ActiveRecord::Base
  named_scope :for_vendor, lambda {|vendor| 
    {:conditions => {:vendor => vendor}}
  }
  belongs_to :vendor
  belongs_to :user
end

@current_user.reviews.for_vendor(@vendor).empty?

Since it's a business rule, I'd recommend encapsulating this logic in a method on either User or Vendor, like:

由于这是一个业务规则,我建议将此逻辑封装在用户或供应商的方法中,如:

def can_review?(vendor)
  self.reviews.find(:first, :conditions => {:vendor => @vendor}).nil?
end

You could then do, in the view:

然后你可以在视图中做到:

<%= review_vendor_button if @current_user.can_review?(@vendor) %>

#1