Stream does not get updates

[m-sadegh-sh]

I can't get the following stream working. The update command works fine and I can see the changes in the Firestore console, but read is only happening in the first run, and the streaming values does not happen.

Consider the following custom side effect.

extension SideEffectRegistrarExtensions on SideEffectRegistrar {
  CapsuleHandle get use => this as CapsuleHandle;

  Option<DocumentReference<Json>> document({
    required String path,
    required Option<String> id,
  }) {
    final firebaseFirestore = use(firebaseFirestoreCapsule);

    return use.memo(() {
      return id.map((uid) {
        return firebaseFirestore.collection(path).doc(uid);
      });
    }, [path, id]);
  }

  (Option<T>, AsyncSetCallback<T>) readUpdate<T>({
    required Option<DocumentReference<Json>> documentReference,
    required String fieldName,
  }) {
    final getterStream = use.memo(() {
      return documentReference.match(
        (document) {
          return document.snapshots().map((snapshot) {
            if (snapshot.exists) {
              if (snapshot.data()?.containsKey(fieldName) == true) {
                return Maybe.of(snapshot.get(fieldName) as T?);
              }
            }

            return None<T>();
          });
        },
        () {
          return Stream.empty();
        },
      );
    }, [documentReference, fieldName]);

    final getterState = use.stream(getterStream);

    final setterState = use.memo(() {
      return (T newValue) async {
        return await documentReference.match<Future<void>>(
          (document) async {
            await document.set(
              {fieldName: newValue},
              SetOptions(merge: true),
            );
          },
          () async {},
        );
      };
    }, [documentReference, fieldName]);

    return (getterState.data.unwrapOr(None<T>()), setterState);
  }
}

The document should return a reference to a Firestore DocumentReference at a specific path (e.g. /profiles/userid1). Then I will pass that reference to the next one, readUpdate, plus a field name, so I can get/set a specific field of the document.

Option<DocumentReference<Json>> _profileDocumentCapsule(
  CapsuleHandle use,
) {
  final userId = use(userIdCapsule);

  return use.document(
    path: "profiles",
    id: userId.map((id) => id.value),
  );
}

(
  Option<Nickname>,
  AsyncSetCallback<Nickname>,
) _nicknameCapsule(
  CapsuleHandle use,
) {
  final profileDocument = use(_profileDocumentCapsule);

  final (value, setValue) = use.readUpdate<String>(
    documentReference: profileDocument,
    fieldName: 'nickname',
  );

  return (
    Nickname.fromString(value),
    (Nickname newNickname) => setValue(newNickname.value),
  );
}

(
  Option<AgeBracket>,
  AsyncSetCallback<AgeBracket>,
) _ageBracketCapsule(
  CapsuleHandle use,
) {
  final profileDocument = use(_profileDocumentCapsule);

  final (value, setValue) = use.readUpdate<String>(
    documentReference: profileDocument,
    fieldName: 'ageBracket',
  );

  return (
    AgeBracket.fromString(value),
    (AgeBracket newAgeBracket) async {
      await setValue(newAgeBracket.value);
    },
  );
}

Can you help me with this, please?

[m-sadegh-sh]

For an unknown reason, (at least based on my knowledge), this one works fine, both writing changes on Firestore and also getting change streams.

extension SideEffectRegistrarExtensions on SideEffectRegistrar {
  CapsuleHandle get use => this as CapsuleHandle;

  DocumentReference<Json> document({
    required String path,
    required String id,
  }) {
    final firebaseFirestore = use(firebaseFirestoreCapsule);

    return use.memo(() {
      return firebaseFirestore.collection(path).doc(id);
    }, [path, id]);
  }

  (Option<T>, AsyncSetCallback<T>) readUpdate<T>({
    required DocumentReference<Json> document,
    required String fieldName,
  }) {
    final getterStream = use.memo(() {
      return document.snapshots().map((snapshot) {
        if (snapshot.exists) {
          if (snapshot.data()?.containsKey(fieldName) == true) {
            return Maybe.of(snapshot.get(fieldName) as T?);
          }
        }

        return None<T>();
      });
    }, [document, fieldName]);

    final getterState = use.stream(getterStream);

    final setterState = use.memo(() {
      return (T newValue) async {
        await document.set(
          {fieldName: newValue},
          SetOptions(merge: true),
        );
      };
    }, [document, fieldName]);

    return (getterState.data.unwrapOr(None<T>()), setterState);
  }
}

DocumentReference<Json> _profileDocumentCapsule(
  CapsuleHandle use,
) {
  final userId = use(userIdCapsule);

  if (userId case Some(:final value)) {
    return use.document(
      path: "profiles",
      id: value.value,
    );
  }

  throw StateError("No user id found.");
}

(
  Option<Nickname>,
  AsyncSetCallback<Nickname>,
) _nicknameCapsule(
  CapsuleHandle use,
) {
  final profileDocument = use(_profileDocumentCapsule);

  final (value, setValue) = use.readUpdate<String>(
    document: profileDocument,
    fieldName: 'nickname',
  );

  return (
    Nickname.fromString(value),
    (Nickname newNickname) => setValue(newNickname.value),
  );
}

(
  Option<AgeBracket>,
  AsyncSetCallback<AgeBracket>,
) _ageBracketCapsule(
  CapsuleHandle use,
) {
  final profileDocument = use(_profileDocumentCapsule);

  final (value, setValue) = use.readUpdate<String>(
    document: profileDocument,
    fieldName: 'ageBracket',
  );

  return (
    AgeBracket.fromString(value),
    (AgeBracket newAgeBracket) async {
      await setValue(newAgeBracket.value);
    },
  );
}

[m-sadegh-sh]

I just removed the Option in _profileDocumentCapsule ‼️

[GregoryConrad]

Maybe it's something with the Option type you're using then? Maybe just use DocumentReference? instead if you need the optional part.