fix(firestore): track all ref subs

fix #1223

src/firestore/utils.ts

@@ -87,18 +87,18 @@ export function extractRefs(
       ) {
         data[key] = ref
       } else if (isDocumentRef(ref)) {
+        // key for the subscription
+        const refSubKey = path + key
         // allow values to be null (like non-existent refs)
         // TODO: better typing since this isObject shouldn't be necessary but it doesn't work
         data[key] =
-          typeof oldDoc === 'object' &&
-          key in oldDoc &&
-          // only copy refs if they were refs before
+          // if the ref was already bound, keep the same object
+          // otherwise set the path as a string so it can be bound later
           // https://github.com/vuejs/vuefire/issues/831
-          typeof oldDoc[key] != 'string'
-            ? oldDoc[key]
-            : ref.path
+          // https://github.com/vuejs/vuefire/pull/1223
+          refSubKey in subs ? oldDoc[key] : ref.path
         // TODO: handle subpathes?
-        refs[path + key] = ref
+        refs[refSubKey] = ref
       } else if (Array.isArray(ref)) {
         data[key] = Array(ref.length)
         // fill existing refs into data but leave the rest empty

tests/firestore/refs-in-documents.spec.ts

@@ -156,6 +156,37 @@ describe('Firestore refs in documents', async () => {
     expect(data.value).toEqual({ a: aRef.path })
   })
 
+  // https://github.com/vuejs/vuefire/pull/1223
+  it('sets the path even if the value was null before', async () => {
+    const docRef = await addDoc(listOfRefs, { a: null })
+    const { data, pending, promise } = factory({
+      ref: docRef,
+      options: { maxRefDepth: 0 },
+    })
+
+    await promise.value
+    expect(data.value).toEqual({ a: null })
+    await updateDoc(docRef, { a: aRef })
+    expect(data.value).toEqual({ a: aRef.path })
+  })
+
+  it('keeps null for non existent docs refs when updating the doc', async () => {
+    const docRef = await addDoc(listOfRefs, { a: null })
+
+    const { data, promise } = factory({ ref: docRef })
+    await promise.value
+
+    expect(data.value).toEqual({ a: null })
+
+    await updateDoc(docRef, { a: emptyRef })
+
+    expect(data.value).toEqual({ a: null })
+
+    await updateDoc(docRef, { name: 'd' })
+
+    expect(data.value).toEqual({ a: null, name: 'd' })
+  })
+
   it('does not fail with cyclic refs', async () => {
     const docRef = await addDoc(listOfRefs, {})
     await setDoc(docRef, { ref: docRef })