颤振 http 标头答案

【问题标题】：Flutter http headers颤振 http 标头
【发布时间】：2019-04-17 08:59:48
【问题描述】：

post 请求在设置标头映射时抛出错误。

这是我的代码

Future<GenericResponse> makePostCall(
  GenericRequest genericRequest) {String URL = "$BASE_URL/api/";

Map data = {
  "name": "name",
  "email": "email",
  "mobile": "mobile",
  "transportationRequired": false,
  "userId": 5,
};

Map userHeader = {"Content-type": "application/json", "Accept": "application/json"};


return _netUtil.post(URL, body: data, headers:userHeader).then((dynamic res) {
  print(res);
  if (res["code"] != 200) throw new Exception(res["message"][0]);
  return GenericResponse.fromJson(res);
});

}

但我在标题中遇到了这个异常。

══╡ EXCEPTION CAUGHT BY GESTURE ╞═
flutter: The following assertion was thrown while handling a gesture:
flutter: type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Map<String, String>'
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new?template=BUG.md
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0      NetworkUtil.post1 (package:saranam/network/network_util.dart:50:41)
flutter: #1      RestDatasource.bookPandit (package:saranam/network/rest_data_source.dart:204:21)

有人遇到这个问题吗？上面的日志我没有找到任何线索。

【问题讨论】：

尝试将你的 body 编码为 json，例如 var body = json.encode({"foo": "bar"});

标签： http dart http-headers flutter

【解决方案1】：

试试

 Map<String, String> requestHeaders = {
       'Content-type': 'application/json',
       'Accept': 'application/json',
       'Authorization': '<Your token>'
     };

【讨论】：

谢谢@Sami Kanafani，它部分解决了我的问题。
为什么是部分，你目前的问题是什么？
如果我们想将令牌传递给标头怎么办............我们将不胜感激
@SamiKanafani - 谢谢这解决了我的问题。不过问题是，如果没有<String, String>，我的代码似乎完成了，没有进行 REST 调用——我没有得到任何异常（与上面的示例不同），也没有 REST 响应（好或坏）。导致这种情况的幕后原因是什么？
我不太明白，你的意思是你删除了<String,String>，你没有例外但请求没有发送？

【解决方案2】：

你可以试试这个：

Map<String, String> get headers => {
        "Content-Type": "application/json",
        "Accept": "application/json",
        "Authorization": "Bearer $_token",
      };

然后连同您对标头的 http 请求一起将标头作为标头传递

示例：

Future<AvatarResponse> getAvatar() async {
    var url = "$urlPrefix/api/v1/a/me/avatar";
    print("fetching $url");
    var response = await http.get(url, headers: headers);
    if (response.statusCode != 200) {
      throw Exception(
          "Request to $url failed with status ${response.statusCode}: ${response.body}");
    }

    var avatar = AvatarResponse()
      ..mergeFromProto3Json(json.decode(response.body),
          ignoreUnknownFields: true);
    print(avatar);
    return avatar;
  }

【讨论】：

【解决方案3】：

我已经通过这种方式在标题中传递了一个私钥。这也将回答@Jaward：

class URLS {
    static const String BASE_URL = 'https://location.to.your/api';
    static const String USERNAME = 'myusername';
    static const String PASSWORD = 'mypassword';
}

在同一个 .dart 文件中：

class ApiService {

    Future<UserInfo> getUserInfo() async {

      var headers = {
        'pk': 'here_a_private_key',
        'authorization': 'Basic ' +
           base64Encode(utf8.encode('${URLS.USERNAME}:${URLS.PASSWORD}')),
        "Accept": "application/json"
      };

      final response = await http.get('${URLS.BASE_URL}/UserInfo/v1/GetUserInfo',
        headers: headers);

      if (response.statusCode == 200) {
        final jsonResponse = json.decode(response.body);
        return new UserInfo.fromJson(jsonResponse);
      } else {
        throw Exception('Failed to load data!');
      }
    }
}

【讨论】：

【解决方案4】：

试试这个

Future<String> createPost(String url, Map newPost) async {
  String collection;
  try{
    Map<String, String> headers = {"Content-type": "application/json"};
    Response response =
    await post(url, headers: headers, body: json.encode(newPost));
    String responsebody = response.body;
    final int statusCode = response.statusCode;
    if (statusCode == 200 || statusCode == 201) {
      final jsonResponse = json.decode(responsebody);
      collection = jsonResponse["token"];
    } 
    return collection;
  }
  catch(e){
    print("catch");
  }

}

【讨论】：

【解决方案5】：

Future<String> loginApi(String url) async {


 Map<String, String> header = new Map();
 header["content-type"] =  "application/x-www-form-urlencoded";  
header["token"] =  "token from device";  

try {
   final response = await http.post("$url",body:{
         "email":"test@test.com",
       "password":"3efeyrett"
       },headers: header);    

   Map<String,dynamic> output = jsonDecode(response.body);

        if (output["status"] == 200) {

           return "success";
        }else{
        return "error";

  } catch (e) {
    print("catch--------$e");
  return "error";
   }
return "";

}

【讨论】：

【解决方案6】：

 void getApi() async {
SharedPreferences prefsss = await SharedPreferences.getInstance();
String tokennn = prefsss.get("k_token");
String url = 'http://yourhost.com/services/Default/Places/List';
Map<String, String> mainheader = {
  "Content-type": "application/json",
  "Cookie": tokennn
};
String requestBody =
    '{"Take":100,"IncludeColumns":["Id","Name","Address","PhoneNumber","WebSite","Username","ImagePath","ServiceName","ZoneID","GalleryImages","Distance","ServiceTypeID"],"EqualityFilter":{"ServiceID":${_radioValue2 != null ? _radioValue2 : '""'},"ZoneID":"","Latitude":"${fav_lat != null ? fav_lat : 0.0}","Longitude":"${fav_long != null ? fav_long : 0.0}","SearchDistance":"${distanceZone}"},"ContainsText":"${_txtSearch}"}';

Response response = await post(url , headers: mainheader ,body:requestBody);
String parsedata = response.body;
var data = jsonDecode(parsedata);
var getval = data['Entities'] as List;
setState(() {
  list = getval.map<Entities>((json) => Entities.fromJson(json)).toList();
});
}

【讨论】：