React本机Redux对象映射在firebase的动态数据上创建副本

我目前有一个列表，它总是使用“on”监听firebase数据库

除了向数据库中添加新数据外，一切似乎都正常。除非进行刷新，否则数据库中的数据似乎会重复

My action.js：

export const getAllEvents = () => {
    var a =[]
      return (dispatch) => {
        dispatch(fetchingStart());

            var ref = firebase.database().ref('Events/');
            ref.orderByChild("epochTime").on("value", function(snapshot) {

                snapshot.forEach(child => {
                    a.push(child.val())
                })
                console.log("Array dispatch ", a)
                dispatch(fetchingSuccess(a))


              });


      }
  }

我的减速机：

const INITIAL_STATE = {
    arr: [],
    isFetching: false,

}

const eventListReducer = (state = INITIAL_STATE, action) => {
    switch (action.type) {
        case FETCH_BEGIN:
            console.log("begining fetch")
          return { ...state, isFetching: true };
        case FETCH_SUCCESS:
          return { ...state, isFetching: false, arr: action.payload };
        default:
          return state;
      }
}

export default eventListReducer;

我的渲染：

var obj = this.props.eventListReducer;

     {obj.map((request,i) => (
                                <TouchableOpacity activeOpacity={0.8} key={i} onPress={() => this.props.navigation.navigate('Event', {
                                    spots: request.availableSpots,
                                    date: request.date,
                                    puckdrop: request.time,
                                    level: request.level,
                                    organizer: request.scheduler,
                                    uuid: request.uuid,

                                })

                            }>
<Text.........

var obj=this.props.eventListReducer；
{obj.map（（请求，i）=>(
this.props.navigation.navigate（'Event'{
地点：request.availablespot，
日期：request.date，
puckdrop:request.time，
级别：request.level，
组织者：request.scheduler，
uuid:request.uuid，
})
}>
你的控制台上有重复的键警告吗？我以前也有，但后来我添加了{I}键。我用一些传统信息编辑了我的问题