Firebase CORS - 未处理的错误类型错误：无法读取未定义的属性来源答案

【问题标题】：Firebase CORS - Unhandled error typeError: Cannot read property origin of undefinedFirebase CORS - 未处理的错误类型错误：无法读取未定义的属性来源
【发布时间】：2021-10-16 20:34:55
【问题描述】：

目前正在尝试直接从我的 web 应用程序中使用 google 云功能，该功能会进行 mongodb 查询并将数据返回到客户端浏览器。我收到以下错误。

i  functions: Beginning execution of "us-central1-fullName"
>  {"verifications":{"app":"MISSING","auth":"MISSING"},"logging.googleapis.com/labels":{"firebase-log-type":"callable-request-verification"},"severity":"INFO","message":"Callable request verification passed"}
>  {"severity":"ERROR","message":"Unhandled error TypeError: Cannot read property 'origin' of undefined\n    at C:\\Users\\myalt\\s\\functions\\node_modules\\cors\\lib\\index.js:219:40\n    at optionsCallback (C:\\Users\\myalt\\s\\functions\\node_modules\\cors\\lib\\index.js:199:9)\n    at corsMiddleware (C:\\Users\\myalt\\s\\functions\\node_modules\\cors\\lib\\index.js:204:7)\n    at C:\\Users\\myalt\\s\\functions\\index.js:6:5\n    at newHandler (C:\\Users\\myalt\\AppData\\Roaming\\npm\\node_modules\\firebase-tools\\lib\\emulator\\functionsEmulatorRuntime.js:296:16)\n    at C:\\Users\\myalt\\s\\functions\\node_modules\\firebase-functions\\lib\\common\\providers\\https.js:322:32\n    at processTicksAndRejections (internal/process/task_queues.js:93:5)"}
i  functions: Finished "us-central1-fullName" in ~1s

我最初收到此错误：

Access to fetch at 'https://us-central1--8955f.cloudfunctions.net/fullName' from origin 'https://-8955f.web.app' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

但是，我通过添加解决了这个问题

const cors = require('cors')({ Origin: true });

exports.fullName = functions.region('us-central1').https.onCall((req, res) => {
    cors(req, res, () => {
// my function
}

我不完全确定为什么会发生此起源错误。任何帮助将不胜感激。

const cors = require('cors')({ Origin: true });

exports.fullName = functions.region('us-central1').https.onCall((req, res) => {
    cors(req, res, () => {
        return new Promise((resolve, reject) => { // ???? return a promise, so Cloud Functions knows to wait
            var MongoClient = require('mongodb').MongoClient;
            var url = "mongodb://:/?readPreference=primary&appname=MongoDB%20Compass&ssl=false";
            MongoClient.connect(url, function (err, db) {
                console.log('Connected to database.')
                if (err) throw err;
                var dbo = db.db("discord_pandemic");
                dbo.collection("ArrayStats").find().toArray(function (err, result) {
                    if (err) throw err;
                    const totalInfections = result[0].total_infections
                    const totalUsers = result[0].total_users
                    const totalCommands = result[0].total_commands
                    const totalLiveInfections = result[0].total_live_infections
                    const totalLiveInfectedChannels = result[0].total_live_infected_channels
                    const data = {
                        totalInfections: totalInfections,
                        totalUsers: totalUsers,
                        totalCommands: totalCommands,
                        totalLiveInfections: totalLiveInfections,
                        totalLiveInfectedChannels: totalLiveInfectedChannels
                    }
                    resolve(data); // ???? resolve the promise with the data for the user
                });
            });
        });
    })
})

【问题讨论】：

标签： node.js firebase google-cloud-platform

【解决方案1】：

错误消息：“TypeError: Cannot read property 'origin' of undefined”表示在您的代码中您正在调用属性：代码/状态，而此属性为 NULL。这可能是回调混淆，例如here，其中提到是因为 send 可能没有返回承诺，而是使用回调方法。另一方面，这可能只是缺少像here 或here 这样的定义。不确定您之前是否检查过共享链接，但如果没有，我建议您检查一下。

【讨论】：