Android Firebase更新现有值，而不是setValue来创建新记录 [英] Android Firebase update existing value instead of setValue creating a new record

问题描述

我的Android应用上有一个按钮，当按下该按钮时，它将更新Firebase数据库中的分数；

I have a button on my Android app that when pressed should update the score in the Firebase database;

            // UPDATE DATABASE START
            final String getArgument = getArguments().getString("matchid");
            DatabaseReference database = FirebaseDatabase.getInstance().getReference();
            final DatabaseReference ref = database.child("Matches");
            final Query gameQuery = ref.orderByChild("gameID").equalTo(getArgument);

            gameQuery.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot snapshot) {
                    if(snapshot.exists()){
                        for (DataSnapshot child: snapshot.getChildren()) {
                            ref.child(getArgument).child("homeScore").setValue(5);
                        }
                    }
                }
                @Override
                public void onCancelled(DatabaseError databaseError) {
                }
            });
            //UPDATE DATABASE END

执行代码时，我在数据库中获得了一条新记录，而不是更新现有字段数据.我通过Firebase控制台手动启动了数据库，而不是通过编程方式更新记录，因此我使用在数据库中作为PK创建的gameID. 我已经将该值硬编码为要更新为5的值，以使其首先起作用.

When I execute the code I get a new record in the database instead of updating the existing fields data. I've hand cranked the database through the Firebase console instead of programmatically updating the records, so I use gameID that I created as my PK in the DB. I've hard coded the value to be updated to 5 to get it working first.

Firebase中的数据结构是;

The data structure in Firebase is;

-Matches
 - Match_01
  -matchID
  -homeScore
  -etc....

感谢所有帮助.

推荐答案

要更新，您需要执行以下操作:

To update, you need to do this:

DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("Matches").child("Match_01");
Map<String, Object> updates = new HashMap<String,Object>();

updates.put("matchID", newID);
updates.put("homeScore", newscore);
//etc

ref.updateChildren(updates);

更多信息在这里:

https://firebase.google.com/docs /database/android/read-and-write#update_specific_fields

要同时写入节点的特定子节点而不覆盖其他子节点，请使用updateChildren()方法.

To simultaneously write to specific children of a node without overwriting other child nodes, use the updateChildren() method.

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