我正在尝试从 Firebase 实时数据库中获取餐厅列表，
我的代码片段用于获取数据 -

_isMounted = false;

state :{
  data: [],
}

constructor(props){
  super(props)

  this.state = {
    data:[],
  }
}

componentDidMount(){
  this._isMounted = true
  this.getData()
}

componentWillUnmount(){
  this._isMounted = false
}

getData(){
  firebase.database().ref('Restaurants/').on("value", snapshot =>{
    let restaurantList = snapshot.val();
    console.log(restaurantList)
    this.setState({data: restaurantList})
  });
}

Firebase 上的数据结构如下 -

数组 restaurantList 的控制台输出为 -

Array [
  undefined,
  Object {
    "location": "Testing data",
    "name": "Time Traveller",
    "rating": 4.5,
    "tags": "Indian, Asian",
  },
  Object {
    "locations": "Testing data",
    "name": "Novelty",
    "rating": 4.5,
    "tags": "Indian",
  },
]

我不确定从哪里获取数组中的 undefined 项。