firebase 云 function 对文档执行多项操作时如何正确使用'return'

Question

我试图了解如何正确使用云 function..

a 下面的云 function 达到了预期的结果，但是，我没有在其中使用“返回”。

这是一个问题吗？ 如果是，我该如何解决？

exports.onJobChangeToClosedAndSubstateIsCancelled = functions.firestore
    .document("job/{docId}")
    .onUpdate(async (change, eventContext) => {
        const afterSnapData = change.after.data();
        const afterJobState = afterSnapData["Job state"];
        const afterJobSubState = afterSnapData["Job substate"];

        if (afterJobSubState == "Cancelled" && afterJobState == "Closed") {

            // get all job related job applications
            const relatedJobApplicationsList = await admin.firestore().collection("job application").where("Job id", "==", change.before.id).get();
            // mark job applications closed so that other contractors cant waste their time
            relatedJobApplicationsList.forEach(async doc => {

                await admin.firestore().collection("job application").doc(doc.id).update({
                    "Job application state": "Closed",
                    "Job application substate": "Job cancelled by client",
                })

            })


        }
    });

我从其他问题（例如下面的问题）中的理解是，我应该返回对文档的更改或正在发生的操作。 （这是正确的吗？） 你能帮我吗？-firebase-function-onUpdate

下面是云 function 的示例，我可以在其中放置“return”语句：

// when a chat message is created
// send a notification to the user who is on the other side of the chat
// update the chat 'Chat last update' so that the Chats screen can put the chat at the top of the page
exports.onChatMessageCreate = functions.firestore
    .document("chat messages/{docId}")
    .onCreate(async (snapshot, context) => {
        const snapData = snapshot.data();
        // information about who sent the message
        const senderUserName = snapData["Chat message creator first name"];
        const senderUserId = snapData["User id"];
        // chat id to which chat messages belong to
        const chatId = snapData["Chat id"];

        // information about who should receive the message
        let receiverUserId;
        let receiverToken = "";

        // fetch user to send message to
        const chatData = await (await admin.firestore().collection("chat").doc(chatId).get()).data();
        const chatUsersData = chatData["User ids list"];

        chatUsersData[0] == senderUserId ? receiverUserId = chatUsersData[1] : receiverUserId = chatUsersData[0];

        receiverToken = await (await admin.firestore().collection("user token").doc(receiverUserId).get()).data()["token"];

        console.log("admin.firestore.FieldValue.serverTimestamp()::   " + admin.firestore.FieldValue.serverTimestamp());

        // set chat last update
        await admin.firestore().collection("chat").doc(chatId).update({
            "Chat last update": admin.firestore.FieldValue.serverTimestamp(),
        });

        const payload = {
            notification: {
                title: senderUserName,
                body: snapData["Chat message"],
                sound: "default",
            },
            data: {
                click_action: "FLUTTER_NOTIFICATION_CLICK",
                message: "Sample Push Message",
            },
        };

        return await admin.messaging().sendToDevice(receiverToken, payload);
    });

Answer 1

这是一个问题吗？

是的，如果不返回 Promise（或一个值，因为您的回调 function 是async的），您就错误地管理了 Cloud Function 的生命周期。

在您的情况下，由于您有一个 if 块，最简单的方法就是return null; （或return 0;或return; ）在 CF 的末尾，如下所示。

此外，您需要使用Promise.all() ，因为您希望并行执行对异步方法的可变数量的调用。

exports.onJobChangeToClosedAndSubstateIsCancelled = functions.firestore
    .document("job/{docId}")
    .onUpdate(async (change, eventContext) => {
        const afterSnapData = change.after.data();
        const afterJobState = afterSnapData["Job state"];
        const afterJobSubState = afterSnapData["Job substate"];

        if (afterJobSubState == "Cancelled" && afterJobState == "Closed") {

            // get all job related job applications
            const relatedJobApplicationsList = await admin.firestore().collection("job application").where("Job id", "==", change.before.id).get();
            
            // mark job applications closed so that other contractors cant waste their time
            const promises = [];

            relatedJobApplicationsList.forEach(doc => {

                promises.push(admin.firestore().collection("job application").doc(doc.id).update({
                    "Job application state": "Closed",
                    "Job application substate": "Job cancelled by client",
                }));

            })

            await Promise.all(promises);
        }
        
        return null;
    });

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文档中有关如何正确管理 CF 生命周期 的更多信息。

您可能还会对我在 2021 年I/O Extended UK & Ireland 活动中的演讲感兴趣。这次演讲专门针对这个主题。