Question

我正在尝试从Postgres数据库获取数据，它在调试模式下不断抛出错误。尝试了许多解决方案，例如通过仿真器代理连接，它显示成功，但在仿真器设备上会引发错误。尝试了很多解决方案，包括曾经在该平台上发布过的解决方案。如果有人可以帮助我，我会很高兴。

      home: FutureBuilder(
        future: getUser(), // a previously-obtained Future<String> or null
        builder: (BuildContext context, AsyncSnapshot snapshot) {
          if (snapshot.connectionState == ConnectionState.none && snapshot.hasData == null) {
            //print('project snapshot data is: ${projectSnap.data}')
            return Container();
          }
          return ListView.builder(
            itemCount: snapshot.data.length,
            itemBuilder: (context, index) {
              return Column(
                children: <Widget>[

                ],
              );
            },
          );  
        },
      ),

  Future getUser() async {
    var result = await http.get(Uri.encodeFull('http://127.0.0.1:5000/api/register'), headers: {"Accept": "application/json"});
    print(result.body);
    return result;
  }

此错误也已记录在控制台上

I/flutter (18791): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (18791): The following NoSuchMethodError was thrown building FutureBuilder<dynamic>(dirty, state:
I/flutter (18791): _FutureBuilderState<dynamic>#96150):
I/flutter (18791): The getter 'length' was called on null.
I/flutter (18791): Receiver: null
I/flutter (18791): Tried calling: length
I/flutter (18791):
I/flutter (18791): The relevant error-causing widget was:
I/flutter (18791):   FutureBuilder<dynamic>
I/flutter (18791):   file:///C:/Users/Oregs/AndroidStudioProjects/TodoProject/App/todoapp/lib/main.dart:24:13
I/flutter (18791):
I/flutter (18791): When the exception was thrown, this was the stack:
I/flutter (18791): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
I/flutter (18791): #1      MyApp.build.<anonymous closure> (package:com/main.dart:32:38)
I/flutter (18791): #2      _FutureBuilderState.build (package:flutter/src/widgets/async.dart:732:55)
I/flutter (18791): #3      StatefulElement.build (package:flutter/src/widgets/framework.dart:4619:28)
I/flutter (18791): #4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4502:15)
I/flutter (18791): #5      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
I/flutter (18791): #6      Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
I/flutter (18791): #7      ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4481:5)
I/flutter (18791): #8      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4666:11)
I/flutter (18791): #9      ComponentElement.mount (package:flutter/src/widgets/framework.dart:4476:5)
I/flutter (18791): ...     Normal element mounting (115 frames)
I/flutter (18791): #124    Element.inflateWidget (package:flutter/src/widgets/framework.dart:3446:14)
I/flutter (18791): #125    MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5947:32)
I/flutter (18791): ...     Normal element mounting (238 frames)
I/flutter (18791): #363    Element.inflateWidget (package:flutter/src/widgets/framework.dart:3446:14)
I/flutter (18791): #364    Element.updateChild (package:flutter/src/widgets/framework.dart:3214:18)
I/flutter (18791): #365    RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1148:16)
I/flutter (18791): #366    RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1119:5)
I/flutter (18791): #367    RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:1061:17)
I/flutter (18791): #368    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2607:19)
I/flutter (18791): #369    RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1060:13)
I/flutter (18791): #370    WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:941:7)
I/flutter (18791): #371    WidgetsBinding.scheduleAttachRootWidget.<anonymous closure> (package:flutter/src/widgets/binding.dart:922:7)
I/flutter (18791): (elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
I/flutter (18791):
I/flutter (18791): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (18791): Another exception was thrown: NoSuchMethodError: The getter 'length' was called on null.

Flutter-> Flask SocketException（SocketException：操作系统错误：连接被拒绝，errno = 111，地址= 127.0.0.1，端口= 50484）

0 个答案: