问题描述
我正在使用 javascript 为 firebase 编写云函数，但我被卡住了，我不知道错误的确切含义并且无法解决它..错误状态:27:65 错误每个 then() 应该返回一个值或抛出 promise/always-return
I am writing a cloud function for firebase using javascript but I am stuck, I don't know the exact meaning of error and unable to solve it..The error states: 27:65 error Each then() should return a value or throw promise/always-return
'use strict'
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
exports.sendNotification = functions.database.ref('/notifications/{user_id}/{notification_id}').onWrite((change, context) => {
const user_id = context.params.user_id;
const notification_id = context.params.notification_id;
console.log('We have a notification from : ', user_id);
if (!change.after.val()) {
return console.log('A Notification has been deleted from the database : ', notification_id);
}
const deviceToken = admin.database().ref(`/ServiceProvider/${user_id}/device_token`).once('value');
return deviceToken.then(result => {
const token_id = result.val();
const payload = {
notification: {
title : "New Friend Request",
body: "You Have Received A new Friend Request",
icon: "default"
}
};
return admin.messaging().sendToDevice(token_id, payload).then(response => {
console.log('This was the notification Feature');
});
});
});
推荐答案
改变这个:
return admin.messaging().sendToDevice(token_id, payload).then(response => {
console.log('This was the notification Feature');
});
为此:
return admin.messaging().sendToDevice(token_id, payload).then(response => {
console.log('This was the notification Feature');
return null; // add this line
});
then 回调只需要返回一个值.
The then callback just needs to return a value.
然而，eslint 可能会抱怨代码中嵌套的 then()，这也是一种反模式.您的代码的结构应该更像这样:
However, eslint may then complain about nested then() in your code, which is also an anti-pattern. Your code should really be structured more like this:
const deviceToken = admin.database().ref(`/ServiceProvider/${user_id}/device_token`).once('value');
return deviceToken.then(result => {
// redacted stuff...
return admin.messaging().sendToDevice(token_id, payload);
}).then(() => {
console.log('This was the notification Feature');
});
请注意，每个然后相互链接，而不是相互嵌套.
Note that each then chains off of each other, rather than being nested inside each other.
这篇关于每个 then() 都应该返回一个值或抛出 Firebase 云函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！