Flutter with Firebase Realtime Database

Add following dependency in pubspec.yaml file:

firebase_database: ^6.1.2

Create a project in Firebase Console

Go To Firebase Console

Add Package Name

Apply Following Plugin in android/app/build.gradle file:

Add Classpath in android/build.gradle file:

firebase.dart

import 'package:firebase_database/firebase_database.dart';
import 'package:firebase_database/ui/firebase_animated_list.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: "Firebase CRUD Tutorial",
    home: MyHomeWidget(),
  ));
}

class MyHomeWidget extends StatefulWidget {
  Container mycontainer = Container();

  @override
  _MyHomeWidgetState createState() => _MyHomeWidgetState();
}

class _MyHomeWidgetState extends State<MyHomeWidget> {
 final databaseReference = FirebaseDatabase.instance.reference();
 final name = TextEditingController();
 final email = TextEditingController();
 final mobile = TextEditingController();
 final _formKey = GlobalKey<FormState>();
 String key = "";

 @override
 Widget build(BuildContext context) {
   return Scaffold(
     appBar: AppBar(
       title: Text("Firebase CRUD"),
     ),
     body: SingleChildScrollView(
        
      child: Form(
      key: _formKey,
      child: Container(
      child: Column(
        children: [
           
       Container(
        margin: EdgeInsets.only(left: 20, right: 20, top: 20),
        child: TextFormField(
        controller: name,
        //onChanged: (value) => name.text=value,
        validator: (value) =>
        (value.isEmpty) ? "Please enter name" : null,
        decoration: InputDecoration(
        prefixIcon: Icon(Icons.drive_file_rename_outline),
        labelText: "Name Here",
        border: OutlineInputBorder(
        gapPadding: 2,
          ),
        ),
       ),
     ),
                
        Container(
         margin: EdgeInsets.only(left: 20, right: 20, top: 20),
         child: TextFormField(
         controller: email,
         /*onChanged: (value) {
           setState(() {
           email.text = value;
          });
        },*/
          
        validator: (value) =>
         (value.isEmpty) ? "Please enter email" : null,
         decoration: InputDecoration(
         prefixIcon: Icon(Icons.email),
         labelText: "Email Here",
         border: OutlineInputBorder(
         gapPadding: 2,
          ),
         ),
        ),
       ),
         
        Container(
         margin: EdgeInsets.only(left: 20, right: 20, top: 20),
         child: TextFormField(
         controller: mobile,
         /*onChanged: (value) {
         setState(() {
         mobile.text = value;
       });
      },*/
      
        validator: (value) =>
         (value.isEmpty) ? "Please enter mobile" : null,
         decoration: InputDecoration(
         prefixIcon: Icon(Icons.call),
         labelText: "Mobile Here",
         border: OutlineInputBorder(
         gapPadding: 2,
         ),
         ),
         ),
         ),
         SizedBox(
         height: 20,
        ),
      
       Container(
        margin: EdgeInsets.only(left: 20, right: 20, top: 20),
        width: MediaQuery.of(context).size.width,
        child: ElevatedButton(
        child: Text("Add Me"),
             
         onPressed: () {
          if (_formKey.currentState.validate()) {
          insert(Student(
          name: name.text,
          email: email.text,
          mobile: mobile.text,
          key: ""));
          _formKey.currentState.reset();
         }
        },
      ),
     ),
      
       Container(
       margin: EdgeInsets.only(
       left: 20,
       right: 20,
      ),
                  
      width: MediaQuery.of(context).size.width,
      child: ElevatedButton(
      child: Text("Fetch All"),
      onPressed: () {
      fetchAllInWidget().then((value) {
      print(value);
      widget.mycontainer = value;
     });
    },
   ),
  ),
  
       Container(
        margin: EdgeInsets.only(
        left: 20,
        right: 20,
     ),
        width: MediaQuery.of(context).size.width,
        child: ElevatedButton(
        child: Text("Update"),
    
        onPressed: () {
        setState(() {
        databaseReference
        .child("student")
        .child(key)
        .update(Student(
         name: name.text,
         email: email.text,
         mobile: mobile.text,
         key: key).toMap()).then((value) => {
          print("update successfully " + key),
         });
       });
      },
    ),
  ),
      
      Container(
      child: widget.mycontainer,),
         ],
        ),
       ),
      ),
     ),
    );
  }

 void insert(Student student) {
    setState(() {
 var databaseReference1 = databaseReference.
 child("student").push();

 student.key = databaseReference1.key;
 databaseReference1.set(student.toMap())
 .whenComplete(
        () => () {
          print("Successfully Added");
         },
        );
    });
  }

 void fetchAllDatabase() {
    databaseReference.child("student").
    onValue.listen((event) {
      var snap = event.snapshot;
      setState(() {
        print(snap.value);
      });
    });
  }

  Future<List<Student>> fetchAll() async {
  
  List<Student> students = [];

  databaseReference.child("student").
  once().then((value) => {
     
      for (var val in value.value.entries)
       {
        students.add(
         Student(
           name: val.value["name"],
           email: val.value["email"],
           mobile: val.value["mobile"],
           key: val.key,
          ),
         ),
       }
     });
    print("fetching completed...");
    //fetchAllDatabase();
    return students;
  }

  Future<Widget> fetchAllInWidget() async {
    return Container(
      child: FirebaseAnimatedList(
          shrinkWrap: true,
          padding: new EdgeInsets.all(8.0),
          reverse: false,
          //duration: Duration(seconds: 5),
          query: databaseReference.child("student").orderByValue(),
          itemBuilder: (context, snapshot, animation, index) {
            return Card(
             child: ListTile(
             title: Text(snapshot.value["name"]),
             subtitle: Text(snapshot.value["email"]),
             trailing: Container(
             child: Row(
             mainAxisSize: MainAxisSize.min,
             mainAxisAlignment: MainAxisAlignment.start,
             children: [
             IconButton(
             icon: Icon(
             Icons.edit,
             ),
             
             onPressed: () {
             setState(() {
             key = snapshot.key;
             name.text = snapshot.value["name"].toString();
             email.text = snapshot.value["email"].toString();
             mobile.text = snapshot.value["mobile"].toString();
             print("Hello " + key);
             });
             },
             ),
                      
             IconButton(
             icon: Icon(
             Icons.delete,
             ),
                        
             onPressed: () {
             setState(() {
             databaseReference
             .child("student")
             .child(snapshot.key)
             .remove()
             .then((value) => {
             print("deleted.."),
           });
          });
         },
        ),
       ],
      ),
     ),
    ),
   );
  }),
);
}

  Future delete(Student student) async {
    print(student.name);
    print(student.key);
    await databaseReference.child(student.key).remove();
  }
}

class Student {
  String name, email, mobile, key;

  Student({this.name, this.email, this.mobile, this.key});

  Map<String, dynamic> toMap() {
    return {
      'name': name,
      'email': email,
      "mobile": mobile,
      "key": key,
    };
  }

  Student.fromMap(dynamic obj) {
    this.name = obj['name'];
    this.email = obj['email'];
    this.mobile = obj['mobile'];
    this.key = obj["key"];
  }
}