Rails 具有自定义 REST collection 架构的 ActiveResource？

Question

我正在尝试建立一些在 active_resource gem (ActiveResource)

之上工作的 Rails 模型

module Core
    class RestResource < ActiveResource::Base
        self.format = :json
    end
end

module Core
    module API
        class BaseModel < ::Core::RestResource
        self.site = ENV['API_URI']
        self.headers['Api-Token'] = ENV['API_TOKEN']
        end
    end
end

module Core
    module API
        class MyModel < ::Core::API::BaseModel
        end
    end
end

我正在尝试运行 rails 控制台如下

2.3.1 :001 > MyModel = Core::API::MyModel
 => Core::API::MyModel 
2.3.1 :002 > MyModel.all
ArgumentError: expected an attributes Hash, got ["data", [{"first_name"=>"walter", "last_name"=>"white", "timestamp"=>1478515925}]]
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1377:in `load'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1124:in `initialize'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1051:in `new'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1051:in `instantiate_record'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1047:in `block in instantiate_collection'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/collection.rb:68:in `block in collect!'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/collection.rb:8:in `each'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/collection.rb:8:in `each'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/collection.rb:68:in `collect!'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1047:in `instantiate_collection'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:1016:in `find_every'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:923:in `find'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/bundler/gems/activeresource-f4bec7f8f389/lib/active_resource/base.rb:949:in `all'
    from (irb):2
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/gems/railties-5.0.0.1/lib/rails/commands/console.rb:65:in `start'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/gems/railties-5.0.0.1/lib/rails/commands/console_helper.rb:9:in `start'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/gems/railties-5.0.0.1/lib/rails/commands/commands_tasks.rb:78:in `console'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/gems/railties-5.0.0.1/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
    from /Users/nakwa/.rvm/gems/ruby-2.3.1/gems/railties-5.0.0.1/lib/rails/commands.rb:18:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'
2.3.1 :003 >

在我的 rails 控制台上（rails 为 API 供电的实例）我可以看到

Started GET "/v1/my_model.json" for ::1 at 2016-11-08 16:42:11 +0100
Processing by V1::MyModelController#index as JSON
  MyModel Load (0.2ms)  SELECT "my_model".* FROM "my_model"
[active_model_serializers] Rendered V1::MyModelSerializer with MyModelSerializer::Adapter::Attributes (2.2ms)
Completed 200 OK in 13ms (Views: 2.8ms | ActiveRecord: 1.8ms)

我的理解是 Rails activeresource 期望 JSON API 到 return 类似：

[
  {"first_name": "walter", "last_name": "white"}, 
  {"first_name": "chuck", "last_name": "norris"}
]

当我的 collections 看起来像这样时：

{
  "data": [
    {"first_name": "walter", "last_name": "white"}, 
    {"first_name": "chuck", "last_name": "norris"}
  ],
  "collection": {
    "total_entries": 2
  }
}

我现在正在寻找一种自定义 ActiveResource Collection 解析器的好方法，可能像 backbone.js 正在做的事情 (http://backbonejs.org/#Collection-parse) 但不知何故我找不到这个问题的答案很明显。

有什么想法吗？谢谢！

Answer 1

默认情况下，ActiveResource 对 API 返回的数据格式有非常强烈的期望，但您可以为这种情况提供自己的格式。

任何 Ruby 实现一些预期方法的对象都可以用作格式。 ActiveResource 本身将格式实现为模块，因此我们将坚持这一约定。

作为一个懒人，我将重用标准 JsonFormat 实现并且只覆盖方法 decode:

module CustomJsonFormat
  include ActiveResource::Formats::JsonFormat

  extend self

  def decode(json)
    ActiveSupport::JSON.decode(json)['data']
  end
end

现在我们只是告诉 ActiveResource 子类使用它：

class BaseModel < ActiveResource::Base
  self.format = CustomJsonFormat

  # ... set self.site, self.headers etc.
end

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