我使用flutter http包创建了简单的发布请求。但是发送请求时我遇到了错误。
E/flutter ( 9479): [ERROR:flutter/shell/common/shell.cc(181)] Dart Error: Unhandled exception:
E/flutter ( 9479): type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Map<String, String>'
E/flutter ( 9479): #0 ApiRequester.sendLoginRequest (package:fitness_lanka/api_requester.dart:56:16)
E/flutter ( 9479): <asynchronous suspension>
E/flutter ( 9479): #1 LoginWidgets.buildLoginButton.<anonymous closure> (package:fitness_lanka/widgets/login_widgets.dart:82:62)
E/flutter ( 9479): #2 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
E/flutter ( 9479): #3 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
E/flutter ( 9479): #4 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter ( 9479): #5 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter ( 9479): #6 TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
E/flutter ( 9479): #7 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
E/flutter ( 9479): #8 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
E/flutter ( 9479): #9 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
E/flutter ( 9479): #10 _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:143:19)
E/flutter ( 9479): #11 _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
E/flutter ( 9479): #12 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
E/flutter ( 9479): #13 _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
E/flutter ( 9479): #14 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
E/flutter ( 9479): #15 _invoke1 (dart:ui/hooks.dart:153:13)
E/flutter ( 9479): #16 _dispatchPointerDataPacket (dart:ui/hooks.dart:107:5)
下面是我用来发送帖子请求的功能。
static Future<LoginData> sendLoginRequest(
String email, String password) async {
var headers = {'Accept': 'application/json'};
var body = {
'email': email,
'password': password,
};
http.Response response = await http.post(
"https://fitness-lanka-laravel.herokuapp.com/api/user/login",
headers: headers,
body: body,
);
return LoginData.fromResponse(response);
}
我将flutter从v0.8.2升级到v0.9.4。在将flutter升级到最新版本之前，它运行良好。
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel beta, v0.9.4, on Microsoft Windows [Version 10.0.17134.345], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK 28.0.2)
[√] Android Studio (version 3.2)
[√] IntelliJ IDEA Community Edition (version 2018.2)
[√] VS Code (version 1.28.1)
[√] Connected devices (1 available)
• No issues found!
-----更新-----
我将flutter降级到v0.8.2。现在我遇到了另一个错误。
E/flutter (24516): [ERROR:flutter/shell/common/shell.cc(181)] Dart Error: Unhandled exception:
E/flutter (24516): NoSuchMethodError: The getter 'length' was called on null.
E/flutter (24516): Receiver: null
E/flutter (24516): Tried calling: length
E/flutter (24516): #0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:48:5)
E/flutter (24516): #1 _Uri._uriEncode (dart:core/runtime/liburi_patch.dart:44:23)
E/flutter (24516): #2 Uri.encodeQueryComponent (dart:core/uri.dart:1092:17)
E/flutter (24516): #3 mapToQuery.<anonymous closure> (package:http/src/utils.dart:19:22)
E/flutter (24516): #4 CastMap.forEach.<anonymous closure> (dart:_internal/cast.dart:286:8)
E/flutter (24516): #5 __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/libcompact_hash.dart:365:8)
E/flutter (24516): #6 CastMap.forEach (dart:_internal/cast.dart:285:13)
E/flutter (24516): #7 mapToQuery (package:http/src/utils.dart:17:7)
E/flutter (24516): #8 Request.bodyFields= (package:http/src/request.dart:128:17)
E/flutter (24516): #9 BaseClient._sendUnstreamed (package:http/src/base_client.dart:165:17)
E/flutter (24516): <asynchronous suspension>
E/flutter (24516): #10 BaseClient.post (package:http/src/base_client.dart:56:5)
E/flutter (24516): #11 post.<anonymous closure> (package:http/http.dart:70:34)
E/flutter (24516): #12 _withClient (package:http/http.dart:167:20)
E/flutter (24516): <asynchronous suspension>
E/flutter (24516): #13 post (package:http/http.dart:70:3)
E/flutter (24516): #14 ApiRequester.sendLoginRequest (package:fitness_lanka/api_requester.dart:55:36)
E/flutter (24516): <asynchronous suspension>
E/flutter (24516): #15 LoginWidgets.buildLoginButton.<anonymous closure> (package:fitness_lanka/widgets/login_widgets.dart:84:62)
E/flutter (24516): #16 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:503:14)
E/flutter (24516): #17 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:558:30)
E/flutter (24516): #18 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter (24516): #19 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter (24516): #20 TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
E/flutter (24516): #21 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
E/flutter (24516): #22 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
E/flutter (24516): #23 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
E/flutter (24516): #24 _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:143:19)
E/flutter (24516): #25 _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
E/flutter (24516): #26 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
E/flutter (24516): #27 _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
E/flutter (24516): #28 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
E/flutter (24516): #29 _invoke1 (dart:ui/hooks.dart:142:13)
E/flutter (24516): #30 _dispatchPointerDataPacket (dart:ui/hooks.dart:99:5)
答案 0 :(得分：2)
以下代码对我有用：）
static Future<LoginData> sendLoginRequest(
String email, String password) async {
// Encode the string [uri] using percent-encoding to make it
// safe for literal use as a full URI.
String url = Uri.encodeFull('https://fitness-lanka-laravel.herokuapp.com/api/user/login');
// headers should be a subtype of Map<String, String>
Map<String, String> headers = {
"Accept": "application/json",
"Content-Type": "application/json",
};
// convert body to a JSON string
String body = json.encode(
{
'email': email,
'password': password,
},
);
// now it's safe to send the request
http.Response response = await http.post(
url,
body: body,
headers: headers,
);
return LoginData.fromResponse(response);
}
如果有人在json.encode(body)遇到错误
请添加以下项的导入：import 'dart:convert';