com.firebase.client.FirebaseException：无法使用类CLASS_NAME android解析节点 [英] com.firebase.client.FirebaseException: Failed to parse node with class class CLASS_NAME android

问题描述

使用 updateChildren 方法更新Firebase中的现有值时，出现以下异常。

  com.firebase.client.FirebaseException：无法用类类解析节点com.shajeelafzal.quicktasks_app.models.HashTagModel 
 at com.firebase.client.snapshot.NodeUtilities.NodeFromJSON（NodeUtilities.java:84）
 at com.firebase.client.snapshot.NodeUtilities.NodeFromJSON（NodeUtilities.java:12）
 at com .firebase.client.utilities.Validation.parseAndValidateUpdate（Validation.java:127）
 at com.firebase.client.Firebase.updateChildren（Firebase.java:438）
 at com.shajeelafzal.quicktasks_app.fragments .AddEditTaskFragment $ 4.onDataChange（AddEditTaskFragment.java:408）
  

我的模型如下所示：

  public class HashTagModel implements Parcelable {
 $ b $ private HashMap< String，Object> timeStampLastUsed; 
 @Expose 
私人字符串名称; 
 @Expose 
 private String createByUserEmail; 
私人清单< String> tasksKeys; 
 $ b $ public HashTagModel（）{
} 
 
 public HashTagModel（HashMap< String，Object> timeStampLastUsed，String name，
 String createByUserEmail，ArrayList< String> ; tasksKeys）{
 this.timeStampLastUsed = timeStampLastUsed; 
 this.name = name; 
 this.createByUserEmail = createByUserEmail; 
 this.tasksKeys = tasksKeys; 
 
 
 $ / code> 

我想要更新的JSON对象看起来像这样Firebase：

$ p $ hashTags：{
USER_EMAIL：{
USA：{
createByUserEmail：USER_EMAIL，
name：#USA，
tasksKeys：[-K6mS36uhKthKf1-1pF1]，
timeStampLastUsed：{
timestamp：1451514461234
}
}
}
}


我的 onDateChange 方法如下所示：



  public void onDataChange（DataSnapshot dataSnapshot）{
 / **如果哈希标记不存在，则创建一个新的哈希标记。 * / 
 if（dataSnapshot.getValue（）== null）{
 HashMap< String，Object> timestampJoined = new HashMap<>（）; 
 timestampJoined.put（Constants.FIREBASE_PROPERTY_TIMESTAMP，ServerValue.TIMESTAMP）; 
 
 ArrayList< String> keysList = new ArrayList< String>（）; 
 keysList.add（key）; 
 
 HashTagModel hashTag = new HashTagModel（timestampJoined，＃+ mHashTags.get（finalI），
 Utils.decodeEmail（mEncodedEmail），keysList）; 
 finalHashTagLocation.setValue（hashTag）; 
} else {
 
 HashTagModel hashtaghModel = dataSnapshot.getValue（HashTagModel.class）; 
 
 hashtaghModel.getTasksKeys（）。add（key）; 
 $ b $ * / HashMap用于数据更新* / 
 HashMap< String，Object> updateUserTaskData = new HashMap<>（）; 
 
 $ b Utils.updateMapForAllWithValue（null，mHashTags.get（finalI），mEncodedEmail，
 updateUserTaskData，，hashtaghModel，Constants.FIREBASE_LOCATION_USER_HASH_TAGS）; 
 
 $ b / **更新哈希标记* / 
 finalHashTagLocation.updateChildren（updateUserTaskData，new Firebase.CompletionListener（）{
 @Override 
 public void onComplete（firebaseError firebaseError，Firebase firebase）{
 Log.i（，）; 
} 
}）; 
} 
 
 getActivity（）。finish（）; 
 
  




解决方案

code> setValue（）方法， updateChildren（）不会对您的值执行Java到JSON的转换传入。
$ b 您将 HashMap< String，Object> 传递给 updateChildren（），它符合该API的合约。但是我非常肯定你有一个Java对象的值（可能是 HashTagModel ），而这个值并不直接映射到JSON类型。

但是你可以做的是将POJO转换成一个Map：

  Map< String，Object> hashtaghMap = new ObjectMapper（）。convertValue（hashtaghModel，Map.class）;然后你可以把值的映射到你传入的值中$ c $ $ 
 
 
 
 
 $ p $ c> updateChildren（）。
 
I am getting following exception while updating an existing value in the Firebase using updateChildren method. 
com.firebase.client.FirebaseException: Failed to parse node with class class com.shajeelafzal.quicktasks_app.models.HashTagModel
  at com.firebase.client.snapshot.NodeUtilities.NodeFromJSON(NodeUtilities.java:84)
  at com.firebase.client.snapshot.NodeUtilities.NodeFromJSON(NodeUtilities.java:12)
  at com.firebase.client.utilities.Validation.parseAndValidateUpdate(Validation.java:127)
  at com.firebase.client.Firebase.updateChildren(Firebase.java:438)
  at com.shajeelafzal.quicktasks_app.fragments.AddEditTaskFragment$4.onDataChange(AddEditTaskFragment.java:408)
My model looks like this:
public class HashTagModel implements Parcelable {

    private HashMap<String, Object> timeStampLastUsed;
    @Expose
    private String name;
    @Expose
    private String createByUserEmail;
    private List<String> tasksKeys;

    public HashTagModel() {
    }

    public HashTagModel(HashMap<String, Object> timeStampLastUsed, String name,
                        String createByUserEmail, ArrayList<String> tasksKeys) {
        this.timeStampLastUsed = timeStampLastUsed;
        this.name = name;
        this.createByUserEmail = createByUserEmail;
        this.tasksKeys = tasksKeys;
    }
}
JSON Object that I want to update looks like this on Firebase:
"hashTags" : {
    "USER_EMAIL" : {
      "USA" : {
        "createByUserEmail" : "USER_EMAIL",
        "name" : "#USA",
        "tasksKeys" : [ "-K6mS36uhKthKf1-1pF1" ],
        "timeStampLastUsed" : {
          "timestamp" : 1451514461234
        }
      }
    }
  }
And my onDateChange method looks like this:
public void onDataChange(DataSnapshot dataSnapshot) {
    /** if the hash tag does not exists already then create new one. */
    if (dataSnapshot.getValue() == null) {
        HashMap<String, Object> timestampJoined = new HashMap<>();
        timestampJoined.put(Constants.FIREBASE_PROPERTY_TIMESTAMP, ServerValue.TIMESTAMP);

        ArrayList<String> keysList = new ArrayList<String>();
        keysList.add(key);

        HashTagModel hashTag = new HashTagModel(timestampJoined, "#" + mHashTags.get(finalI),
                Utils.decodeEmail(mEncodedEmail), keysList);
        finalHashTagLocation.setValue(hashTag);
    } else {

        HashTagModel hashtaghModel = dataSnapshot.getValue(HashTagModel.class);

        hashtaghModel.getTasksKeys().add(key);

        /* HashMap for data to update */
        HashMap<String, Object> updateUserTaskData = new HashMap<>();


        Utils.updateMapForAllWithValue(null, mHashTags.get(finalI), mEncodedEmail,
                updateUserTaskData, "", hashtaghModel, Constants.FIREBASE_LOCATION_USER_HASH_TAGS);


        /** update the Hash Tag */
        finalHashTagLocation.updateChildren(updateUserTaskData, new Firebase.CompletionListener() {
            @Override
            public void onComplete(FirebaseError firebaseError, Firebase firebase) {
                Log.i("", "");
            }
        });
    }

    getActivity().finish();
}

解决方案
Unlike the setValue() method, updateChildren() does not perform a Java-to-JSON conversion on the value(s) you pass in.

You're passing a HashMap<String, Object> into updateChildren(), which fits the contract of that API. But I'm pretty sure in some of the values you have a Java object (likely a HashTagModel) that is not directly mapped to a JSON type. 

But what you can do is convert the POJO into a Map with:
Map<String, Object> hashtaghMap = new ObjectMapper().convertValue(hashtaghModel, Map.class);
Then you can put the map of values into the values that you're passing into updateChildren().

                        
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