从控制器以JSON呈现对象时，如何包含对象父级的字段？

Question

I'm using Rails 4.2.7. When returning an object via a show method, I want to include an object from the object's parent. I tried

  def show
    respond_to do |format|
      @my_object = MyObject.find(params[:id])
      format.json { render :json => @my_object.to_json(:include => [:parent, :include => :address]) }
    end
  end

However this is producing the error

NoMethodError (undefined method `include' for #<MyObject:0x007fa1b433d788>):

What's the right way to include an object from my parent?

here's the parent model in my Rails app

class Parent < ActiveRecord::Base
  belongs_to :address, :autosave => true   #, dependent: :destroy

Answer 1

Try this one

def show

  @my_object = MyObject.find(params[:id])
  render :json => @my_object.to_json(:include => [:parent => {:include => :address}]) 

end

You have added include within the include statement,

@my_object.to_json(:include => [:parent, **:include** => :address])

so rails is searching include as one of the method or model.

You can use a array like this for including more than one relationship.

:include => [:parent, :address]