javascript - 使用 firebase 数据填充下拉字段

Question

我在控制台中获取值，但无法在下拉列表中显示 See this link

谁能解释一下我在这里做错了什么

        return firebase.database().ref('Users/Trainers/').on('value', (snapshot) => {
            snapshot.forEach(function(childSnapshot){
                // var childKey= childSnapshot.key;
                var childData= childSnapshot.val();
                var childEmail = childData.email;
                var childfirstName = childData.firstName;
                var childlastName = childData.lastName;
                var childTrainers = childfirstName + ' ' + childlastName + ' ' + childEmail;
            console.log(childTrainers);
            })
        })
    }

    async componentDidMount(){
        this.getlist();
    }

状态

childTrainers: []

在渲染方法中，

<Select options={this.state.childTrainers} />

Answer 1

尝试从 firebase 获取值时更新状态:

return firebase.database().ref('Users/Trainers/').on('value', (snapshot) => {
    const childTrainerSnapshot = snapshot.map(childSnapshot => {
        return childfirstName + ' ' + childlastName + ' ' + childEmail
    });
    this.setState({ childTrainers: childTrainerSnapshot });
})