向本地服务器发送请求时出现 Flutter Web XMLHttpRequest 错误

Posted 2023-02-23

【中文标题】向本地服务器发送请求时出现 Flutter Web XMLHttpRequest 错误

【英文标题】：Flutter Web XMLHttpRequest error on sending request to local server

【发布时间】：2022-01-13 15:29:47

【问题描述】：

我正在使用以下代码在 Flutter Web Debug 模式下向本地后端服务器发送请求：

final response = await http.post(
          Uri.parse('http://localhost/api/user/login'),
          body: convert.jsonEncode(loginRequestBody),
          headers: 'content-type': 'application/json');

它在移动设备上运行良好，但在网络上显示此错误

XMLHttpRequest error.
Error: Failed assertion: boolean expression must not be null
    at Object.throw_ [as throw] (http://localhost:58442/dart_sdk.js:5374:11)
    at Object.test (http://localhost:58442/dart_sdk.js:5666:32)
    at login_user_data.LogInUserData.new.<anonymous> (http://localhost:58442/packages/tumblrx/screens/login_user_data.dart.lib.js:241:93)
    at Generator.next (<anonymous>)
    at http://localhost:58442/dart_sdk.js:40646:33
    at _RootZone.runUnary (http://localhost:58442/dart_sdk.js:40503:58)
    at _FutureListener.thenAwait.handleValue (http://localhost:58442/dart_sdk.js:35432:29)
    at handleValueCallback (http://localhost:58442/dart_sdk.js:36017:49)
    at Function._propagateToListeners (http://localhost:58442/dart_sdk.js:36055:17)
    at _Future.new.[_completeError] (http://localhost:58442/dart_sdk.js:35905:23)
    at async._AsyncCallbackEntry.new.callback (http://localhost:58442/dart_sdk.js:35944:31)
    at Object._microtaskLoop (http://localhost:58442/dart_sdk.js:40808:13)
    at _startMicrotaskLoop (http://localhost:58442/dart_sdk.js:40814:13)
    at http://localhost:58442/dart_sdk.js:36279:9

我该如何解决？

【问题讨论】：

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【参考方案1】：

您是否使用任何模型来解析响应？您最有可能正在等待未存储在后端响应中的布尔字段。但我不确定我是否知道它在移动设备上运行的原因