从firebase数据库中获取recyclerview中子项单击时的父键值 [英] Get parent key value on click of child in recyclerview from firebase database

问题描述

我正在创建一个回收者视图，在其中，我得到的调查名称是Firebase数据库中调查参考编号的子代.我想要的是，当用户在recyclerview列表中单击调查名称时，它将获得父KeyValue(这是调查参考编号).我已附上数据库的图像.在点击调查名称用蓝色线围起来时，我希望父键用黄色线阴影

I am creating a recycler view in which, I am getting Survey Name which is child of survey reference number in firebase database. What I want is when user click on survey name in recyclerview list it gets the parent KeyValue (which is survey reference number). I have attached the image of the database. On click survey name encircled which blue line, I want the parent key shaded with yellow line

我在适配器类中使用了一个接口，在那里我要获取位置和modelResponse

I have used an Interface in adapter class where I am getting position and modelResponse

public SurveysListAdapter(List<SurveysListModel> modelList, Context context, HandleClickListener handleClickListener)
 {
        this.modelList = modelList;
        this.context = context;
        this.handleClickListener = handleClickListener;
    }

    @Override
    public void onBindViewHolder(@NonNull final SurveyListViewHolder holder, final int position) {
        final SurveysListModel response = modelList.get(position);
        holder.questions.setText(response.getSurvey_name());
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleClickListener.onItemClicked(position, modelList.get(position));
            }
        });
    }
    public interface HandleClickListener {
        void onItemClicked(int position, SurveysListModel surveysListModel);
    }

然后在Activity Iam中获得它

Then in Activity Iam getting it like this

databaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                for (final DataSnapshot parentSnap : dataSnapshot.getChildren()) {

                    if (parentSnap.exists()) {
                        progressDialog.dismiss();
                        SurveysListModel model = parentSnap.getValue(SurveysListModel.class);
                        list.add(model);

                        adapter = new SurveysListAdapter(list, UserAllSurveys.this, new SurveysListAdapter.HandleClickListener() {
                            @Override
                            public void onItemClicked(int position, SurveysListModel surveysListModel) {
                                String typ = surveysListModel.getSurvey_name();
                                Toast.makeText(UserAllSurveys.this, "CLicked" + position, Toast.LENGTH_SHORT).show();
                            }
                        });
                        recyclerView.setAdapter(adapter);
                    }

推荐答案

要允许此操作，您需要做两件事:

To allow this, you'll need to do two things:

1. 使 parentSnap.getKey()值可用于适配器，就像对 parentSnap.getValue(...)对象所做的一样.
2. 通常通过按位置查找来查找用户单击的值的正确键.

1. Make the parentSnap.getKey() values available to your adapter, just as you already do for the parentSnap.getValue(...) objects.
2. Look up the correct key for the value the user has clicked on, typically by looking it up by its position.

要使密钥可用，您再次有两个选择:

To make the keys available, you again have two options:

1. 为此键的一个字段添加到您的 SurveysListModel 类，然后在获取值后进行设置.

1. Add a field for this key to your SurveysListModel class, and then set that after getting the value.

维护一个单独的 List< String>除了现有的 List< SurveysListModel> keyList modelList 并将它们都传递给适配器的构造函数.

Maintain a separate List<String> keyList in addition to your existing List<SurveysListModel> modelList and pass both to the constructor of your adapter.

对于这两种情况，代码看起来都是相似的，所以我只着重于如何获取密钥，然后例如将其传递给``对象(上面的#1):

For both cases the code will look similar, so I'll just focus on how to get the key and then for example pass it into the `` object (so #1 above):

public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

    for (final DataSnapshot parentSnap : dataSnapshot.getChildren()) {
        progressDialog.dismiss();
        SurveysListModel model = parentSnap.getValue(SurveysListModel.class);
        model.key = parentSnap.getKey();
        list.add(model);
    }

    adapter = new SurveysListAdapter(list, UserAllSurveys.this, new SurveysListAdapter.HandleClickListener() {
        @Override
        public void onItemClicked(int position, SurveysListModel surveysListModel) {
            String typ = surveysListModel.getSurvey_name();
            String key = surveysListModel.key;
            Toast.makeText(UserAllSurveys.this, "CLicked " + key, Toast.LENGTH_SHORT).show();
        }
    });
    recyclerView.setAdapter(adapter);

我在这里所做的更改:

1. 删除 if(parentSnap.exists()){，因为在 getChildren()的循环中无法将其设为false.

2. 将密钥传递给 model.key = parentSnap.getKey(); .您将必须将此 key 字段添加到您的类中，并可能将其标记为 @Exclude ，以确保它不会被写入数据库:

1. Remove the if (parentSnap.exists()) {, since there is no way for this to be false in a loop over getChildren().

2. Pass the key to model.key = parentSnap.getKey();. You will have to add this key field to your class, and probably mark it as @Exclude to make sure it doesn't get written to the database:

@Exclude 
String key;

将整个 adapter = new SurveysListAdapter 块移到 getChildren()的循环外，我认为这是您原始文档中的复制/粘贴错误代码.

Move the whole adapter = new SurveysListAdapter block outside of the loop over the getChildren(), which I assume was a copy/paste mistake in your original code.

当用户单击某个项目时，使用 String key = surveysListModel.key; 从对象读取它们的密钥.

Read they key back from the object with String key = surveysListModel.key; when the user clicks on an item.

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