Dart：未处理的异常：类型'String'不是'index'类型'int'的子类型

Question

当我使用 ['name'] 从 json http 链接打印名称时，我收到此错误：

Unhandled exception:
type 'String' is not a subtype of type 'int' of 'index'

代码是：

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

void main() {
  print(getData());
}

Future<http.Response?> getData() {
  return http
      .get(Uri.parse("https://jsonplaceholder.typicode.com/users"))
      .then((http.Response response) {
    var a = jsonDecode(response.body)['name'];
    print(a);
  });
}

Answer 1

您的 JSON 响应采用列表格式。您需要从该列表中选择一个对象才能使用['name'] 选择器。

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

void main() {
  var response = getData();
  for (var person in reponse) {
    print(person['name']);
  }
}

Future<http.Response?> getData() {
  return http
      .get(Uri.parse("https://jsonplaceholder.typicode.com/users"))
      .then((http.Response response) {
    var a = jsonDecode(response.body);
    print(a);

    // Select one of the items here. This case we're selecting the first one.
    var name = a[0]['name'];
    print(name);

    return a;
  });
}