How to get favourite data from firestore using flutter

I have created the below method that make the item favourite as favourite like the below one:

  void petFavorite(String petId) {
    FirebaseFirestore.instance
        .collection('pets')
        .doc(petId)
        .collection('favorites')
        .doc(userModel.uId)
        .set({
      'favorite': true,
    }).then((value) {
      emit(AppGetFavoritesSuccessState());
    }).catchError((error) {
      emit(AppGetFavoritesErrorState(error.toString()));
    });
  }

and this the below method which gets all the data in the fire Store:

List<String> petsId = [];
List<PetsModel> pets = [];

  void getPetsData() {
    FirebaseFirestore.instance.collection('pets').get().then((value) {
      value.docs.forEach((element) {
        petsId.add(element.id);
        pets.add(PetsModel.fromJson(element.data()));
      });
      emit(AppGetPetsSuccessState());
    }).catchError((error) {
      emit(AppGetPetsErrorState(error.toString()));
    });
  }

and this is the below models.. Pet Model:

class PetsModel {
  String image;
  String name;
  String gender;
  String age;
  String petType;
  String price;
  String type;
  String distance;

  PetsModel({
    this.image,
    this.name,
    this.gender,
    this.petType,
    this.price,
    this.age,
    this.type,
    this.distance,
  });

  PetsModel.fromJson(Map<String, dynamic> map) {
    image = map['image'];
    name = map['name'];
    gender = map['gender'];
    age = map['age'];
    petType = map['animal_type'];
    price = map['price'];
    type = map['type'];
    distance = map['distance'];
  }

  Map<String, dynamic> toMap() {
    return {
      'name': name,
      'image': image,
      'gender': gender,
      'animal_type': petType,
      'age': age,
      'price': price,
      'type': type,
      'distance': distance,
    };
  }
}

user model:

class UserModel {
  String name;
  String email;
  String phone;
  String uId;
  String image;
  String cover;
  String bio;
  bool isEmailVerified;

  UserModel({
    this.name,
    this.email,
    this.phone,
    this.uId,
    this.image,
    this.cover,
    this.bio,
    this.isEmailVerified,
  });

  UserModel.fromJson(Map<String, dynamic> json) {
    email = json['email'];
    name = json['name'];
    phone = json['phone'];
    uId = json['uId'];
    image = json['image'];
    cover = json['cover'];
    bio = json['bio'];
    isEmailVerified = json['isEmailVerified'];
  }

  Map<String, dynamic> toMap() {
    return {
      'name': name,
      'email': email,
      'phone': phone,
      'uId': uId,
      'image': image,
      'cover': cover,
      'bio': bio,
      'isEmailVerified': isEmailVerified,
    };
  }
}

I tried the below code but it brings all pets:

  List<PetsModel> favoritePets = [];
  void getFavoritePets() {
    emit(AppGetFavoritePetsLoadingState());
    FirebaseFirestore.instance.collection('pets').get().then((value) {
      value.docs.forEach((element) {
        element.reference.collection('favorites').where('favorite', isEqualTo: true).get().then((value) {
          favoritePets.add(PetsModel.fromJson(element.data()));
        });
      });
    });
  }

and this method get the userData:

UserModel userModel;
  getUserData() {
    emit(AppGetUserLoadingState());
    FirebaseFirestore.instance.collection('users').doc(uId).get().then((value) {
      userModel = UserModel.fromJson(value.data());
      emit(AppGetUserSuccessState());
    }).catchError((error) {
      print(error.toString());
      emit(AppGetUserErrorState(error.toString()));
    });
  }

I need only the favourite pets for every own user..

Is this the right logic I am working on? or I have to save this favourites collection in every users instead every pet?

so now I want to create a method that gets the favourites from the below collection as it looks like the below image:

and this is the below user data: