I want check internet connection before every dio request using interceptor and connectivity package in flutter

1.First you should Install connectivity package into you’r project.you can add it using bellow cammand,

flutter pub add connectivity_plus

2.Now you should import into you’r workspace. import

'package:connectivity_plus/connectivity_plus.dart';

you can refer it by using this link.

3.Set up an interceptor to check the internet connection before each Dio request. Create a class that extends Interceptor from Dio package: look at bellow code segment,

import 'package:dio/dio.dart';
import 'package:connectivity/connectivity.dart';

class ConnectivityInterceptor extends Interceptor {
  final Connectivity connectivity;

  ConnectivityInterceptor(this.connectivity);

  @override
  Future onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
    var connectivityResult = await connectivity.checkConnectivity();
    if (connectivityResult == ConnectivityResult.none) {
      // Handle case when there is no internet connection
      throw DioError(
        requestOptions: options,
        response: Response(
          requestOptions: options,
          statusCode: 503, // You can set your custom status code
          statusMessage: 'No internet connection',
        ),
      );
    }
    return super.onRequest(options, handler);
  }
}

4.In your main function or where you configure Dio, set up the Dio instance with the interceptor:

import 'package:flutter/material.dart';
import 'package:dio/dio.dart';
import 'package:connectivity/connectivity.dart';

void main() {
  Dio dio = Dio();
  Connectivity connectivity = Connectivity();
  dio.interceptors.add(ConnectivityInterceptor(connectivity));
  
  runApp(MyApp(dio: dio));
}

class MyApp extends StatelessWidget {
  final Dio dio;

  MyApp({required this.dio});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Dio Connectivity Example'),
        ),
        body: Center(
          child: ElevatedButton(
            onPressed: () {
              makeDioRequest();
            },
            child: Text('Make Dio Request'),
          ),
        ),
      ),
    );
  }

  Future<void> makeDioRequest() async {
    try {
      Response response = await dio.get('https://api.example.com/data');
      print('Response: ${response.data}');
      // Handle the response
    } on DioError catch (e) {
      if (e.response != null && e.response!.statusCode == 503) {
        // Handle case when there is no internet connection
        print('No internet connection');
        // Show a dialog or snackbar indicating no internet
      } else {
        // Handle other Dio errors
        print('Dio error: $e');
        // Show a dialog or snackbar with the error
      }
    }
  }
}

class ConnectivityInterceptor extends Interceptor {
  final Connectivity connectivity;

  ConnectivityInterceptor(this.connectivity);

  @override
  Future onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
    var connectivityResult = await connectivity.checkConnectivity();
    if (connectivityResult == ConnectivityResult.none) {
      // Handle case when there is no internet connection
      throw DioError(
        requestOptions: options,
        response: Response(
          requestOptions: options,
          statusCode: 503, // You can set your custom status code
          statusMessage: 'No internet connection',
        ),
      );
    }
    return super.onRequest(options, handler);
  }
}

I use simple app with button, you can give some idea using this guidelines.