API handling using BLOC in Flutter

 import "package:bloc_wslc_statemanagement/Api_handling_using_Bloc/Custom_Class/api_helper.dart";

import "package:bloc_wslc_statemanagement/Api_handling_using_Bloc/bloc/quote_bloc.dart";
import "package:bloc_wslc_statemanagement/Api_handling_using_Bloc/bloc/quote_event.dart";
import "package:bloc_wslc_statemanagement/Api_handling_using_Bloc/bloc/quote_state.dart";
import "package:flutter/material.dart";
import "package:flutter_bloc/flutter_bloc.dart";

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "Home Page",
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        appBarTheme: const AppBarTheme(
          backgroundColor: Colors.grey,
          centerTitle: true,
        ),
      ),
      home: BlocProvider(
        create: (context) {
          return QuoteBloc(apiHelper: ApiHelper());
        },
        child: const HomePage(),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() {
    return HomePageState();
  }
}

class HomePageState extends State<HomePage> {
  @override
  void initState() {
    super.initState();
    BlocProvider.of<QuoteBloc>(context).add(GetQuotesEvent());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text(
          "Quotes",
          style: TextStyle(fontWeight: FontWeight.bold),
        ),
      ),
      body: BlocBuilder<QuoteBloc, QuoteState>(
        builder: (context, state) {
          if (state is QuoteLoadingState) {
            return const Center(
              child: CircularProgressIndicator(),
            );
          } else if (state is QuoteErrorState) {
            return Center(
              child: Text(state.errormsg),
            );
          } else if (state is QuoteLoadedState) {
            var mDataModel = state.resData;

            return ListView.builder(
              itemCount: mDataModel.quotes?.length,
              itemBuilder: (context, index) {
                var eachQuote = mDataModel.quotes![index];
                return Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: Card(
                    elevation: 7.0,
                    child: ListTile(
                      title: Text("${eachQuote.quote}"),
                      subtitle: Text("${eachQuote.author}"),
                    ),
                  ),
                );
              },
            );
          }
          return Container();
        },
      ),
    );
  }
}

import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/Custom_Class/api_helper.dart';
import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/Model/quote_model.dart';
import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/Urls/urls.dart';
import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/app_exceptions.dart';
import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/bloc/quote_event.dart';
import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/bloc/quote_state.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class QuoteBloc extends Bloc<QuoteEvent, QuoteState> {
  ApiHelper apiHelper;

  QuoteBloc({required this.apiHelper}) : super(QuoteInitialState()) {
    on<QuoteEvent>(
      (event, emit) async {
        emit(QuoteLoadingState());

        try {
          var resJson = await apiHelper.getAPI(url: Urls.getQuotesUrl);
          if (resJson != null) {
            var mResData = DataModel.fromJson(resJson);
            emit(QuoteLoadedState(resData: mResData));
          } else {
            emit(QuoteErrorState(errormsg: "Uhh..No!!, Error Occurred"));
          }
        } catch (e) {
          emit(QuoteErrorState(errormsg: (e as AppExceptions).toErrorMsg()));
        }
      },
    );
  }
}

import "dart:convert";
import "dart:io";
import "package:bloc_wslc_statemanagement/Api_handling_using_Bloc/app_exceptions.dart";
import "package:http/http.dart" as http;

class ApiHelper {
  Future<dynamic> getAPI({required String url}) async {
    var uri = Uri.parse(url);

    try {
      var response = await http.get(uri);
      return returnJsonResponse(response);
    } on SocketException catch (e) {
      throw (FetchDataException(errorMsg: "No Internet!!"));
    }
  }

  Future<dynamic> postAPI(
      {required String url, Map<String, dynamic>? bodyParams}) async {
    var uri = Uri.parse(url);
    var response = await http.post(uri, body: bodyParams ?? {});

    if (response.statusCode == 200) {
      var mData = jsonDecode(response.body);
    }
  }

  dynamic returnJsonResponse(http.Response response) {
    switch (response.statusCode) {
      case 200:
        {
          var mData = jsonDecode(response.body);
          return mData;
        }
      case 400:
        throw BadRequestException(errorMsg: response.body.toString());
      case 401:
      case 403:
        throw UnauthorisedException(errorMsg: response.body.toString());
      case 500:
      default:
        throw FetchDataException(
            errorMsg:
                "Error occurred while Communication with Server with StatusCode : ${response.statusCode}");
    }

    if (response.statusCode == 200) {
      var mData = jsonDecode(response.body);
      return mData;
    } else {
      return null;
    }
  }
}

class AppExceptions implements Exception {
  String title;
  String msg;

  AppExceptions({required this.title, required this.msg});

  String toErrorMsg() {
    return "$title: $msg";
  }
}

class FetchDataException extends AppExceptions {
  FetchDataException({required String errorMsg})
      : super(title: "Network Error", msg: errorMsg);
}

class BadRequestException extends AppExceptions {
  BadRequestException({required String errorMsg})
      : super(title: "Invalid Request: ", msg: errorMsg);
}

class UnauthorisedException extends AppExceptions {
  UnauthorisedException({required String errorMsg})
      : super(title: "Unauthorised: ", msg: errorMsg);
}

class InvalidInputException extends AppExceptions {
  InvalidInputException({required String errorMsg})
      : super(title: "", msg: errorMsg);
}

class Urls {
  static final String getQuotesUrl = "https://dummyjson.com/quotes";
}

class QuoteEvent {}

class GetQuotesEvent extends QuoteEvent {}

import 'package:bloc_wslc_statemanagement/Api_handling_using_Bloc/Model/quote_model.dart';

class QuoteState {}

class QuoteInitialState extends QuoteState {}

class QuoteLoadingState extends QuoteState {}

class QuoteLoadedState extends QuoteState {
  DataModel resData;

  QuoteLoadedState({required this.resData});
}

class QuoteErrorState extends QuoteState {
  String errormsg;

  QuoteErrorState({required this.errormsg});
}

class DataModel {
  List<Quotes>? quotes;
  int? total;
  int? skip;
  int? limit;

  DataModel({this.quotes, this.total, this.skip, this.limit});

  DataModel.fromJson(Map<String, dynamic> json) {
    if (json['quotes'] != null) {
      quotes = <Quotes>[];
      json['quotes'].forEach((v) {
        quotes!.add(new Quotes.fromJson(v));
      });
    }
    total = json['total'];
    skip = json['skip'];
    limit = json['limit'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.quotes != null) {
      data['quotes'] = this.quotes!.map((v) => v.toJson()).toList();
    }
    data['total'] = this.total;
    data['skip'] = this.skip;
    data['limit'] = this.limit;
    return data;
  }
}

class Quotes {
  int? id;
  String? quote;
  String? author;

  Quotes({this.id, this.quote, this.author});

  Quotes.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    quote = json['quote'];
    author = json['author'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['quote'] = this.quote;
    data['author'] = this.author;
    return data;
  }
}