如何搜索给定的Firebase数据库中是否存在用户名? [英] How to search if a username exist in the given firebase database?
问题描述
{
users:
{
apple:
{
username : apple
email : apple@xy.com
uid : tyutyutyu
}
mango:
{
username : mango
email : mango@xy.com
uid : erererer
}
}
}
这就是我在做什么 如果checkUsername方法返回0，则创建用户
This is what I am doing CREATING USER if checkUsername method returns 0
if(checkFirebaseForUsername(username)==0) {
mAuth.createUserWithEmailAndPassword(email, password)
.addOnCompleteListener(SignUpActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
Toast.makeText(getBaseContext(),"inside",Toast.LENGTH_LONG).show();
User newUser = new User();
newUser.setUserId(mAuth.getCurrentUser().getUid());
newUser.setUsername(username);
newUser.setEmailId(email);
try{
mRef.child("users").child(username).setValue(newUser);
}
catch(Exception e){
Toast.makeText(SignUpActivity.this,"error while inserting",Toast.LENGTH_LONG).show();
}
AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
builder.setTitle(R.string.signup_success)
.setPositiveButton(R.string.login_button_label, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Intent intent = new Intent(SignUpActivity.this, LoginActivity.class);
startActivity(intent);
finish();
}
});
AlertDialog dialog = builder.create();
dialog.show();
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
builder.setTitle(R.string.signup_error_title)
.setPositiveButton(android.R.string.ok, null);
AlertDialog dialog = builder.create();
dialog.show();
}
}
我的checkUsername方法-
My checkUsername method -
public int checkFirebaseForUsername(String passedUsername){
final int[] flag = {0};
final String myPassedUsername = passedUsername;
Log.e("tag","working now");
//flag[0]=1;
DatabaseReference mTest = FirebaseDatabase.getInstance().getReference();
mTest.child("users").child(passedUsername).addChildEventListener(new ChildEventListener() {
@Override
public void onDataChanged(DataSnapshot dataSnapshot) {
Log.e("tag","checking");
if(dataSnapshot.exists()){
Log.e("tag","exists");
flag[0]=1;
}
}
@Override
public void onCancelled(DataSnapshot datasnapshot){
}
});
if(flag[0]==1)
return 1;
else
return 0;
}
这是我在 firebase数据库中插入用户的方式，我想检查用户名是否可用于新用户.
This is how I am inserting users in my firebase-database and I want to check if a username is available for a new user or not.
因此，我需要检查是否有已经使用该用户名注册的用户....请帮助我，在参考Firebase官方博客上提供的文档之后，我已经尝试了所有我能理解的内容，但是一切都是徒劳的！
Therefore I need to check is there any user already registered with that username....Please help I have already tried whatever I could understand after reffering to documentation provided on the official firebase blog but all in vain!!
推荐答案
新答案，旧答案仍在下面.
New answer, old one still below.
我将摆脱方法"checkFirebaseForUsername"，因为无论如何它总是返回0.
I would get rid of your method "checkFirebaseForUsername" because it will always return 0, no matter what.
您需要做的是这样
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
ref.child("users").child("username").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()){
// use "username" already exists
// Let the user know he needs to pick another username.
} else {
// User does not exist. NOW call createUserWithEmailAndPassword
mAuth.createUserWithPassword(...);
// Your previous code here.
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
旧答案:
{
users:
{
apple[X]:
{
username : apple[Y]
email : apple@xy.com
uid : tyutyutyu
}
mango:
{
username : mango
email : mango@xy.com
uid : erererer
}
}
}
例如，如果节点apple [X]始终与子属性"username":apple [Y]具有相同的名称，那么就这么简单.
If for example, the node apple[X] will always have the same name as the child property "username":apple[Y], then it is as simple as this.
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
ref.child("users").child("username").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()){
// use "username" already exists
} else {
// "username" does not exist yet.
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
但是，如果说，节点apple [X]可以具有与属性apple [Y]不同的值，并且您想查看是否存在"username"属性相同的任何节点，那么您将需要进行查询.
however, if say, the node apple[X] can have a different value than the property apple[Y], and you want to see if any node exists where the "username" property is the same, then you will need to do a query.
Query query = FirebaseDatabase.getInstance().getReference().child("users").orderByChild("username").equalTo("usernameToCheckIfExists");
query.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.getChildrenCount() > 0) {
// 1 or more users exist which have the username property "usernameToCheckIfExists"
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
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