Question

I'm working with a application that used Firebase as data repository. I'm just refactor whole my app to implement Clean Architecture and RxJava. Doing everything in this way I found a problem managing my model objects.

Here is my problem: I have a Post.class with the same fields and values that I can retrieve from Firebase database reference:

 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;
}

Everything fine for now. My problem appear when I retrieve the data from my Observer in my repository class:

@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);
}

With this observer I already manage all the listeners and data calls, my only problem is these lines:

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

I think that is not a good practice to set the reference as a new field in the Post Model which should equal to my firebase Json Tree. So my question is: Is a good practice to create 2 different models? One like "dbPost" and "PostEntity". One with the firebase values and the other one with a builder from a dbPost and the new fields that I want to save(dbReference and maybe valueListener)?

Answer 1

最后我做的是创建两个不同的模型类。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，用于管理具有应用程序所需的额外值的数据：

应用型号：

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
}
[......]

Firebase型号：

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注释可用于排除某些字段更新为firebase，因此您可以使用这些排除字段来存储您自己的数据，例如post.ref

我的应用中的示例：

＆＃13;

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;

＆＃13;

Multiple Model Classes for same firebase element

2 个答案: