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Firestore: CollectionReference.withConverter(converter).add(data) invokes converter.toFirestore twice #3742

hecateball opened this issue Sep 4, 2020 · 1 comment · Fixed by #3755


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hecateball commented Sep 4, 2020

[REQUIRED] Describe your environment

  • Operating System version: macOS Catalina 10.15.6
  • Browser version: N/A
  • Firebase SDK version: 7.19.1
  • Firebase Product: firestore

[REQUIRED] Describe the problem

firebase.firestore().collection('...').withConverter(converter).add(data) invokes converter.toFirestore twice while firebase.firestore().collection('...').withConverter(converter).doc().set(data) invokes converter.toFirestore only once.
Is this intended behavior?

Although this is not a desirable style of processing, if the toFirestore() process has a side effect on the input value, the second invocation fails (See example below).

Steps to reproduce:

try to run following code please.

Relevant Code:

const firebase = require('firebase')

// Please use your firebase config here

const document = {
  someArray: [
    { text: '' },

const converter = {
  toFirestore: (modelObject) => {
    console.log('toFirestore', modelObject)
    modelObject.someArray = 'text'
    return { text: modelObject.someArray[0].text }
  fromFirestore: () => {
    throw new ReferenceError()

// log 'toFirestore' twice, and then fail second conversion.

// log 'toFirestore' only once and complete as expected.
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thebrianchen commented Sep 10, 2020

@hecateball Thanks for filing the bug with an easy repro! We should have a fix for this out in the coming weeks.

@firebase firebase locked and limited conversation to collaborators Oct 12, 2020
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3 participants