Flutter - Store User Details Using Firebase

import 'dart:io';
import 'package:image_picker/image_picker.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';

class RealtimeDatabaseInsert extends StatelessWidget {
  RealtimeDatabaseInsert({Key? key}) : super(key: key);

 var nameController = new TextEditingController();
 var ageController = new TextEditingController();
 var dlController = new TextEditingController();
 var adController = new TextEditingController();
 var phnController = new TextEditingController();

   final firestore=FirebaseFirestore.instance;
 get data => null;
 @override
 Widget build(BuildContext context) {
   return Center(
       child: Scaffold(
     body: SafeArea(
       child: SingleChildScrollView(
         child: Padding(
           padding: const EdgeInsets.all(20.0),
           child: Column(
             children: [
               Text(
                 'Insert Driver Details',
                 style: TextStyle(fontSize: 28),
               ),
             
               SizedBox(
                 height: 30,
               ),
               SizedBox(
                 height: 50,
               ),
               TextFormField(
                 controller: nameController,
                 maxLength: 15,
                 decoration: InputDecoration(
                     labelText: 'Name', border: OutlineInputBorder()),
               ),
               SizedBox(
                 height: 15,
               ),
               TextFormField(
                 controller: ageController,
                 keyboardType: TextInputType.number,
                 decoration: InputDecoration(
                     labelText: 'Age', border: OutlineInputBorder()),
               ),
               SizedBox(
                 height: 15,
               ),
               TextFormField(
                 controller: dlController,
                 maxLength: 20,
                 decoration: InputDecoration(
                     labelText: 'Driving Licencse Number',
                     border: OutlineInputBorder()),
               ),
               SizedBox(
                 height: 15,
               ),
               TextFormField(
                 controller: adController,
                 decoration: InputDecoration(
                     labelText: 'Address', border: OutlineInputBorder()),
               ),
               SizedBox(
                 height: 15,
               ),
               TextFormField(
                 controller: phnController,
                 maxLength: 10,
                 keyboardType: TextInputType.number,
                 decoration: InputDecoration(
                     labelText: 'Phone No.', border: OutlineInputBorder()),
               ),
               SizedBox(
                 height: 20,
               ),
               ElevatedButton(
                 onPressed: () async {
                   if (nameController.text.isNotEmpty &&
                       ageController.text.isNotEmpty &&
                       dlController.text.isNotEmpty &&
                       adController.text.isNotEmpty &&
                       phnController.text.isNotEmpty) {
                     firestore.collection("Driver Details").add({
                         "Name": nameController.text,
                         "Age": ageController.text,
                         "Driving Licence": dlController.text,
                         "Address.": adController.text,
                         "Phone No.": phnController.text
                     });
                   }
                   },
                 child: Text(
                   "Submit Details",
                 ),
                 style: ElevatedButton.styleFrom(
                     backgroundColor: Colors.amber,
                     shape: RoundedRectangleBorder(
                         borderRadius: BorderRadius.circular(10))),
               )
             ],
           ),
         ),
       ),
     ),
   ));
 }
}