未处理的异常：FormatException：意外的输入结束（在字符 2 处）

Question

我想显示此页面的数据

但是当我点击贷款模拟按钮时，它显示这个错误

    E/flutter ( 4439): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: FormatException: Unexpected end of input (at character 2)
    E/flutter ( 4439): [
E/flutter ( 4439): #6      LoanModel.simulators (package:fluttermysql/LoanModel.dart:51:34)
E/flutter ( 4439): <asynchronous suspension>
E/flutter ( 4439): #7      _LoanSimulationState.result (package:fluttermysql/view/LoanSimulation.dart:30:5)
E/flutter ( 4439): <asynchronous suspension>

这是我的 LoanModel.Simulators

  static Future<LoanModel> simulators({String periodtime, String interestpermonth, String loanamountrequest, String idUser, String url}) async  {
    var url = "http://192.168.0.23/edufund-api/Api/loansimulation.php?periodtime=" + periodtime + "&interestpermonth=" + interestpermonth + "&loanamountrequest=" +loanamountrequest;
    final response = await http.get(url,headers:{"Content-Type":
    "application/json"});
    var res = LoanModel.fromJson(jsonDecode(response.body[0])); //without [0] it showing error Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'
    print(response.body);
    return res;
  }

这是贷款模拟的过程

void result() async {
    LoanModel loanModel;
    await LoanModel.simulators(
        periodtime: periodtime,
        interestpermonth: interestpermonth,
        loanamountrequest: loanamountrequest,
        url: BaseURL.kLoanSimulationUrl2)
        .then((value) => loanModel = value as LoanModel);
    print(loanModel.status);
    if (loanModel.status == true) {
      Navigator.pushReplacementNamed(context, Simulator.id);
    } else {
      _scaffoldKey.currentState.showSnackBar(SnackBar(
        content: Text(loanModel.message),
        duration: Duration(seconds: 3),
      ));
    }
  }

BaseURL的链接是http://192.168.0.23/edufund-api/Api/loansimulation.php（不带参数） 我想根据 Flutter Https Unhandled Exception: Invalid argument(s)

显示到列表视图

我得到的带有 [0] 的 response.body 是

[{"No":0,"interest":"0.00","balance":"10,000,000.00","principal":"0.00","Installment":"0.00","Status":true},{"No":1,"interest":"100,000.00","balance":"0.00","principal":"10,000,000.00","Installment":"10,100,000.00","Status":true}]

这是我的贷款模型

class LoanModel {
  int no;
  String interest;
  String balance;
  String principal;
  String installment;
  bool status;
  String message;

  LoanModel(
      {this.no,
        this.interest,
        this.balance,
        this.principal,
        this.installment,
        this.status,
      this.message});

  LoanModel.fromJson(Map<String, dynamic> json) {
    no = json['No'];
    interest = json['interest'];
    balance = json['balance'];
    principal = json['principal'];
    installment = json['Installment'];
    status = json['Status'];
    message = json['message'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['No'] = this.no;
    data['interest'] = this.interest;
    data['balance'] = this.balance;
    data['principal'] = this.principal;
    data['Installment'] = this.installment;
    data['Status'] = this.status;
    data['message'] = this.message;
    return data;
  }
}

如何修复该错误？没有解决办法。

Answer 1

代码中似乎有一些错误，我会指出，

static Future<LoanModel> simulators({String periodtime, String interestpermonth, String loanamountrequest, String idUser, String url}) async  {
  // This var url is a String
  var url = "http://192.168.0.23/edufund-api/Api/loansimulation.php?periodtime=" + periodtime + "&interestpermonth=" + interestpermonth + "&loanamountrequest=" +loanamountrequest;

  // Here you are using url directly, but http.get requires a Uri object
  // You have already specified the content-type here. so your response will be a jsonObject itself.
  final response = await http.get(url,headers:{"Content-Type": "application/json"});

  // Since your response is already a jsonObject, you don't need jsonDecode here, just use LoanModel.fromJson(response.body[0]);
  var res = LoanModel.fromJson(jsonDecode(response.body[0])); //without [0] it showing error Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'
  print(response.body);
  return res;
}

所以，主要问题应该是这条线，

var res = LoanModel.fromJson(jsonDecode(response.body[0]));

改成

var res = LoanModel.fromJson(response.body[0]);

由于您的 response.body 已经是 json object，所以您可以访问 response.body[0]。

另外，你说without [0] it showing error。这是因为您的 response.body 是 List 的 json object，即 List<Map<String, dynamic>。但是您的 LoadModel.fromJson 只需要一个 Map<String,dynamic> 而不是 List。 这就是为什么您必须使用 [0] 获取一个元素并将其传递给 fromJson。