与领域的Firebase。反序列化POJO类 [英] Firebase with Realm. De-serializing POJO class

问题描述

错误：参数1的类型为io。我的firebase数据库中有数据，一切正常，直到我尝试反序列化数据。 realm.RealmList，得到java.util.ArrayList

这里是我的代码：

  DatabaseReference root = FirebaseDatabase.getInstance（）。 
 getReferenceFromUrl（https://swing-8792d.firebaseio.com/playlist）; 
查询playlistQuery = root.orderByKey（）。equalTo（key）; 
 playlistQuery.addListenerForSingleValueEvent（new ValueEventListener（）{
 @Override $ b $ public void onDataChange（DataSnapshot dataSnapshot）{
 for（DataSnapshot child：dataSnapshot.getChildren（））{
 
 Log.d（Child，child +）; 
 
 Playlist receivedPlaylist = child.getValue（Playlist.class）; 
 Playlist playlist = new Playlist ; 
 
 playlist.setCreatedBy（receivedPlaylist.getCreatedBy（））; 
 playlist.setName（receivedPlaylist.getName（））; 
 playlist.setMyMap（receivedPlaylist.getMyMap（））; 
 playlist.setQrKey（receivedPlaylist.getQrKey（））; 
 playlist.setCount（receivedPlaylist.getCount（））; 
 playlist.setId（receivedPlaylist.getId（））; 
 playlist .setTracks（receivedPlaylist.getTracks（））; 
 mPlaylist.add（播放列表）; 
 
 
 
 $ b 
这是我的POJO类：
 
 
  @RealmClass 
 public class Playlist extends RealmObject {
 
 String name; 
长ID; 
 RealmList< Track>轨道; 
整数; 
字符串createdBy; 
 RealmList< UserMap> MYMAP; 
字符串qrKey; 
 
 public RealmList< UserMap> getMyMap（）{
返回myMap; 
 
 $ b $ public void setMyMap（RealmList< UserMap> myMap）{
 this.myMap = myMap; 
 
 $ b $ public播放列表（）{} 
 
 
 $ b public String getQrKey（）{
 return qrKey; 
} 
 
 public void setQrKey（String qrKey）{
 this.qrKey = qrKey; 
} 
 
 public String getCreatedBy（）{
 return createdBy; 
} 
 
 public void setCreatedBy（String createdBy）{
 this.createdBy = createdBy; 
} 
 
 
 public RealmList< Track> getTracks（）{
返回曲目; 
 
 
 public void setTracks（RealmList< Track> tracks）{
 this.tracks = tracks; 
} 
 
 public String getName（）{
 return name; 
} 
 
 public void setName（String name）{
 this.name = name; 
} 
 
 public Long getId（）{
 return id; 
} 
 
 public void setId（Long id）{
 this.id = id; 
} 
 
 public Integer getCount（）{
 return count; 
} 
 
 public void setCount（Integer count）{
 this.count = count; 
 
 code 
 
 
 
 
 
 
 
 
 
 
 $ b $ p 
 
 
 $ b 
如果我尝试使用普通的POJO类（即移除领域）进行反序列化，它就可以正常工作。    解决方案

Firebase不起作用类没有默认构造函数或私有变量，即没有公共getter / setter。



更简单的解决方案你的情况将是一个中间件类是相同的pojo只是没有扩展RealmObject。接下来使用pojo的值初始化你的RealmObject子类。



伪代码



  class SimplePojoPlaylist {
 public String变量; 
} 
 
类播放列表扩展RealmObject {
 public String variable;然后先投入 SimplePojoPlaylist  $ b  

（DataSnapshot child：dataSnapshot.getChildren（））{
SimplePojoPlaylist receivedPlaylist = child.getValue（SimplePojoPlaylist（））;}
$ b

 。类）; 
 Playlist playList = new Playlist（）; 
 playList.variable = receivedPlaylist.variable; 
} 
  




I have data in my firebase DB, everything works fine until I try to De-serialize the data.

Error: argument 1 has type io.realm.RealmList, got java.util.ArrayList

Here's my code:

 DatabaseReference root = FirebaseDatabase.getInstance().
                getReferenceFromUrl("https://swing-8792d.firebaseio.com/playlist");
        Query playlistQuery = root.orderByKey().equalTo(key);
        playlistQuery.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for (DataSnapshot child : dataSnapshot.getChildren()) {

                    Log.d("Child", child + "");

                    Playlist receivedPlaylist = child.getValue(Playlist.class);
                    Playlist playlist = new Playlist();

                    playlist.setCreatedBy(receivedPlaylist.getCreatedBy());
                    playlist.setName(receivedPlaylist.getName());
                    playlist.setMyMap(receivedPlaylist.getMyMap());
                    playlist.setQrKey(receivedPlaylist.getQrKey());
                    playlist.setCount(receivedPlaylist.getCount());
                    playlist.setId(receivedPlaylist.getId());
                    playlist.setTracks(receivedPlaylist.getTracks());
                    mPlaylist.add(playlist);
 }

This is my POJO class:

@RealmClass
public class Playlist extends RealmObject {

String name;
Long id;
RealmList<Track> tracks;
Integer count;
String createdBy;
RealmList<UserMap> myMap;
String qrKey;

public RealmList<UserMap> getMyMap() {
    return myMap;
}

public void setMyMap(RealmList<UserMap> myMap) {
    this.myMap = myMap;
}

public Playlist(){}



public String getQrKey() {
    return qrKey;
}

public void setQrKey(String qrKey) {
    this.qrKey = qrKey;
}

public String getCreatedBy() {
    return createdBy;
}

public void setCreatedBy(String createdBy) {
    this.createdBy = createdBy;
}


public RealmList<Track> getTracks() {
    return tracks;
}

public void setTracks(RealmList<Track> tracks) {
    this.tracks = tracks;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public Integer getCount() {
    return count;
}

public void setCount(Integer count) {
    this.count = count;
}

}

If I try to de-serialize with Normal POJO class (i.e Removing Realm) it works fine.

解决方案

Firebase won't work with classes that do not have default constructor or private variables i.e no public getter/setter.

A easier solution in your case would be to make a middleware class that is the same pojo just not extending RealmObject. Next initialise your RealmObject subclass using the values of the pojo.

Pseudo code

class SimplePojoPlaylist  {
     public String variable;
}

class Playlist extends RealmObject {
     public String variable;
}

Then first cast into SimplePojoPlaylist

    for (DataSnapshot child : dataSnapshot.getChildren()) {
         SimplePojoPlaylist receivedPlaylist = child.getValue(SimplePojoPlaylist.class);
         Playlist playList = new Playlist();
         playList.variable = receivedPlaylist.variable;
    }

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