小编Faz*_*rav的帖子

我是颤振新手。当我尝试将数据上传到服务器时，我遇到了一些问题，例如： 1.NoSuchMethodError：在 null 上调用 getter 'friendsList' 2.DioError [DioErrorType.DEFAULT]：将对象转换为可编码对象失败：'FormData' 实例

import 'dart:convert';
import 'dart:io';

import 'package:data_collection/helperClass/testForAddButton.dart';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:http_parser/http_parser.dart';

class AutoCompleteDemo extends StatefulWidget {
  @override
  _AutoCompleteDemoState createState() => _AutoCompleteDemoState();
}

class _AutoCompleteDemoState extends State<AutoCompleteDemo> {
  final hospitalNameEng = TextEditingController();
  final _serviceKey = GlobalKey<FormState>();
  static List<String> friendsList = [];
  File imageFile;
  String servicejson;
  bool loading = true;

  @override
  void initState() {
    super.initState();
  }

  //for camera dialogBox
  Future<void> _showChoiceDialog(BuildContext context) {
    return showDialog(
        context: context,
        builder: (BuildContext context) …