Ruby on rails AngularJS中的嵌套表单字段

我正在开发一个带有远程Rails后端的AngularJS应用程序，用于注册体育赛事。除了注册为一名跑步者外，用户还应该能够提交4名跑步者的接力队注册

Rails后端结构：

class Relay < ActiveRecord::Base
  has_many :registrations
  accepts_nested_attributes_for :registrations
end

class Registration < ActiveRecord::Base
  belongs_to :relay
end

class API::RelaysController < API::BaseController
  def create
    @relay = Relay.new(relay_params)
    if @relay.save
      render json: @relay, status: :created#, location: @relay
    else
      render json: @relay.errors, status: :unprocessable_entity
    end
  end
end

relay-create.html：

<form name="form" ng-submit="submit()" class="form-horizontal" novalidate>
  <div ng-repeat="registration in relay.registrations_attributes" ng-form="registration_form" class="well">
    ...
    <div class="form-group">
      <label class="control-label col-sm-4">
        Firstname
      </label>
      <div class="input-group col-sm-7">
        <input class="form-control" ng-model="registrations_attributes.runner_firstname" type="text">
      </div>
    </div>
    ...
  </div>
</form>

...
名字
...

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我需要遵循哪些步骤才能获得一个表单，其中嵌套字段在AngularJS中运行，就像我在Rails中创建的表单一样？不确定嵌套是什么意思，是否有错误？在Rails的中继表单中，我为每个相应的注册使用了一个fields_标记，这意味着当用户提交一个新的中继团队时，四个注册（每个运行者）理想情况下，从angular提交到rails后端的json应该是：{“relay”：{name:“relay XYZ”，registrations_属性[{runner_firstname:“First runner”…}，{runner_firstname:“Second runner”…}，等等。]}

rilaServices.factory('Registration', ['$resource',
  function($resource){
    return $resource('http://localhost:3000/api/registrations/:id', { id: "@id" }, {
      'create':  { method: 'POST' }
    });
  }
 ]);

rilaServices.factory('Relay', ['$resource',
  function($resource){
    return $resource('http://localhost:3000/api/relays/:id', { id: "@id" }, {
      'create':  { method: 'POST' }
    });
  }
 ]);

<form name="form" ng-submit="submit()" class="form-horizontal" novalidate>
  <div ng-repeat="registration in relay.registrations_attributes" ng-form="registration_form" class="well">
    ...
    <div class="form-group">
      <label class="control-label col-sm-4">
        Firstname
      </label>
      <div class="input-group col-sm-7">
        <input class="form-control" ng-model="registrations_attributes.runner_firstname" type="text">
      </div>
    </div>
    ...
  </div>
</form>