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dio

A powerful Http client for Dart, which supports Interceptors, Global configuration, FormData, Request Cancellation, File downloading, Timeout etc.

Get started

Add dependency

dependencies:
  dio: ^4.0.0

Already know Dio 3 and just want to learn about what's new in Dio 4? Check out the Migration Guide!

Super simple to use

import 'package:dio/dio.dart';
void getHttp() async {
  try {
    var response = await Dio().get('http://www.google.com');
    print(response);
  } catch (e) {
    print(e);
  }
}

awesome-dio

🎉 A curated list of awesome things related to dio.

Plugins (support 4.0)

| Plugins | Status | Description | | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | | diocookiemanager | | A cookie manager for Dio | | diohttp2adapter | | A Dio HttpClientAdapter which support Http/2.0 |

Related Projects

Welcome to submit Dio's third-party plugins and related libraries here .

Table of contents

• Examples

• Dio APIs

• Request Options

• Response Schema

• Interceptors

• Cookie Manager

• Handling Errors

• Using application/x-www-form-urlencoded format

• Sending FormData

• Transformer

• Set proxy and HttpClient config

• Https certificate verification

• HttpClientAdapter

• Cancellation

• Extends Dio class

• Http2 support

• Features and bugs

Examples

Performing a

GET

Response response;
var dio = Dio();
response = await dio.get('/test?id=12&name=wendu');
print(response.data.toString());
// Optionally the request above could also be done as
response = await dio.get('/test', queryParameters: {'id': 12, 'name': 'wendu'});
print(response.data.toString());

Performing a

POST

response = await dio.post('/test', data: {'id': 12, 'name': 'wendu'});

Performing multiple concurrent requests:

response = await Future.wait([dio.post('/info'), dio.get('/token')]);

Downloading a file:

response = await dio.download('https://www.google.com/', './xx.html');

Get response stream:

Response rs;
rs = await Dio().get(url,
  options: Options(responseType: ResponseType.stream),  // set responseType to `stream`
);
print(rs.data.stream); //response stream

Get response with bytes:

Response> rs 
rs = await Dio().get>(url,
 options: Options(responseType: ResponseType.bytes), // set responseType to `bytes`
);
print(rs.data); // List

Sending FormData:

var formData = FormData.fromMap({
  'name': 'wendux',
  'age': 25,
});
var response = await dio.post('/info', data: formData);

Uploading multiple files to server by FormData:

var formData = FormData.fromMap({
  'name': 'wendux',
  'age': 25,
  'file': await MultipartFile.fromFile('./text.txt', filename: 'upload.txt'),
  'files': [
    await MultipartFile.fromFile('./text1.txt', filename: 'text1.txt'),
    await MultipartFile.fromFile('./text2.txt', filename: 'text2.txt'),
  ]
});
var response = await dio.post('/info', data: formData);

Listening the uploading progress:

response = await dio.post(
  'http://www.dtworkroom.com/doris/1/2.0.0/test',
  data: {'aa': 'bb' * 22},
  onSendProgress: (int sent, int total) {
    print('$sent $total');
  },
);

Post binary data by Stream:

// Binary data
List postData = [...];
await dio.post(
  url,
  data: Stream.fromIterable(postData.map((e) => [e])), //create a Stream>
  options: Options(
    headers: {
      Headers.contentLengthHeader: postData.length, // set content-length
    },
  ),
);

…you can find all examples code here.

Dio APIs

Creating an instance and set default configs.

You can create instance of Dio with an optional

BaseOptions

var dio = Dio(); // with default Options

// Set default configs
dio.options.baseUrl = 'https://www.xx.com/api';
dio.options.connectTimeout = 5000; //5s
dio.options.receiveTimeout = 3000;
// or new Dio with a BaseOptions instance.
var options = BaseOptions(
  baseUrl: 'https://www.xx.com/api',
  connectTimeout: 5000,
  receiveTimeout: 3000,
);
Dio dio = Dio(options);

The core API in Dio instance is:

Future request(String path, {data,Map queryParameters, Options options,CancelToken cancelToken, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress)

response = await dio.request(
  '/test',
  data: {'id':12,'name':'xx'},
  options: Options(method:'GET'),
);

Request method aliases

For convenience aliases have been provided for all supported request methods.

Future get(...)

Future post(...)

Future put(...)

Future delete(...)

Future head(...)

Future put(...)

Future path(...)

Future download(...)

Future fetch(RequestOptions) new*

Request Options

The Options class describes the http request information and configuration. Each Dio instance has a base config for all requests maked by itself, and we can override the base config with [Options] when make a single request. The [BaseOptions] declaration as follows:

{
  /// Http method.
  String method;

  /// Request base url, it can contain sub path, like: 'https://www.google.com/api/'.
  String baseUrl;
  /// Http request headers.
  Map headers;
   /// Timeout in milliseconds for opening  url.
  int connectTimeout;
   ///  Whenever more than [receiveTimeout] (in milliseconds) passes between two events from response stream,
  ///  [Dio] will throw the [DioError] with [DioErrorType.RECEIVE_TIMEOUT].
  ///  Note: This is not the receiving time limitation.
  int receiveTimeout;
  /// Request data, can be any type.
  T data;
  /// If the path starts with 'http(s)', the baseURL will be ignored, otherwise,
  /// it will be combined and then resolved with the baseUrl.
  String path='';
  /// The request Content-Type. The default value is 'application/json; charset=utf-8'.
  /// If you want to encode request body with 'application/x-www-form-urlencoded',
  /// you can set [Headers.formUrlEncodedContentType], and [Dio]
  /// will automatically encode the request body.
  String contentType;
  /// [responseType] indicates the type of data that the server will respond with
  /// options which defined in [ResponseType] are JSON, STREAM, PLAIN.
  ///
  /// The default value is JSON, dio will parse response string to json object automatically
  /// when the content-type of response is 'application/json'.
  ///
  /// If you want to receive response data with binary bytes, for example,
  /// downloading a image, use STREAM.
  ///
  /// If you want to receive the response data with String, use PLAIN.
  ResponseType responseType;
  /// validateStatus defines whether the request is successful for a given
  /// HTTP response status code. If validateStatus returns true ,
  /// the request will be perceived as successful; otherwise, considered as failed.
  ValidateStatus validateStatus;
  /// Custom field that you can retrieve it later in [Interceptor]、[Transformer] and the   [Response] object.
  Map extra;
  /// Common query parameters
  Map*/ > queryParameters;  
   /// [collectionFormat] indicates the format of collection data in request
  /// options which defined in [CollectionFormat] are csv, ssv, tsv, pipes, multi,multiCompatible.
  /// The default value is multiCompatible
  late CollectionFormat collectionFormat;
}

There is a complete example here.

Response Schema

The response for a request contains the following information.

{
  /// Response body. may have been transformed, please refer to [ResponseType].
  T? data;
  /// Response headers.
  Headers headers;
  /// The corresponding request info.
  Options request;
  /// Http status code.
  int? statusCode;
  String? statusMessage;
  /// Whether redirect 
  bool? isRedirect;  
  /// redirect info    
  List redirects ;
  /// Returns the final real request uri (maybe redirect). 
  Uri realUri;    
  /// Custom field that you can retrieve it later in `then`.
  Map extra;
}

When request is succeed, you will receive the response as follows:

Response response = await dio.get('https://www.google.com');
print(response.data);
print(response.headers);
print(response.request);
print(response.statusCode);

Interceptors

For each dio instance, We can add one or more interceptors, by which we can intercept requests 、 responses and errors before they are handled by

then

catchError

dio.interceptors.add(InterceptorsWrapper(
    onRequest:(options, handler){
     // Do something before request is sent
     return handler.next(options); //continue
     // If you want to resolve the request with some custom data，
     // you can resolve a `Response` object eg: `handler.resolve(response)`.
     // If you want to reject the request with a error message,
     // you can reject a `DioError` object eg: `handler.reject(dioError)`
    },
    onResponse:(response,handler) {
     // Do something with response data
     return handler.next(response); // continue
     // If you want to reject the request with a error message,
     // you can reject a `DioError` object eg: `handler.reject(dioError)` 
    },
    onError: (DioError e, handler) {
     // Do something with response error
     return  handler.next(e);//continue
     // If you want to resolve the request with some custom data，
     // you can resolve a `Response` object eg: `handler.resolve(response)`.  
    }
));

Simple interceptor example:

import 'package:dio/dio.dart';
class CustomInterceptors extends Interceptor {
  @override
  void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
    print('REQUEST[${options.method}] => PATH: ${options.path}');
    return super.onRequest(options, handler);
  }
  @override
  Future onResponse(Response response, ResponseInterceptorHandler handler) {
    print('RESPONSE[${response.statusCode}] => PATH: ${response.request?.path}');
    return super.onResponse(response, handler);
  }
  @override
  Future onError(DioError err, ErrorInterceptorHandler handler) {
    print('ERROR[${err.response?.statusCode}] => PATH: ${err.request.path}');
    return super.onError(err, handler);
  }
}

Resolve and reject the request

In all interceptors, you can interfere with their execution flow. If you want to resolve the request/response with some custom data，you can call

handler.resolve(Response)

handler.reject(dioError)

dio.interceptors.add(InterceptorsWrapper(
  onRequest:(options, handler) {
   return handler.resolve(Response(requestOptions:options,data:'fake data'));
  },
));
Response response = await dio.get('/test');
print(response.data);//'fake data'

Lock/unlock the interceptors

You can lock/unlock the interceptors by calling their

lock()

unlock

tokenDio = Dio(); //Create a new instance to request the token.
tokenDio.options = dio.options.copyWith();
dio.interceptors.add(InterceptorsWrapper(
  onRequest:(Options options, handler){
    // If no token, request token firstly and lock this interceptor
    // to prevent other request enter this interceptor.
    dio.interceptors.requestLock.lock();
    // We use a new Dio(to avoid dead lock) instance to request token.
    tokenDio.get('/token').then((response){
       //Set the token to headers
       options.headers['token'] = response.data['data']['token'];
       handler.next(options); //continue
    }).catchError((error, stackTrace) {
       handler.reject(error, true);
    }).whenComplete(() => dio.interceptors.requestLock.unlock());
  }
));

You can clean the waiting queue by calling

clear()

aliases

When the request interceptor is locked, the incoming request will pause, this is equivalent to we locked the current dio instance, Therefore, Dio provied the two aliases for the

lock/unlock

dio.lock() == dio.interceptors.requestLock.lock()

dio.unlock() == dio.interceptors.requestLock.unlock()

dio.clear() == dio.interceptors.requestLock.clear()

Example

Because of security reasons, we need all the requests to set up a csrfToken in the header, if csrfToken does not exist, we need to request a csrfToken first, and then perform the network request, because the request csrfToken progress is asynchronous, so we need to execute this async request in request interceptor. The code is as follows:

dio.interceptors.add(InterceptorsWrapper(
  onRequest: (Options options, handler) async {
    print('send request：path:${options.path}，baseURL:${options.baseUrl}');
    if (csrfToken == null) {
      print('no token，request token firstly...');
      //lock the dio.
      dio.lock();
      tokenDio.get('/token').then((d) {
        options.headers['csrfToken'] = csrfToken = d.data['data']['token'];
        print('request token succeed, value: ' + d.data['data']['token']);
        print( 'continue to perform request：path:${options.path}，baseURL:${options.path}');
        handler.next(options);
      }).catchError((error, stackTrace) {
        handler.reject(error, true);
      }) .whenComplete(() => dio.unlock()); // unlock the dio
    } else {
      options.headers['csrfToken'] = csrfToken;
      handler.next(options);
    }
  }
));

For complete codes click here.

Log

You can set

LogInterceptor

dio.interceptors.add(LogInterceptor(responseBody: false)); //开启请求日志

Custom Interceptor

You can custom interceptor by extending the

Interceptor

Cookie Manager

diocookiemanager package is a cookie manager for Dio.

Handling Errors

When a error occurs, Dio will wrap the

Error/Exception

DioError

try {
  //404
  await dio.get('https://wendux.github.io/xsddddd');
} on DioError catch (e) {
  // The request was made and the server responded with a status code
  // that falls out of the range of 2xx and is also not 304.
  if (e.response) {
    print(e.response.data)
    print(e.response.headers)
    print(e.response.request)
  } else {
    // Something happened in setting up or sending the request that triggered an Error
    print(e.request)
    print(e.message)
  }
}

DioError scheme

 {
  /// Response info, it may be `null` if the request can't reach to
  /// the http server, for example, occurring a dns error, network is not available.
  Response? response;
  /// Request info.
  RequestOptions? request;
  /// Error descriptions.
  String message;

  DioErrorType type;
  /// The original error/exception object; It's usually not null when type
  /// is DioErrorType.DEFAULT
  dynamic? error;
}

DioErrorType

enum DioErrorType {
  /// It occurs when url is opened timeout.
  connectTimeout,

  /// It occurs when url is sent timeout.
  sendTimeout,
  ///It occurs when receiving timeout.
  receiveTimeout,
  /// When the server response, but with a incorrect status, such as 404, 503...
  response,
  /// When the request is cancelled, dio will throw a error with this type.
  cancel,
  /// Default error type, Some other Error. In this case, you can
  /// use the DioError.error if it is not null.
  other,
}

Using application/x-www-form-urlencoded format

By default, Dio serializes request data(except String type) to

JSON

application/x-www-form-urlencoded

//Instance level
dio.options.contentType= Headers.formUrlEncodedContentType;
//or works once
dio.post(
  '/info',
  data: {'id': 5},
  options: Options(contentType: Headers.formUrlEncodedContentType),
);

Sending FormData

You can also send FormData with Dio, which will send data in the

multipart/form-data

var formData = FormData.fromMap({
  'name': 'wendux',
  'age': 25,
  'file': await MultipartFile.fromFile('./text.txt',filename: 'upload.txt')
});
response = await dio.post('/info', data: formData);

There is a complete example here.

Multiple files upload

There are two ways to add multiple files to

FormData

FormData.fromMap({
  'files': [
    MultipartFile.fromFileSync('./example/upload.txt', filename: 'upload.txt'),
    MultipartFile.fromFileSync('./example/upload.txt', filename: 'upload.txt'),
  ]
});

The upload key eventually becomes 'files[]'，This is because many back-end services add a middle bracket to key when they get an array of files. If you don't want “[]”，you should create FormData as follows（Don't use

FormData.fromMap

var formData = FormData();
formData.files.addAll([
  MapEntry('files',
    MultipartFile.fromFileSync('./example/upload.txt',filename: 'upload.txt'),
  ),
  MapEntry('files',
    MultipartFile.fromFileSync('./example/upload.txt',filename: 'upload.txt'),
  ),
]);

Transformer

Transformer

DefaultTransformer

Transformer

Transformer

DefaultTransformer

dio.transformer

In flutter

If you use dio in flutter development, you'd better to decode json in background with [compute] function.

// Must be top-level function
_parseAndDecode(String response) {
  return jsonDecode(response);
}

parseJson(String text) {
  return compute(_parseAndDecode, text);
}
void main() {
  ...
  //Custom jsonDecodeCallback
  (dio.transformer as DefaultTransformer).jsonDecodeCallback = parseJson;
  runApp(MyApp());
}

Other Example

There is an example for customizing Transformer.

HttpClientAdapter

HttpClientAdapter is a bridge between Dio and HttpClient.

Dio implements standard and friendly API for developer.

HttpClient: It is the real object that makes Http requests.

We can use any HttpClient not just

dart:io:HttpClient

HttpClientAdapter

DefaultHttpClientAdapter

dio.httpClientAdapter = new DefaultHttpClientAdapter();

Here is a simple example to custom adapter.

Using proxy

DefaultHttpClientAdapter

dart:io:HttpClient

import 'package:dio/dio.dart';
import 'package:dio/adapter.dart';
...
(dio.httpClientAdapter as DefaultHttpClientAdapter).onHttpClientCreate = (client) {
  // config the http client
  client.findProxy = (uri) {
    //proxy all request to localhost:8888
    return 'PROXY localhost:8888';
  };
  // you can also create a new HttpClient to dio
  // return HttpClient();
};

There is a complete example here.

Https certificate verification

There are two ways to verify the https certificate. Suppose the certificate format is PEM, the code like:

String PEM='XXXXX'; // certificate content
(dio.httpClientAdapter as DefaultHttpClientAdapter).onHttpClientCreate  = (client) {
  client.badCertificateCallback=(X509Certificate cert, String host, int port){
    if(cert.pem==PEM){ // Verify the certificate
      return true;
    }
    return false;
  };
};

Another way is creating a

SecurityContext

HttpClient

(dio.httpClientAdapter as DefaultHttpClientAdapter).onHttpClientCreate  = (client) {
  SecurityContext sc = SecurityContext();
  //file is the path of certificate
  sc.setTrustedCertificates(file);
  HttpClient httpClient = HttpClient(context: sc);
  return httpClient;
};

In this way, the format of certificate must be PEM or PKCS12.

Http2 support

diohttp2adapter package is a Dio HttpClientAdapter which support Http/2.0 .

Cancellation

You can cancel a request using a cancel token. One token can be shared with multiple requests. When a token's

cancel

CancelToken token = CancelToken();
dio.get(url, cancelToken: token)
   .catchError((DioError err){
    if (CancelToken.isCancel(err)) {
      print('Request canceled! '+ err.message)
    }else{
      // handle error.
    }
   });
// cancel the requests with "cancelled" message.
token.cancel('cancelled');

There is a complete example here.

Extends Dio class

Dio

Dio

DioForNative

DioForBrowser

import 'package:dio/dio.dart';
import 'package:dio/native_imp.dart'; //If in browser, import 'package:dio/browser_imp.dart'

class Http extends DioForNative {
  Http([BaseOptions options]):super(options){
    // do something
  }
}

We can also implement our Dio client:

class MyDio with DioMixin implements Dio{
  // ...
}

Copyright & License

This open source project authorized by https://flutterchina.club , and the license is MIT.

Features and bugs

Please file feature requests and bugs at the issue tracker.

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