具有来自Firebase

Question

我是本机反应的初学者，我正在尝试开发购物应用程序。当我尝试从db firebase读取客户订单时，无法到达产品，并且显示未定义。

这是我的代码

export default class Orders extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
        arrData:[]
    };
}
  componentDidMount = () => {
    var ref = database.ref('orders'); 

    ref.once('value').then(snapshot => {
        console.log('Orders',snapshot.val());

         // get children as an array
         var items = [];
         snapshot.forEach((child) => {
           items.push({
              id: child.val().id,
              customer: child.val().customerId,
              products:JSON.stringify([child.val().products]),
           });
        });

        this.setState({ arrData: items});
        //console.log(items);
    });
  }

  renderItem = ({item, index}) => (
    <TouchableOpacity
      style={styles.listItem}>
      <View style={styles.view}>
        <Text style={styles.text}>{item.customer}</Text>
      </View>
    </TouchableOpacity>
  )

render()
{
  return(
    <View style={{flex: 1}}>
      <FlatList
        //refreshing={this.state.refresh}
        //onRefresh={this.loadNew}
        data={this.state.arrData}
        keyExtractor={(item, index) => index.toString()}
        style={{flex:1, backgroundColor:'#eee'}}
        renderItem={this.renderItem}
        //onEndReached={this.handleLoadMore}
        onEndThreshold={0}
        />
    </View>
  )
}
}

我试图更改此行

var ref = database.ref('orders'); 

进入此

var ref = database.ref('orders').child(myOrders); 

但是我在控制台中得到了（空）