Firebase数据库触发器-在删除和更新时触发onCreate

我有三个Firebase数据库触发器功能，可以将通知推送给用户。但是，我注意到.onCreate（）在数据库更新和删除时被触发。这是预期的吗？有办法防止这种情况吗？

const functions = require('firebase-functions')

exports.onNoteCreate = functions
.region('europe-west1')
.database
.ref('/notes/{noteId}')
.onCreate((snapshot, context) => {
  ...
  //Push notification to affected users

  //Compose notification object
  const notificationObject = { "test": true }
  membersToAlert.forEach((memberId, index) => {
    let isAlreadyPresent = false
    //Do not write if already present! - This code should not be needed?
    const ref = snapshot.ref.root.child(`/notes/${personId}/noteAdditions`)
    ref.orderByChild('originId')
      .equalTo(noteId)
      .on("value", (removeSnapshot) => {
        isAlreadyPresent = true
      })
    //Write notification to all affected users
    if(!isAlreadyPresent) {
      snapshot.ref.root.child(`/notifications/${personId}/noteAdditions`).push(notificationObject)
    }
  })
  return true
})

我的.onUpdate（）和.onDelete（）触发器也正在监听.ref（'/ notes / {noteId}'）。那是问题吗？

如何确保.onCreate（）仅在插入新对象时被触发？

编辑：

我的测试工作流程如下：

1. 使用.push（）在/ notes中创建一个新节点->按预期工作

2. 使用.update（）更新同一节点->按预期工作

3. 直接从Firebase控制台删除/ notes / {noteId}中的节点

步骤3触发器既.onCreate（）和.onUpdate（）。请参阅以下日志：

I 2019-08-12T17:17:25.867Z onNoteCreate 670055884755913 onNoteCreate ... onNoteCreate 670055884755913 
I 2019-08-12T17:17:26.053Z onNoteUpdate 670048941917608 onNoteUpdate ... onNoteUpdate 670048941917608 
D 2019-08-12T17:17:26.843878505Z onNoteDelete 670054292162841 Function execution started onNoteDelete 670054292162841 
D 2019-08-12T17:17:26.849773576Z onNoteDelete 670054292162841 Function execution took 7 ms, finished with status: 'ok' onNoteDelete 670054292162841

删除前的数据库

-notifications
  -userId
    -noteAdditions
      -guid01
        -notificationData
    -noteUpdates
      -guid03
        -notificationData

删除后的数据库

//guid01 gets deleted by .onDelete() as expected
//guid03 gets deleted by .onDelete() as expected

-notifications
  -userId
    -noteAdditions
      -guid02
        -notificationData //Inserted by .onCreate() upon delete
    -noteUpdates
      -guid04
        -notificationData //Inserted by .onUpdate() upon delete

侦听器附加到/ notes / {noteId}，并且正在/ notifications / {userId} /进行更新。

onNoteCreate

exports.onNoteCreate = functions
.region('europe-west1')
.database
.ref('/notes/{noteId}')
.onCreate((snapshot, context) => {
  ...
  snapshot.ref.root.child(`/notifications/${personId}/noteAdditions`).push(notificationObject)
  ...
  console.log('onNoteCreate', '...')
  ...
})

onNoteUpdate

exports.onNoteUpdate = functions
.region('europe-west1')
.database
.ref('/notes/{noteId}')
.onUpdate((change, context) => {
  ...
  change.after.ref.root.child(`/notifications/${personId}/noteUpdates`).push(notificationObject)
  ...
  console.log('onNoteUpdate', '...')
  ...
})

这样导入函数是否重要？

const create = require('./src/db-functions/notes').onNoteCreate
const update = require('./src/db-functions/notes').onNoteUpdate
const delete = require('./src/db-functions/notes').onNoteDelete
exports.onNoteCreate = create
exports.onNoteUpdate = update
exports.onNoteDelete = delete