Ruby on Rails:选择嵌套模型的所有记录的简单方法? [英] Ruby on Rails: Simple way to select all records of a nested model?

问题描述

很好奇，我花了很多时间来尝试在嵌套模型中获取所有记录的数组.我只想确保没有更好的方法.

Just curious, I spent an embarrassing amount of time trying to get an array of all the records in a nested model. I just want to make sure there is not a better way.

这是设置:

我有三个相互嵌套的模型(设施>>标签>>检查)，为route.rb生成了这样的代码:

I have three models that are nested under each other (Facilities >> Tags >> Inspections), producing code like this for routes.rb:

map.resources :facilities do |facilities|
  facilities.resources :tags, :has_many => :inspections 
end

我想对设施进行所有检查，这就是我的代码最终的结果:

I wanted to get all of the inspections for a facility and here is what my code ended up being:

def facility_inspections
  @facility = Facility.find(params[:facility_id])
  @inspections = []
  @facility.tags.each do |tag| 
    tag.inspections.each do |inspection|
      @inspections << inspection
    end
  end
end

它有效，但这是执行此操作的最佳方法-我认为这很麻烦.

It works but is this the best way to do this - I think it's cumbersome.

推荐答案

您可以使用has_many :through关联.在您的模型中:

You can use has_many :through association. In your models:

# Facility model
has_many :tags
has_many :inspections, :through => :tags

# Tag model
belongs_to :facility
has_many :inspections

您可以得到所有这样的检查:

And you can get all inspections like this:

@inspections = Facility.find(params[:facility_id]).inspections

但是如果您在Facility和Tag之间具有HABTM关系，它将变得更加复杂，并且您将不得不手动编写一些sql，如下所示:

But if you have HABTM relation between Facility and Tag it will be more complicated and you would have to write some sql manualy, like this:

@inspections = Inspection.all(:joins => "INNER JOIN tags ON tags.id = inspections.tag_id INNER JOIN facilities_tags ON tags.id = facilities_tags.tag_id", :conditions => ["facilities_tags.facility_id = ?", params[:facility_id] )

当然，以上代码取决于您的表结构.如果您将显示它，那么给出正确答案将更容易:).希望对您有帮助！

Of course above code depends on your table structure. If you will show it, then it would be easier to give correct answer :). Hope it helps!

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