java - 从 Firestore 增加值(value)

Question

我的条目如下所示:

在输入数据之前，必须使用条码扫描仪填写条码。当 Firestore 中存在条形码时，我希望增加产品数量。当条形码在 Firestore 中不可用时，Intent 到另一个类。

代码:

@Override
public void handleResult(Result result) {
    final String scanResult = result.getText();

    ToneGenerator toneNotification = new ToneGenerator(AudioManager.STREAM_NOTIFICATION, 100);
    toneNotification.startTone(ToneGenerator.TONE_PROP_BEEP, 150);

    collectionReference.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
        @Override
        public void onComplete(@NonNull Task<QuerySnapshot> task) {
            if (task.isSuccessful()) {
                for (QueryDocumentSnapshot queryDocumentSnapshot : task.getResult()) {
                    // if barcode is existing, then product quantity to increment
                    if (queryDocumentSnapshot.getString("barCode") != null) {
                        collectionReference.document(queryDocumentSnapshot.getId()).update("productQuantity", FieldValue.increment(1));
                        Intent moveView = new Intent(ScannersActivity.this, ViewData.class);
                        moveView.putExtra("documentID", documentID);
                        startActivity(moveView);
                        finish();
                    } else { // If barcode is not available in firestore, then intent to another class
                        Intent moveCode = new Intent(ScannersActivity.this, AddItems.class);
                        moveCode.putExtra("sendDocumentID", documentID);
                        moveCode.putExtra("ScanResult", scanResult);
                        startActivity(moveCode);
                        finish();
                    }
                }
            }
        }
    });
}

Answer 1

要根据 barCode 属性的存在来增加 productQuantity 属性的值，请尝试以下代码行:

collectionReference.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (QueryDocumentSnapshot document : task.getResult()) {
                if (document.getString("barCode") != null) {
                    collectionReference.document(document.getId()).update(
                        "productQuantity", FieldValue.increment(1)
                    );
                }
            }
        }
    }
});