从 Cloud Firestore Android 检索复杂对象

Question

我正在尝试从Cloud Firestore数据库中检索一组复杂的对象。这是我的课：

public class Book {

    private String id;

    private String name;

    private String original;

    private ArrayList<Author> authors;

    private ArrayList<Translator> translators;

    private Series series;

    private Float no;

    private String seriesNo;

    private Integer published;

    private Borrower borrower;

    private Boolean isCollection;

    private Status status;

}

将此Book对象保存到数据库的最佳方法是什么？我目前正在使用以下方法。

public void createBook(String userId) {

    FirebaseFirestore firebaseFirestore = FirebaseFirestore.getInstance();

    DocumentReference documentReference = firebaseFirestore.collection("books").document();

    Map<String, Object> newBook = new HashMap<>();

    newBook.put("owner", userId);

    newBook.put("id", documentReference.getId());

    newBook.put("name", getName());

    newBook.put("original", getOriginal());

    if (getSeries() != null) {

        Map<String, Object> series = new HashMap<>();

        series.put("id", getSeries().getId());

        series.put("name", getSeries().getName());

        newBook.put("series", series);

    }

    newBook.put("no", getNo());

    newBook.put("seriesNo", getSeriesNo());

    newBook.put("published", getPublished());

    if (getBorrower() != null) {

        Map<String, Object> borrower = new HashMap<>();

        borrower.put("id", getBorrower().getId());

        borrower.put("nameInEnglish", getBorrower().getNameInEnglish());

        borrower.put("nameInSinhalese", getBorrower().getNameInSinhalese());

        borrower.put("mobile", getBorrower().getMobile());

        newBook.put("borrower", borrower);

    }

    newBook.put("isCollection", getIsCollection());

    newBook.put("status", getStatus().toString());

从数据库中检索保存的值的最佳方法是什么？很难找到一种同时访问所有值的好方法。我目前使用以下方法来检索除 Authors 和 Translators（它们是 ArrayLists）之外的值。