Google Play分发应用Firestore指定字段返回空值，本地调试正常

我的应用目前仅在Google Play内部测试轨道发布，通过Android Studio启动运行无异常，但上传至Google Play后，卸载手机上的版本再下载安装，启动时执行以下代码中document.get("Best level")、document.get("Best number of words")、document.get("Best word length")和document.get("Play sounds")均返回null。

private static final String FSBESTLEVEL = "Best level";
private static final String FSBESTNUMWORDS = "Best number of words";
private static final String FSBESTWORDLEN = "Best word length";
private static final String FSSOUNDS = "Play sounds";


private void getSettings() {
    spinner.setVisibility(View.VISIBLE);
    mDevIDDocRef.get().addOnCompleteListener(new 
OnCompleteListener<DocumentSnapshot>() {
//        mDevIDDocRef.get(Source.SERVER).addOnCompleteListener(new 
OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            DocumentSnapshot document = task.getResult();
            assert document != null;
            if (document.exists()) {
                // Handle the legacy Best score field, which was a String.
                // All the documents that contained a non-blank score have
                // already been converted to Long.
                if (document.get(FSBESTSCORE) instanceof String) {
                    updateFieldType(BEGINNER_TIME/1000L);
                    myScore = BEGINNER_TIME/1000;
                } else {
                    myScore = (Long)document.get(FSBESTSCORE);
                }
                level_val = ((Long) Objects.requireNonNull(document.get(FSLEVEL))).intValue();
                if (document.get(FSBESTLEVEL) == null) {
                    best_level_val = 0;
                    updateBestLevel(level_val);
                } else {
                    best_level_val = ((Long)document.get(FSBESTLEVEL)).intValue();
                }
                num_words_val = ((Long) Objects.requireNonNull(document.get(FSNUMWORDS))).intValue();
                if (document.get(FSBESTNUMWORDS) == null) {
                    best_num_words_val = 0;
                    updateBestNumwords(num_words_val);
                } else {
                    best_num_words_val = ((Long)document.get(FSBESTNUMWORDS)).intValue();
                }
                if (document.get(FSBESTWORDLEN) == null) {
                    best_word_length_val = 0;
                    updateBestWordLength(best_word_length_val);
                } else {
                    best_word_length_val = ((Long)document.get(FSBESTWORDLEN)).intValue();
                }
                word_length_val = ((Long) Objects.requireNonNull(document.get(FSWORDLEN))).intValue();
                order_important_val = (boolean) document.get(FSORDER);
                if (document.get(FSSOUNDS) == null) {
                    play_sounds_val = true;
                    updatePlaySounds(play_sounds_val);
                } else {
                    play_sounds_val = (boolean) document.get(FSSOUNDS);
                }
                uname = (String) document.get(FSUSERNAME);
                button_continue.setEnabled(true);
                // If the user name hasn't been set, show the prompt and don't let the user
                // go to the next page until they've entered one.
                if (uname == null || uname.length() == 0) {
                    no_screen_name = true;
                    screen_name_prompt.setVisibility(View.VISIBLE);
                    screen_name_fld.setVisibility(View.VISIBLE);
                } else {
                    no_screen_name = false;
                    screen_name_prompt.setVisibility(View.INVISIBLE);
                    screen_name_fld.setVisibility(View.INVISIBLE);
                }
                savePrefs(myScore, level_val, best_level_val, num_words_val, best_num_words_val, word_length_val, best_word_length_val, order_important_val, play_sounds_val, androidID, uname);
                spinner.setVisibility(View.INVISIBLE);
            } else {
                createUserDocument();
            }
        } else {
            Log.e(TAG, "getSettings() error" + task.getException());
            Toast.makeText(context, "getSettings() error" + task.getException(), Toast.LENGTH_LONG).show();
            crashlytics.log(Objects.requireNonNull(Objects.requireNonNull(task.getException()).getMessage()));
            level_val = sharedPref.getInt(FSLEVEL, 0);
            num_words_val = sharedPref.getInt(FSNUMWORDS, 0);
            word_length_val = sharedPref.getInt(FSWORDLEN, 0);
            order_important_val = sharedPref.getBoolean(FSORDER, false);
            play_sounds_val = sharedPref.getBoolean(FSSOUNDS, true);
            spinner.setVisibility(View.INVISIBLE);
        }
    }
});
}

1. 补全用户文档初始化逻辑 #

核心问题大概率是createUserDocument()创建新用户文档时，未初始化FSBESTLEVEL、FSBESTNUMWORDS、FSBESTWORDLEN、FSSOUNDS这些字段。调试时你可能已有包含这些字段的测试文档，所以读取正常；但Google Play新用户首次启动时，文档是全新创建的，缺少字段导致get()返回null。

修改createUserDocument()，添加默认值初始化：

Map<String, Object> userData = new HashMap<>();
userData.put(FSBESTLEVEL, 0);
userData.put(FSBESTNUMWORDS, 0);
userData.put(FSBESTWORDLEN, 0);
userData.put(FSSOUNDS, true);
// 其他必要字段初始化...
mDevIDDocRef.set(userData);

2. 强制从服务器拉取数据 #

当前代码注释掉了Source.SERVER参数，默认会优先读取本地缓存（若存在）。恢复该参数可避免潜在的缓存同步问题，确保每次都从服务器获取最新文档：

mDevIDDocRef.get(Source.SERVER).addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {

3. 优化字段读取的健壮性 #

使用Firebase提供的类型安全方法读取字段，直接设置默认值，减少冗余的null判断：

best_level_val = document.getLong(FSBESTLEVEL) != null ? document.getLong(FSBESTLEVEL).intValue() : 0;
best_num_words_val = document.getLong(FSBESTNUMWORDS) != null ? document.getLong(FSBESTNUMWORDS).intValue() : 0;
best_word_length_val = document.getLong(FSBESTWORDLEN) != null ? document.getLong(FSBESTWORDLEN).intValue() : 0;
play_sounds_val = document.getBoolean(FSSOUNDS) != null ? document.getBoolean(FSSOUNDS) : true;

4. 验证Firebase安全规则 #

确认Firebase数据库规则允许发布版本的应用读取用户文档。调试签名和发布签名的SHA-1不同，需确保两者都添加到Firebase项目的应用设置中，避免权限拦截。

内容的提问来源于stack exchange，提问作者FractalBob