Android Firebase数据库添加带有密钥的项目到回收者视图 [英] Android Firebase Database Adding items with keys to recycler view
问题描述
我正在尝试添加&在回收器视图中动态显示消息，但我不知道如何向其适配器发送正确的数据类型.在"getNewMessage(dataSnapshot)"函数中，我必须将所有消息添加到列表中，然后通过适配器将其发送到回收者视图.我都尝试过
MessageModel model = dataSnapshot.getValue(MessageModel.class)
并创建一个包含List<MessageModel> list的SampleModel，并
SampleModel model = dataSnapshot.getValue(SampleModel.class);
他们没有工作.这里是通过发送消息创建的示例JSON文件:
I was trying to add & show messages dynamically in recycler view but I could not figure out how to send proper data type to it's adapter. In "getNewMessage(dataSnapshot) " function, I have to add all messages to list and send it to recycler view via adapter. I tried both
MessageModel model = dataSnapshot.getValue(MessageModel.class)
and creating a SampleModel that contains List<MessageModel> list, and
SampleModel model = dataSnapshot.getValue(SampleModel.class);
They didn't work. Here sample JSON file that created with sending message:
"chat" : {
"-Ksbjn0yCEB6EXhNNCM5" : {
"author" : "Ali Alacan",
"content" : "dummy content",
"date" : "Mon Aug 28 10:29:50 GMT+03:00 2017",
"id" : "H6huNPUggjtugjsERPCRSAp1"
},
"-KsbjpUtjp0oeipjjxMI" : {
"author" : "Ali Alacan",
"content" : "dummy content",
"date" : "Mon Aug 28 10:30:00 GMT+03:00 2017",
"id" : "H6huNPUggjtugjsERPCRSAp1"
}
我要添加新消息，并在其中添加以下代码，这些代码是我从firebase文档中学到的.
I'm adding new messages with code below which I learnt from firebase docs.
@Exclude
public Map<String, Object> toMap(MessageModel messageModel) {
HashMap<String, Object> result = new HashMap<>();
result.put("id", messageModel.getId());
result.put("author", messageModel.getAuthor());
result.put("content", messageModel.getContent());
result.put("date", messageModel.getDate());
return result;
}
private void sendMessage() {
if (!TextUtils.isEmpty(etMessage.getText())) {
Date currentTime = Calendar.getInstance().getTime();
String key = firebaseDatabase.push().getKey();
MessageModel message = new MessageModel(UserData.getInstance().getUserId(), UserData.getInstance().getName(), "dummy content", currentTime.toString());
Map<String, Object> messageValues = toMap(message);
Map<String, Object> childUpdates = new HashMap<>();
childUpdates.put("/chat/" + key, messageValues);
childUpdates.put("/user-chat/" + UserData.getInstance().getUserId() + "/" + key, messageValues);
firebaseDatabase.updateChildren(childUpdates);
} else {
Snackbar snackbar = Snackbar
.make(getActivity().findViewById(R.id.dashboard_container), "Enter a message please ! " + UserData.getInstance().getName(), Snackbar.LENGTH_LONG);
snackbar.show();
}
}
我的MessageModel是:
My MessageModel is:
public class MessageModel {
String id;
String author;
String content;
String date;
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public MessageModel(String id, String author, String content, String date) {
this.id = id;
this.author = author;
this.content = content;
this.date = date;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public MessageModel() {
}
}
和Firebase监听器
And firebase listener
firebaseDatabase.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
getNewMessage(dataSnapshot);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
// getNewMessage(dataSnapshot);
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
// taskDeletion(dataSnapshot);
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
RecyclerView适配器:
RecyclerView Adapter:
public class MyMessageRecyclerViewAdapter extends RecyclerView.Adapter<MyMessageRecyclerViewAdapter.ViewHolder> {
private final List<MessageModel> mValues;
private final OnListFragmentInteractionListener mListener;
public MyMessageRecyclerViewAdapter(List<MessageModel> items, OnListFragmentInteractionListener listener) {
mValues = items;
mListener = listener;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_chat, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.mItem = mValues.get(position);
holder.mIdView.setText(mValues.get(position).getId());
holder.mContentView.setText(mValues.get(position).getContent());
holder.mAuthor.setText(mValues.get(position).getAuthor());
holder.mDate.setText(mValues.get(position).getDate());
holder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mListener.onListFragmentInteraction(holder.mItem);
}
}
});
}
@Override
public int getItemCount() {
return mValues.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public final View mView;
public final TextView mIdView;
public final TextView mContentView;
TextView mAuthor;
TextView mDate;
public MessageModel mItem;
public ViewHolder(View view) {
super(view);
mView = view;
mIdView = (TextView) view.findViewById(R.id.id);
mContentView = (TextView) view.findViewById(R.id.content);
mAuthor = (TextView) view.findViewById(R.id.author);
mDate = (TextView) view.findViewById(R.id.date);
}
@Override
public String toString() {
return super.toString() + " '" + mContentView.getText() + "'";
}
}
很抱歉阅读了这么长的帖子，并感谢您的宝贵时间.
Sorry for reading such a long post and thank you for your time.
推荐答案
您不再需要使用toMap，因为您已经有POJO，这使您对正在做的事情更加困惑.
You don't need to use your toMap anymore, it is making you more confused on what you're doing since You already have a POJO.
在活动中列出清单.
ArrayList<MessageModel> myListModel = new ArrayList<MessageModel>();
在您的Firebase侦听器上执行此操作.列出您的活动
Do this on your firebase Listener. Make a List on your Activity
这是给添加的孩子的.
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
MessageModel tempMessage = dataSnapshot.getValue(MessageModel.class);
myListModel.add(tempRace);
}
现在您有了一个列表模型.通过使用Firebase的onChildAdeed. 使用它来提供适配器模型并应用它.
Now That you have a List Model. By using the onChildAdeed by Firebase. Use this to your supply your Adapter Model and apply it.
重要的防火墙.在firebase的每个查询中，如果您需要在执行其他操作之后执行其他操作，例如:"onChildAdded"，则需要为您的情况向THE SAME DatabaseReference添加另一个侦听器.我不知道，您甚至没有包含您的活动，甚至没有DatabaseReference，所以我会提供一个.
IMPORTANT FOR FIREBASE. In everyquery for the fire base, if you need to do something AFTER the anything else is done ex: "onChildAdded" You would need to add another listener to THE SAME DatabaseReference in your case. I have no idea, you did not include your activity even your DatabaseReference so I would provide one.
DatabaseReference myReference = firebaseDatabase.getReferane("chat");
myReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
MyMessageRecyclerAdapter myMessageAdapter= new MyMessageRecyclerAdapter(myListModel, listener);
//now you have to apply this to the RecyclerView.
yourWhateverNameofTheRecyclerview.SetAdapter(myMessageAdater);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
这篇关于Android Firebase数据库添加带有密钥的项目到回收者视图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
