fix(firestore): skip ref extraction in non pojo

Fix #1257

src/firestore/utils.ts

@@ -7,7 +7,7 @@ import {
   FirestoreDataConverter,
   Timestamp,
 } from 'firebase/firestore'
-import { isObject, isDocumentRef, TODO } from '../shared'
+import { isObject, isDocumentRef, TODO, isPOJO } from '../shared'
 import { VueFirestoreDocumentData } from '.'
 
 export type FirestoreReference = Query | DocumentReference | CollectionReference
@@ -42,7 +42,7 @@ export function extractRefs(
   oldDoc: DocumentData | void,
   subs: Record<string, { path: string; data: () => DocumentData | null }>
 ): [DocumentData, Record<string, DocumentReference>] {
-  if (!isObject(doc)) return [doc, {}]
+  if (!isPOJO(doc)) return [doc, {}]
 
   const dataAndRefs: [DocumentData, Record<string, DocumentReference>] = [
     {},
@@ -115,6 +115,7 @@ export function extractRefs(
           refs,
         ])
       } else if (isObject(ref)) {
+        // dive into nested refs
         data[key] = {}
         recursiveExtract(ref, oldDoc[key], path + key + '.', [data[key], refs])
       } else {

src/shared.ts

@@ -93,6 +93,16 @@ export function isObject(o: unknown): o is Record<any, unknown> {
   return !!o && typeof o === 'object'
 }
 
+const ObjectPrototype = Object.prototype
+/**
+ *  Check if an object is a plain js object. Differently from `isObject()`, this excludes class instances.
+ *
+ * @param obj - object to check
+ */
+export function isPOJO(obj: unknown): obj is Record<any, unknown> {
+  return isObject(obj) && Object.getPrototypeOf(obj) === ObjectPrototype
+}
+
 /**
  * Checks if a variable is a Firestore Document Reference
  * @param o

tests/firestore/document.spec.ts

@@ -1,14 +1,15 @@
 import { mount } from '@vue/test-utils'
 import { describe, expect, it } from 'vitest'
 import {
+  addDoc,
   doc as originalDoc,
   DocumentData,
   DocumentReference,
   FirestoreError,
 } from 'firebase/firestore'
 import { expectType, setupFirestoreRefs, tds, firestore } from '../utils'
 import { nextTick, ref, shallowRef, unref, type Ref } from 'vue'
-import { _MaybeRef, _Nullable } from '../../src/shared'
+import { isPOJO, _MaybeRef, _Nullable } from '../../src/shared'
 import {
   useDocument,
   VueFirestoreDocumentData,
@@ -147,6 +148,39 @@ describe(
       expect(error.value).toBeUndefined()
     })
 
+    it('can use a custom converter', async () => {
+      class MyName {
+        private _name: string
+        constructor(name: string) {
+          this._name = name
+        }
+
+        get name() {
+          return this._name
+        }
+
+        set name(_newName: string) {
+          // do nothing
+        }
+      }
+      const itemRef = doc().withConverter<MyName>({
+        toFirestore: (data) => ({ name: data.name }),
+        fromFirestore: (snap) => new MyName(snap.get('name')),
+      })
+      await setDoc(itemRef, new MyName('a'))
+
+      const { wrapper, data, promise } = factory({ ref: itemRef })
+
+      await promise.value
+
+      expect(wrapper.vm.item).toHaveProperty('name', 'a')
+      expect(isPOJO(wrapper.vm.item)).toBe(false)
+
+      // should respect the setter
+      wrapper.vm.item!.name = 'b'
+      expect(wrapper.vm.item).toHaveProperty('name', 'a')
+    })
+
     describe('reset option', () => {
       it('resets the value when specified', async () => {
         const { wrapper, itemRef, data } = factory({