import 'package:dio/dio.dart';
import 'package:json_annotation/json_annotation.dart';
import 'package:retrofit/retrofit.dart';
part 'example.g.dart';
@RestApi(baseUrl: "https://5d42a6e2bc64f90014a56ca0.mockapi.io/api/v1/")
abstract class RestClient {
  factory RestClient(Dio dio, {String baseUrl}) = _RestClient;
  @GET("/tasks/{id}")
  Future<Task> getTask(@Path("id") String id);
  @GET('/demo')
  Future<String> queries(@Queries() Map<String, dynamic> queries);
  @GET("https://httpbin.org/get")
  Future<String> namedExample(@Query("apikey") String apiKey, @Query("scope") String scope, @Query("type") String type, @Query("from") int from);
  @PATCH("/tasks/{id}")
  Future<Task> updateTaskPart(@Path() String id, @Body() Map<String, dynamic> map);
  @PUT("/tasks/{id}")
  Future<Task> updateTask(@Path() String id, @Body() Task task);
  @DELETE("/tasks/{id}")
  Future<void> deleteTask(@Path() String id);
  @POST("/tasks")
  Future<Task> createTask(@Body() Task task);
  @POST("http://httpbin.org/post")
  Future<void> createNewTaskFromFile(@Part() File file);
  @POST("http://httpbin.org/post")
  @FormUrlEncoded()
  Future<String> postUrlEncodedFormData(@Field() String hello);
}
@JsonSerializable()
class Task {
  String id;
  String name;
  String avatar;
  String createdAt;
  Task({this.id, this.name, this.avatar, this.createdAt});
  factory Task.fromJson(Map<String, dynamic> json) => _$TaskFromJson(json);
  Map<String, dynamic> toJson() => _$TaskToJson(this);
}

import 'package:logger/logger.dart';
import 'package:retrofit_example/example.dart';
import 'package:dio/dio.dart';
final logger = Logger();
void main(List<String> args) {
  final dio = Dio(); // Provide a dio instance
  dio.options.headers["Demo-Header"] = "demo header";
  final client = RestClient(dio);
  client.getTasks().then((it) => logger.i(it));
}

openapi-generator-cli generate -i https://petstore.swagger.io/v2/swagger.json -g dart-dio -o .pet_api --additional-properties pubName=pet_api

{
  "$schema": "node_modules/@openapitools/openapi-generator-cli/config.schema.json",
  "spaces": 2,
  "generator-cli": {
    "version": "5.1.1",
    "generators": {
      "pet": {
        "input-spec": "https://petstore.swagger.io/v2/swagger.json",
        "generator-name": "dart-dio",
        "output": ".pet_api",
        "additionalProperties": {
          "pubName": "pet_api"
        }
      }
    }
  }
}

openapi-generator-cli generate

# <generator-name>, dart-dio - for example
openapi-generator-cli config-help -g dart-dio

flutter: Deserializing '[id, 9, category, {id: 0, name: cats}, photoUrls, [string], tags, [{id: 0, na...' to 'Pet' failed due to: Tried to construct class "Pet" with null field "name". This is forbidden; to allow it, mark "name" with @nullable.

{
  "Pet": {
    "type": "object",
    "required": [
      "name", // <- required field
      "photoUrls" // <- and this too
    ],
    "properties": {
      "id": {
        "type": "integer",
        "format": "int64"
      },
      "category": {
        "$ref": "#/definitions/Category"
      },
      "name": {
        "type": "string",
        "example": "doggie"
      },
      "photoUrls": {
        "type": "array",
        "xml": {
          "wrapped": true
        },
        "items": {
          "type": "string",
          "xml": {
            "name": "photoUrl"
          }
        }
      },
      "tags": {
        "type": "array",
        "xml": {
          "wrapped": true
        },
        "items": {
          "xml": {
            "name": "tag"
          },
          "$ref": "#/definitions/Tag"
        }
      },
      "status": {
        "type": "string",
        "description": "pet status in the store",
        "enum": [
          "available",
          "pending",
          "sold"
        ]
      }
    },
    "xml": {
      "name": "Pet"
    }
  },
  "Category": {
    "type": "object",
    "properties": {
      "id": {
        "type": "integer",
        "format": "int64"
      },
      "name": {
        "type": "string"
      }
    },
    "xml": {
      "name": "Category"
    }
  },
  "Tag": {
    "type": "object",
    "properties": {
      "id": {
        "type": "integer",
        "format": "int64"
      },
      "name": {
        "type": "string"
      }
    },
    "xml": {
      "name": "Tag"
    }
  }
}

cd .pet_api
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs

name: openapi_sample
description: Sample for OpenAPI
version: 1.0.0
publish_to: none
environment:
  flutter: ">=2.0.0"
  sdk: ">=2.12.0 <3.0.0"
dependencies:
  flutter:
    sdk: flutter
  pet_api: # <- our generated library
    path: .pet_api

import 'package:dio/dio.dart';
import 'package:pet_api/api/pet_api.dart';
import 'package:pet_api/model/pet.dart';
import 'package:pet_api/serializers.dart'; // <- we must use [standartSerializers] from this package module
Future<Pet> loadPet() async {
  final Dio dio = Dio(BaseOptions(baseUrl: 'https://petstore.swagger.io/v2'));
  final PetApi petApi = PetApi(dio, standardSerializers);
  const petId = 9;
  final Response<Pet> response = await petApi.getPetById(petId, headers: <String, String>{'Authorization': 'Bearer special-key'});
  return response.data;
}

name: pet_api
version: 1.0.0
description: OpenAPI API client
environment:
  sdk: '>=2.7.0 <3.0.0' # -> '>=2.12.0 <3.0.0'
dependencies:
  dio: '^3.0.9' # Actual -> 4.0.0
  built_value: '>=7.1.0 <8.0.0' # -> 8.1.0
  built_collection: '>=4.3.2 <5.0.0' # -> 5.1.0
dev_dependencies:
  built_value_generator: '>=7.1.0 <8.0.0' # -> 8.1.0
  build_runner: any # -> 2.0.5
  test: '>=1.3.0 <1.16.0' # -> 1.17.9

openapi-generator-cli generate
cd .pet_api || exit
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs

openapi-generator-cli generate
cd .pet_api || exit
echo "name: pet_api
version: 1.0.0
description: OpenAPI API client
environment:
sdk: '>=2.12.0 <3.0.0'
dependencies:
dio: ^4.0.0 built_value: ^8.1.0 built_collection: ^5.1.0
dev_dependencies:
built_value_generator: ^8.1.0 build_runner: ^2.0.5 test: ^1.17.9" > pubspec.yaml
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs

//
// AUTO-GENERATED FILE, DO NOT MODIFY!
//
// @dart=2.7  <--
// ignore_for_file: unused_import

const fs = require('fs');
const p = require('path');
const dartFiles = [];
function main() {
  const openapiDirPath = p.resolve(__dirname, '.pet_api');
  searchDartFiles(openapiDirPath);
  for (const filePath of dartFiles) {
    fixFile(filePath);
    console.log('Fixed file:', filePath);
  }
}
function searchDartFiles(path) {
  const isDir = fs.lstatSync(path).isDirectory();
  if (isDir) {
    const dirContent = fs.readdirSync(path);
    for (const dirContentPath of dirContent) {
      const fullPath = p.resolve(path, dirContentPath);
      searchDartFiles(fullPath);
    }
  } else {
    if (path.includes('.dart')) {
      dartFiles.push(path);
    }
  }
}
function fixFile(path) {
  const fileContent = fs.readFileSync(path).toString();
  const fixedContent = fixOthers(fileContent);
  fs.writeFileSync(path, fixedContent);
}
const fixOthers = fileContent => {
  let content = fileContent;
  for (const entry of otherFixers.entries()) {
    content = content.replace(entry[0], entry[1]);
  }
  return content;
};
const otherFixers = new Map([
  // ? Base fixers for Dio and standard params
  [
    '// @dart=2.7',
    '// ',
  ],
  [
    /response\.request/gm,
    'response.requestOptions',
  ],
  [
    /request: /gm,
    'requestOptions: ',
  ],
  [
    /Iterable<Object> serialized/gm,
    'Iterable<Object?> serialized',
  ],
  [
    /(?<type>^ +Uint8List)(?<value> file,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +String)(?<value> additionalMetadata,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +ProgressCallback)(?<value> onReceiveProgress,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +ProgressCallback)(?<value> onSendProgress,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +ValidateStatus)(?<value> validateStatus,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +Map<String, dynamic>)(?<value> extra,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +Map<String, dynamic>)(?<value> headers,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +CancelToken)(?<value> cancelToken,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(@nullable\n)(?<annotation>^ +@.*\n)(?<type>.*)(?<getter> get )(?<variable>.*\n)/gm,
    '$<annotation>$<spaces>$<type>?$<getter>$<variable>',
  ],
  [
    'final result = <Object>[];',
    'final result = <Object?>[];',
  ],
  [
    'Iterable<Object> serialize',
    'Iterable<Object?> serialize',
  ],
  [
    /^ *final _response = await _dio.request<dynamic>\(\n +_request\.path,\n +data: _bodyData,\n +options: _request,\n +\);/gm,
    `_request.data = _bodyData;
    final _response = await _dio.fetch<dynamic>(_request);
    `,
  ],
  // ? Special, custom params for concrete API
  [
    /(?<type>^ +String)(?<value> apiKey,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +String)(?<value> name,)/gm,
    '$<type>?$<value>',
  ],
  [
    /(?<type>^ +String)(?<value> status,)/gm,
    '$<type>?$<value>',
  ],
]);
main();

rm -rf ".pet_api" || echo ".pet_api folder not found"
openapi-generator-cli generate
cd .pet_api || exit
echo "name: pet_api
version: 1.0.0
description: OpenAPI API client
environment:
  sdk: '>=2.12.0 <3.0.0'
dependencies:
  dio: ^4.0.0
  built_value: ^8.1.0
  built_collection: ^5.1.0
dev_dependencies:
  built_value_generator: ^8.1.0
  build_runner: ^2.0.5
  test: ^1.17.9
" > pubspec.yaml
node ../openapi_updater.js # <--
flutter pub get
flutter pub run build_runner build --delete-conflicting-outputs