我无法创建包含其他贴图的贴图

Question

我试图创建一个注册模型，并将其发送到我的API，但位置键有另一个地图/json对象，其中包含类型：点和坐标：[双，双]。

最后一个json对象应该是这样的

{
    "name": "Arsh Bansal",
    "email": "[e-mail]",
    "password": "123456789",
    "birthday": "06-21-2000",
    "gender": "Male",
    "location": {
        "type": "Point", 
        "coordinates": [13.0987, 88.403]
    },
    "phone_number": "123456789"
}

网络助手代码如下：

import 'package:http/http.dart' as http;
import 'dart:convert';

class NetworkHelper {

  NetworkHelper(this.url);
  NetworkHelper.withHeader(this.url, this.headers);

  final String url;
  Map<String, String> headers;

  Future getData() async {

    http.Response response = await http.get(url);

    if(response.statusCode == 200) {
      String data = response.body;

      return jsonDecode(data);
    } else {
      String error = response.body;

    }
  }

  Future<http.Response> postData(Map body) async {

    http.Response response = await http.post(url, headers: headers, body: body);
    return response;

  }

}

但我得到下面的错误

我得到的错误是：未处理的异常：类型“\u InternalLinkedHashMap”

#0      CastMap.forEach.<anonymous closure> (dart:_internal/cast.dart:288:25)
#1      _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8)
#2      CastMap.forEach (dart:_internal/cast.dart:287:13)
#3      mapToQuery (package:http/src/utils.dart:17:7)
#4      Request.bodyFields= (package:http/src/request.dart:137:12)
#5      BaseClient._sendUnstreamed (package:http/src/base_client.dart:170:17)
#6      BaseClient.post (package:http/src/base_client.dart:58:7)
#7      post.<anonymous closure> (package:http/http.dart:70:16)
#8      _withClient (package:http/http.dart:166:20)
#9      post (package:http/http.dart:69:5)
#10     NetworkHelper.postData (package:clubinn/services/network_helper.dart:28:36)
#11     Models.createUser (package:clubinn/models/models.dart:72:50)
#12     _SignUpPageState.build.<anonymous closure> (package:clubinn/sc<…>

Answer 1

您的问题是使用http。post和正文参数。如果您阅读了文档，可以看到文档描述如下：

body设置请求的主体。它可以是字符串、列表或映射。如果是字符串，则使用编码对其进行编码，并将其用作请求的主体。请求的内容类型默认为“text/plain”。

...

若body是一个映射，那个么使用编码将其编码为表单字段。请求的内容类型将设置为“application/x-www-form-urlencoded”；这不能被覆盖。

https://pub.dev/documentation/http/latest/http/post.html

输入的body来自以下代码：

    Map<String, dynamic> body = {
      "name": name,
      "email": email,
      "password": password,
      "birthday": DOB,
      "gender": gender,
      "location": location.toJson(),
      "phone_number": mobile
    };

其中类型甚至不接近于Map

  Map<String,dynamic> toJson() => {
    "type": type,
    "coordinates": List<double>.from(coordinates.map((x) => x)),
  };

另外，我不认为你想把地图放在首位。正如您在前面提到的留档中看到的，映射被“使用编码编码为表单字段”。相反，您真正想要的是将映射解析成JSON字符串，并将该字符串作为主体提供给http.post。

所以它应该是这样的：

http.Response response = await http.post(url, headers: headers, body: json.encode(body));