同一firebase元素的多个模型类

Question

我正在使用一个使用Firebase作为数据存储库的应用程序。我只是重构了整个应用来实现Clean Architecture和RxJava。以这种方式做所有事情，我发现管理我的模型对象有问题。

这是我的问题:我有一个Post.class具有相同的字段和值，我可以从Firebase数据库引用检索:

 public Post(Author author, String full_url, String full_storage_uri, String thumb_url, String thumb_storage_uri, String text, Object timestamp) {
    this.author = author;
    this.full_url = full_url;
    this.text = text;
    this.timestamp = timestamp;
    this.thumb_storage_uri = thumb_storage_uri;
    this.thumb_url = thumb_url;
    this.full_storage_uri = full_storage_uri;
}

现在一切都好。当我从存储库类中的Observer中检索数据时，问题就出现了:

@Override
public Observable<List<Post>> getPosts(final String groupId){
    return Observable.fromAsync(new Action1<AsyncEmitter<List<Post>>>() {
        @Override
        public void call(final AsyncEmitter<List<Post>> listAsyncEmitter) {
            final ValueEventListener PostListener = new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot snapshot) {
                    final List<Post> postList = new ArrayList<>();
                    Log.e("Count ", "" + snapshot.getChildrenCount());
                    //For every child, create a Post object
                    for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                        Post post = postSnapshot.getValue(Post.class);
                        Log.e("new post added ", postSnapshot.getKey());
                        //Set the databaseReference to the object, which is needed later
                        post.setRef(postSnapshot.getKey());
                        postList.add(post);
                    }
                    listAsyncEmitter.onNext(postList);
                }
                @Override
                public void onCancelled(DatabaseError databaseError) {
                    Log.e("The read failed: ", databaseError.getMessage());
                }
            };
            //Remove listener when unsuscribe
            listAsyncEmitter.setCancellation(new AsyncEmitter.Cancellable() {
                @Override
                public void cancel() throws Exception {
                    getPostsRef().child(groupId).removeEventListener(PostListener);
                }
            });
            //Set the listener 
            getPostsRef().child(groupId).addValueEventListener(PostListener);
        }
    }, AsyncEmitter.BackpressureMode.BUFFER);
}

有了这个观察者，我已经管理了所有的侦听器和数据调用，我唯一的问题是这几行:

  //Set the databaseReference to the object, which is needed later
  post.setRef(postSnapshot.getKey());

我认为将引用设置为Post模型中的新字段不是个好做法，它应该等于我的firebase Json树。所以我的问题是:创建两个不同的模型是一个好的做法吗?比如"dbPost"one_answers"PostEntity"。一个具有firebase值，另一个具有来自dbPost的构建器和我想要保存的新字段(dbReference和valuellistener)?

Answer 1

最后我创建了两个不同的模型类。其中一个用于从Firebase检索和插入我的数据库参数，另一个用于我的应用程序管理数据，它需要考虑应用程序的额外值:

应用模型:

public class Post implements Parcelable{
private Author author;
private String full_url;
private String thumb_storage_uri;
private String thumb_url;
private String text;
private Object timestamp;
private String full_storage_uri;
private String ref;
private Achivement post_achivement;
private long post_puntuation;
public Post() {
    // empty default constructor, necessary for Firebase to be able to deserialize blog posts
}
[......]

重火力点模型:

public class NetworkPost {
private Author author;
private String full_url;
private String thumb_storage_uri;
private String thumb_url;
private String text;
private Object timestamp;
private String full_storage_uri;
private Achivement post_achivement;
private long post_puntuation;
public NetworkPost() {
    // empty default constructor, necessary for Firebase to be able to deserialize blog posts
}

[…]

Answer 2

@Exclude注释可用于在更新到firebase时排除某些字段，因此您可以使用这些被排除的字段来存储您自己的数据，如post.ref

在我的应用程序中的例子:

class LocationRecord {
    public final Integer id;
    public final String title;
    public final String address;
    public final Double latitude;
    public final Double longitude;
    @Exclude
    public Integer distance;