预期的catch()或返回(承诺/捕获或返回) [英] Expected catch() or return (promise/catch-or-return)

问题描述

我是JavaScript的新手.这是我在javascript中将第一个功能部署在firebase上的第一个功能.

I am new to JavaScript.This is my first function in javascript to deploy a function on the firebase.

收到此错误:

 - [eslint] Unexpected function expression. (prefer-arrow-callback)
 - [eslint] Expected catch() or return (promise/catch-or-return)

此功能有什么问题?

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.grantSignupReward = functions.database.ref('/users/{uid}/last_signin_at')
  .onCreate(event => {
  var uid = event.params.uid;

  admin.database().ref('users/${uid}/referred_by')
    .once('value').then(function(data) {
    var referred_by_somebody = data.val();

    if (referred_by_somebody) {
      var moneyRef = admin.database()
      .ref('/users/${uid}/inventory/pieces_of_eight');

      moneyRef.transaction(function(current_value) {
        return (current_value || 0) + 50;
      });
    }
  });
});

推荐答案

第一个错误建议您使用箭头函数作为回调.因此，您需要将常规函数(function(){...})替换为箭头函数((()=> {...})

The first error suggests you to use an arrow function as a callback. So you need to replace the regular functions, (function() { ... }), with arrow functions, (() => { ... }).

第二个错误表明您要么需要拒绝承诺，要么返回承诺本身.我对您的代码不太确定，但是我相信这种方法:

The second error suggests that you either need to catch the promise rejection, or return the promise itself. I am not too sure about your code but I believe that this method:

admin.database().ref('users/${uid}/referred_by').once('value')

兑现承诺.因此，需要像这样返回它:

returns a promise. So it needs to be returned like this:

return admin.database().ref('users/${uid}/referred_by').once('value')

或处理如下错误:

admin.database().ref('users/${uid}/referred_by').once('value')
  // ... your code here
  .catch(error => { ... });

正如@Bergi在评论中指出的那样，此处不希望返回承诺，您可以在承诺中添加 catch 块.

As @Bergi pointed out in the comments that returning the promise is not preferable here, you may just add a catch block to your promise.

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