then() 返回一个值，仍然有一个返回错误

Question

>我遇到了一个小问题，错误日志说

21:10  warning  Avoid nesting promises                      promise/no-nesting
36:12  warning  Avoid nesting promises                      promise/no-nesting
36:66  error    Each then() should return a value or throw  promise/always-return

它正在谈论的错误放在底部

 return admin.messaging().sendToDevice(token_id,payload).then(theResult =>{
                    console.log("then is returned");
                });

尽管消息非常简单，调试应该没有太大问题(即使是像我这样的新手(，但我无法真正解决它，我甚至尝试删除此功能，但仍然没有成功部署。我寻找了一些类似的问题，但失败了。我将非常感谢任何帮助，谢谢。

exports.sendNotification = functions.firestore.document("Users/{user_id}/Notifications/{notification_id}").onWrite(event=>
{
    const user_id = event.params.user_id;
    const notification_id = event.params.notification_id;
    //console.log("User ID:" + user_id + "Notification ID : "+ notification_id);
    return admin.firestore().collection("Users").doc(user_id).collection("Notifications").doc(notification_id).get().then(queryResult => 
    {
        const from_user_id = queryResult.data().from;
        const from_message = queryResult.data().message;
        const from_data = admin.firestore().collection("Users").doc(from_user_id).get();
        const to_data = admin.firestore().collection("Users").doc(user_id).get();
        return Promise.all([from_data,to_data]).then(result=>
        {
            const from_name = result[0].data().name;
            const to_name = result[1].data().name;
            const token_id = result[1].data().token_id;
            const payload = {
              notification: {
                    title : "Nowa wiadomość od:" + from_name,
                    body : from_message,
                    icon : "default"
                }
            };
                return admin.messaging().sendToDevice(token_id,payload).then(theResult =>{
                    console.log("then is returned");
                });
        });

    });
});

Answer 1

您可以更新.then()块，如下所示：

.then(theResult => console.log("then is returned"));

• always-return：每个then()都需要返回，以便创建可读和可重用的 Promise 链。