使用React.js检查属性是否存在

我是使用React.js的新手，正在尝试编写一个可重用的组件，该组件具有传递给它的可选属性.在组件中，该可选属性使用流星从数据库中提取数据，然后我要检查返回的对象上是否存在属性(任务上存在parent_task)，如果存在，则添加链接.这似乎很简单，但我不断出错.有人对我可能会缺少的东西有什么建议吗?我是否缺少jsx陷阱?

I'm new to using react.js, and am trying to write a re-usable component that has an optional property passed to it. In the component, that optional property pulls data from a db using meteor, then I want to check if a property exists on the returned object (parent_task exists on task), and if exists, adds a link. This seems fairly simple, but I keep getting errors. Does anyone have any suggestions on what I might be missing? Is there a jsx gotcha that I'm missing?

<Header task={params.task_id} />  // rendering component with property

// Task List Header
Header = React.createClass({
  mixins: [ReactMeteorData],

  getMeteorData() {
    var handle = Meteor.subscribe('tasks');

    return {
      taskLoading: ! handle.ready(),
      task: Tasks.findOne({_id: this.props.task})
    }
  },

  getParentTaskLink() {
    if (!this.data.taskLoading) {
      var current_task = this.data.task;

      if (parent_task in current_task) {  // or current_task.hasOwnProperty(parent_task)
        console.log("parent_task exists!");
      }
    }
  },

  render() {
    return (
      <div className="bar bar-header bar-calm">
        {this.getParentTaskLink()} // eventually return anchor element here
        <h1 className="title">Hello World</h1>
      </div>
    )
  }
});