Firestore: CollectionReference.withConverter(converter).add(data) invokes converter.toFirestore twice #3742
Description
[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
firebase.initializeApp(firebaseConfig)
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.
firebase.firestore().collection('posts')
.withConverter(converter)
.add(document)
// log 'toFirestore' only once and complete as expected.
firebase.firestore().collection('posts')
.withConverter(converter)
.doc()
.set(document)