Question

亲爱的，我是flutter的新手，我想将来自flutter的发帖请求发送到服务器这是邮递员的请求

enter link description here

帖子标题：

键值

接受：application / json

Content-Type：应用程序/ x-www-form-urlencoded

后验证：

熊代币

帖子正文：

键：值

地址：地址

说明：说明

反馈：反馈

media：download.png

我想从颤抖中提出这个要求这是我的代码：

File _img; // taken by camera

Map<String,String> headers = {
        'Content-Type':'application/json',
        'Authorization': 'Bearer $token',
      };

 final msg = jsonEncode({
        "address"    : _address,
        "description": _description,
        "feedback"   : _techicalSupport,
        "media"      : _img;
       });


 try{
        var response = await http.post(
          "url",
          headers: headers,
          body: msg,
        );
        print("${response.toString()}");
   }catch(e){
        print("${e.toString()}");
    }

我收到此错误：未处理的异常：将对象转换为可编码对象失败：'_File'的实例

注意：不是必需的媒体，当我从主体中删除它时，它会在数据库中创建记录

我想在体内添加媒体。我该怎么办...

Answer 1

这是我的问题的答案，我使用了 Dio 库：

extractFeatures

Answer 2

您应使用MultipartRequest发送文件。

import 'dart:io';
import 'package:http/http.dart' as http;
import 'package:http_parser/http_parser.dart';
import 'package:image_picker/image_picker.dart';
import 'dart:convert';

void send() async {
  final msg = {
    "address": "test",
    "description": "test",
    "feedback": "test",
  };

  File _img;

  var image = await ImagePicker.pickImage(source: ImageSource.camera);

  _img = image;

  var response = await http.MultipartRequest(
      'POST', Uri.parse("url"))
    ..fields.addAll(msg)
    ..files.add(http.MultipartFile.fromBytes('image', _img.readAsBytesSync(),
        contentType: MediaType('image', 'jpeg'), filename: 'test.jpg'));


  print(response);
}

Answer 3

您需要将_img转换为MultipartFile

    MultipartFile file=MultipartFile.fromBytes(
        'media', await filePath.readAsBytes(),
        filename: 'FILE_NAME');

    var request = http.MultipartRequest("POST", Uri.parse(url));
    if (files != null) request.files.add(file);

Answer 4

1。配置FilePicker库（可选步骤，您可以使用任何库选择文件）

然后选择文件

File file = await FilePicker.getFile();

2。配置dio库，版本here

import 'package:dio/dio.dart';

然后

FormData formData = FormData.fromMap({
 "FIELD_NAME_WEBSERVICE_HERE": await MultipartFile.fromFile(imageFile.path,filename: "anyname_or_filename"),
"FIELD_NAME_WEBSERVICE_HERE":"sample value for another field"),
              });

    var response = await Dio().post("FULL_URL_HERE", data: formData);

    print(response);

向文件发送请求到服务器

4 个答案: