[Flutter] CRUD Firebase Realtime Database

Create “dbRef” object to work with Firebase database and RaisedButton for testing functions.

import 'package:firebase_database/firebase_database.dart';
final dbRef = FirebaseDatabase.instance.reference();
RaisedButton(
    child: Text('Create Record'),
    onPressed: () {
      createRecord();
    },
),

1. Create

Here we could use “set” or “update”, both are OK

void createRecord() async {
  dbRef.child('students/ABLE1-9999').set({
    'name' : 'Nguyễn Thanh Bình',
    'token': [null, '9999']
  });
}

Output

2. Read

2.1 Read all database

void readDatabase(){
  dbRef.once().then((DataSnapshot snapshot) {
    print('Data : ${snapshot.value}');
  });
}

2.2 Read all childs

class Student {
  String id;
  String name;
  String dob;
  String allInfo;
Student(this.id, this.name, this.dob, this.allInfo);
}
List<Student> studentList = <Student>[];
void readAllChild() async {
  studentList.clear();
  await dbRef.child('students')
       .once().then((DataSnapshot snapshot) {
    print('Data : ${snapshot.value}');
    Map<dynamic, dynamic> values = snapshot.value;
    print('Loop all returned data to extract values...');
    values.forEach((k, v) {
      print('Student id                =' + k);
      print('Student info              =' + v.toString());
      print('Student info -> name      =' + v['name']);
      Student student = Student(k, v['name'], v['dob'], v.toString());
      studentList.add(student);
    });
    print('studentList.length=' + studentList.length.toString());
  });
}

Output

2.3 Read a particular child

void readRecord() async {
  await dbRef.child('students/ABLE1-2021')
       .once().then((DataSnapshot snapshot) {
    print('Data : ${snapshot.value}');
    String name  = snapshot.value['name'].toString();
    String token = snapshot.value['token'].toString();
 
    print('name           = ' + name);
    print('token          = ' + token);
    List<dynamic> strTokenArr = snapshot.value['token'].toList();
    print('Token[1]       = ' + strTokenArr[1].toString());
  });
}

Output

3. Update

void updateRecord() async {
  //for array, we need to find & store it into List firstly
  List<dynamic> strTokenArr;
  await dbRef.child('students/ABLE1-2021')
       .once().then((DataSnapshot snapshot) {
    print('Data : ${snapshot.value}');
    //add new item to list
    strTokenArr = snapshot.value['token'].toList();
    strTokenArr.add('NewTokenHere');
  });
  //update data
  dbRef.child('students/ABLE1-2021').update({
    'name': 'Nguyễn Thanh Bình new', //update string
    'token': strTokenArr             //update array
  });
}

Output

4. Delete

void deleteRecord(){
  dbRef.child('students/ABLE1-9999').remove();
}

5. Listen changes on realtime databse with StreamBuilder & FutureBuilder

Demo Code