Rails：在 to_json(:methods => [:model_method]) 中调用模型方法答案

【问题标题】：Rails: Calling Model methods in to_json(:methods => [:model_method])Rails：在 to_json(:methods => [:model_method]) 中调用模型方法
【发布时间】：2015-09-21 07:17:12
【问题描述】：

我在模型 image_url 和 thumb_url 中定义了两种方法来获得绝对的图像和拇指 url 并在控制器.to_json() 方法中调用它们。

当我查看Json 响应时，它只显示image_url 而不是thumb_url 请指导我在这里做错了什么。

型号：

class Post < ActiveRecord::Base
  include Rails.application.routes.url_helpers

    validates :image, presence: true

      has_attached_file :image, styles: { :medium => "640x", thumb: "100x100#" } # # means crop the image
        validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/

  def image_url
   relative_path =  image.url(:medium)
   self.add_host_prefix relative_path
  end

 def thumb_url
   relative_path = image.url(:thumb)
   self.add_host_prefix relative_path
 end

  def add_host_prefix(url)
    URI.join(root_url, url).to_s
  end
end

控制器：

class Api::ImagesController < ApplicationController

  def index
    @posts =  Post.all.order(id: :desc)
    paginated_records = @posts.paginate(:page => params[:page], :per_page => params[:per_page])
    @posts = with_pagination_info( paginated_records )
    render :json => @posts.to_json(:methods => [:thumb_url], :methods =>[:image_url])
  end
end

这是我的 Json 响应：

"data": [{
"id": 23,
"caption": "World Top View",
"created_at": "2015-09-17T14:10:57.278Z",
"updated_at": "2015-09-17T14:10:57.278Z",
"image_file_name": "world.topo.bathy.200401.3x21600x10800.jpg",
"image_content_type": "image/jpeg",
"image_file_size": 29698041,
"image_updated_at": "2015-09-17T14:10:36.975Z",
"image_url": "http://localhost:3000/system/posts/images/000/000/023/medium/world.topo.bathy.200401.3x21600x10800.jpg?1442499036"}

【问题讨论】：

标签： ruby-on-rails json activerecord

【解决方案1】：

您不能将两个 :methods 键传递到哈希中，只会使用最后一个键。请记住，散列的键必须是唯一的。如果你想要多种方法，你应该这样做......

render :json => @posts.to_json(:methods => [:thumb_url, :image_url])

【讨论】：