如何捕获java.lang.RuntimeException:无法从Firebase ClassMapper反序列化对象并添加默认值 [英] How to catch java.lang.RuntimeException: Could not deserialize object from Firebase ClassMapper and add default Values

问题描述

我正在使用Firebase UI回收适配器从Firestore读取数据

I am using Firebase UI Recycler Adapter to read data from Firestore

FirestoreRecyclerOptions<Transaction> options =
                new FirestoreRecyclerOptions.Builder<Transaction>()
                        .setQuery(mQuery, Transaction.class)
                        .setLifecycleOwner(this)
                        .build();

        mAdapter = new TransactionAdapter(options, this, getActivity()) {

            @Override
            public void onDataChanged() {
                // Show/hide content if the query returns empty.
                if (getItemCount() == 0) {
                    mRestaurantsRecycler.setVisibility(View.GONE);
                    mEmptyView.setVisibility(View.VISIBLE);
                } else {
                    mRestaurantsRecycler.setVisibility(View.VISIBLE);
                    mEmptyView.setVisibility(View.GONE);
                }
            }

            @Override
            public void onError(FirebaseFirestoreException e) {
                Log.e("Error", ", not initializing RecyclerView",e);
            }
        };
        Log.w("Test", "No6 query, not initializing RecyclerView");
        mRestaurantsRecycler.setLayoutManager(new LinearLayoutManager(getActivity()));
        mRestaurantsRecycler.setAdapter(mAdapter);

对于Firestore中某些损坏的字段，我的状态已变得异常

i am getting below exception for some corrupted fields in Firestore

java.lang.RuntimeException: Could not deserialize object. Failed to convert a value of type java.lang.String to double (found in field 'amount')
    at com.google.firebase.firestore.util.CustomClassMapper.deserializeError(com.google.firebase:firebase-firestore@@17.1.4:524)
    at com.google.firebase.firestore.util.CustomClassMapper.convertDouble(com.google.firebase:firebase-firestore@@17.1.4:427)
    at com.google.firebase.firestore.util.CustomClassMapper.deserializeToPrimitive(com.google.firebase:firebase-firestore@@17.1.4:304)
    at com.google.firebase.firestore.util.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-firestore@@17.1.4:215)
    at com.google.firebase.firestore.util.CustomClassMapper.deserializeToType(com.google.firebase:firebase-firestore@@17.1.4:180)
    at com.google.firebase.firestore.util.CustomClassMapper.access$200(com.google.firebase:firebase-firestore@@17.1.4:53)
    at com.google.firebase.firestore.util.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-firestore@@17.1.4:700)
    at com.google.firebase.firestore.util.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-firestore@@17.1.4:674)
    at com.google.firebase.firestore.util.CustomClassMapper.convertBean(com.google.firebase:firebase-firestore@@17.1.4:503)
    at com.google.firebase.firestore.util.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-firestore@@17.1.4:242)
    at com.google.firebase.firestore.util.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-firestore@@17.1.4:97)
    at com.google.firebase.firestore.DocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.4:203)
    at com.google.firebase.firestore.QueryDocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.4:121)
    at com.google.firebase.firestore.DocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.4:183)
    at com.google.firebase.firestore.QueryDocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.4:101)
    at com.firebase.ui.firestore.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:23)
    at com.firebase.ui.firestore.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:12)
    at com.firebase.ui.common.BaseCachingSnapshotParser.parseSnapshot(BaseCachingSnapshotParser.java:35)
    at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
    at com.firebase.ui.firestore.FirestoreRecyclerAdapter.getItem(FirestoreRecyclerAdapter.java:83)
    at com.firebase.ui.firestore.FirestoreRecyclerAdapter.onBindViewHolder(FirestoreRecyclerAdapter.java:125)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5913)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
    at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:3225)
    at android.view.View.measure(View.java:22071)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
    at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:739)

我知道为什么会引发此错误，并且我也知道如果我在Firestore数据库中更正我的金额字段或通过使用Cloud Function来检查数据验证等，就可以更正此错误.

I know why this error is thrown and i also know i can correct this if i correct my amount field in Firestore Database or by having a Cloud Function to check data validation etc.

但是我不希望有App崩溃的经历.是否有任何方法可以捕获并添加任何默认值或为损坏的值添加Null.显示单个Null或NA字段或整个空白屏幕总是比Crash更好.

But I don't want an App crash experience. Is there any way to catch and add any default value or Null for corrupted values. Showing an individual Null or NA field or an entire empty screen is always better than a Crash.

为了设置默认值并避免运行时异常，我在Model类中尝试了此操作.我仍然不知道是否有办法捕获此异常.

In order to set a default value and avoid Runtime exception i have tried this with my Model class. I still don't know if there is a way to catch this exception.

public double amount;
public double getAmount() {
    return amount;
}
// If you change it Object, ClassMapper will not throw any exception and 
// You can parse any data type by yourself and also set a default value.
public void setAmount(Object amount) {
    try {
        // You can also add  instanceOf check
        this.amount = Double.parseDouble(amount.toString());
    } catch (Exception e) {
        // Set your default value
        this.amount = 0.00;
    }
}

推荐答案

在您从

I'm answering this question becase of your request from here. So because I see that you are using the Firebase-UI library, there is no need to use a try-catch block. As also @FrankvanPuffelen mentioned in his comment, the simplest thing that you can do, is to override the onError method in your adapter class like this:

FirestoreRecyclerAdapter adapter = new FirestoreRecyclerAdapter<Chat, ChatHolder>(options) {
    @Override
    public void onDataChanged() {
        //Called each time there is a new query snapshot.
    }

    @Override
    public void onError(FirebaseFirestoreException e) {
        //Handle the error
        Log.d(TAG, e.getMessage());
    }
};

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