云功能和具有幂等性的Firebase Firestore [英] Cloud functions and Firebase Firestore with Idempotency

问题描述

我正在使用带有Cloud Functions的Beta版本的Firestore.在我的应用程序中，我需要触发一个函数，该函数侦听/company/{id}/point/{id}处的onCreate事件并执行插入(collection('event').add({...}))

I'm using Firestore at beta version with Cloud Functions. In my app I need to trigger a function that listens for an onCreate event at /company/{id}/point/{id} and performs an insert (collection('event').add({...}))

我的问题是:带Firestore的云功能需要幂等函数.我不知道如何确保如果函数在同一事件中连续触发两次，则不会添加具有相同数据的两个文档.

My problem is: Cloud Functions with Firestore require an idempotent function. I don't know how to ensure that if my function triggers two times in a row with the same event, I won't add two documents with the same data.

我发现context.eventId可以解决该问题，但是我不知道使用它的方法.

I've found that context.eventId could handle that problem, but I don't recognize a way to use it.

exports.creatingEvents = functions.firestore
  .document('/companies/{companyId}/points/{pointId}')
  .onCreate((snap, context) => {

    //some logic...

    return db.doc(`eventlog/${context.params.companyId}`).collection('events').add(data)
})

推荐答案

两件事:

1. 首先检查您的集合，以查看文档中是否具有值为context.eventId的属性.如果存在，则在函数中不执行任何操作.
2. 如果尚无具有事件ID的文档，请将context.eventId的值放在您添加的文档的属性中.

1. First check your collection to see if a document has a property with the value of context.eventId in it. If it exists, do nothing in the function.
2. If a document with the event id doesn't already exist, put the value of context.eventId in a property in the document that you add.

这应该防止针对给定事件ID多次调用该函数添加多个文档.

This should prevent multiple invocations of the function from adding more than one document for a given event id.

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