我们如何获取 Firebase 实时数据库到 List

Question

我在这里尝试将“用户”显示到 Recycleview 中，我需要将数据放入列表中

databaseReference?.addValueEventListener(object : ValueEventListener {
            override fun onDataChange(dataSnapshot: DataSnapshot) {
                val list = dataSnapshot.child("users")

                for (e in dataSnapshot.children) {
                    Log.i("messageData", e.toString())
                }
                Log.i("messageData", userList.toString())
            }

            override fun onCancelled(databaseError: DatabaseError) {
                Toast.makeText(
                    this@MessageActivity, "database error",
                    Toast.LENGTH_SHORT
                ).show()
            }
        })

Realtime Database Users Sample

Answer 1

您可以像下面的例子一样得到列表：

databaseReference?.addValueEventListener(object : ValueEventListener {
    override fun onDataChange(dataSnapshot: DataSnapshot) {
        val userList = dataSnapshot.children.map { snap -> User(
            snap.child("Name").getValue(String::class.java)?:"",
            snap.child("email").getValue(String::class.java)?:"",
            snap.child("phone").getValue(Long::class.java)?:0,
        ) }
    }

    override fun onCancelled(databaseError: DatabaseError) {
        Toast.makeText(
            this@MessageActivity, "database error",
            Toast.LENGTH_SHORT
        ).show()
    }
})

Answer 2

在这里，我得到了我的解决方案

    private val userList: ArrayList<UserList> = ArrayList()

        databaseReference?.addValueEventListener(object : ValueEventListener {
            override fun onDataChange(dataSnapshot: DataSnapshot) {
                for (data in dataSnapshot.children) {

                    val model = data.getValue(UserList::class.java)
                    if (personalEmail != model?.email)
                        userList.addAll(listOf(model as UserList))

                }
            }

#用户列表class

data class UserList(
    val email: String? = null,
    val full_name: String? = null,
    val phoneNumber: String? = null,
    val profile_image: String? = null
)

我们如何获取 Firebase 实时数据库到 List

How can we fetch the Firebase realtime database to List

android

kotlin

firebase-realtime-database