【问题标题】:Obtaining value from textfield and inserting into API url从文本字段中获取值并插入 API url
【发布时间】:2022-01-19 16:21:18
【问题描述】:

我添加了一个带有 TextEditingController 的文本字段

class _MyAppState extends State<MyApp> {
  late Future<Album> futureAlbum;
  late TextEditingController nummerpladeController = new TextEditingController();


  @override
  void initState() {
    super.initState();
    futureAlbum = fetchAlbum();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Fetch Data Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Fetch Data Example'),
        ),
        body:
        Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            children: [
              TextField(
                controller: nummerpladeController,
                onChanged: (str) {
                  setState(() {
                    str = nummerpladeController.text;
                  });
                },
              ),
              Center(
                child: FutureBuilder<Album>(
                  future: futureAlbum,
                  builder: (context, snapshot) {
                    if (snapshot.hasData) {
                      return new Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        crossAxisAlignment: CrossAxisAlignment.center,
                        children: [
                          Text("Registreringsnummer: ""${snapshot.data!.registration_number}"),
                          Text("Status: " "${snapshot.data!.status}"),
                          Text("Type: " "${snapshot.data!.type}"),
                          Text("Brug: " "${snapshot.data!.use}"),
                          Text("Første registrerings dato: ""${snapshot.data!.first_registration}"),
                          Text("Vin nummer: " "${snapshot.data!.vin}"),
                          Text("Mærke: " "${snapshot.data!.make}"),
                          Text("Model: " "${snapshot.data!.model}"),
                          Text("Variant: " "${snapshot.data!.variant}"),
                          Text("Model type: ""${snapshot.data!.model_type}"),
                          Text("Farve: " "${snapshot.data!.color}"),
                          Text("Bil type: " "${snapshot.data!.chasis_type}"),
                          Text("Brændstof: " "${snapshot.data!.fuel_type}"),
                          Text("Sidste syn: " "${snapshot.data!.date}"),
                          Text(nummerpladeController.text)
                        ],
                      );
                    } else if (snapshot.hasError) {
                      return Text('${snapshot.error}');
                    }
                    // By default, show a loading spinner.
                    return const CircularProgressIndicator();
                  },
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

我尝试使用“Text(nummerpladeController.text)”并将文本字段中的值插入 api url。基本上是输入一个号码牌,将它的值插入到 api url 中以显示来自 api 的信息。

Future<Album> fetchAlbum() async {
  final response = await http
      .get(Uri.parse('https://v1.motorapi.dk/vehicles/(Value from textfield)'),
       headers: {"X-AUTH-TOKEN": "rfrzsucnc7eo3m5hcmq6ljdzda1lz793",
        "Content-Type": "application/json",
        "Accept": "application/json",
      });

  if (response.statusCode == 200) {
    // If the server did return a 200 OK response,
    // then parse the JSON.
    return Album.fromJson(jsonDecode(response.body));
  } else {
    // If the server did not return a 200 OK response,
    // then throw an exception.
    throw Exception('Failed to load album');
  }
}

我不知道这是否会有所不同,但我的 Future 名列前茅,之后的课程。

【问题讨论】:

  • fetchAlbum 在 initState 中被调用,这意味着在你输入任何内容之前fetchAlbum 将被调用。
  • @nitishk72 我该如何解决这个问题,以便我可以从文本字段中获取值并将其插入 api url?
  • 什么时候调用api?是否有任何按钮可以调用 api?
  • @nitishk72 不,我没有添加按钮,我是 Flutter 新手
  • @nitishk72 我给你发了一封电子邮件

标签: flutter android-studio


【解决方案1】:

您在 TextFormField 中输入了一些值后调用了该函数,然后您必须将相同的值传递给您的函数,然后它将返回您的值

class _MyAppState extends State<MyApp> {
  late Future<Album> futureAlbum;
  late TextEditingController nummerpladeController = new TextEditingController();


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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Fetch Data Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Fetch Data Example'),
        ),
        body:
        Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            children: [
              TextField(
                controller: nummerpladeController,
                onChanged: (str) {
                  fetchAlbum(str);
                },
              ),
              Center(
                child: FutureBuilder<Album>(
                  future: futureAlbum,
                  builder: (context, snapshot) {
                    if (snapshot.hasData) {
                      return new Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        crossAxisAlignment: CrossAxisAlignment.center,
                        children: [
                          Text("Registreringsnummer: ""${snapshot.data!.registration_number}"),
                          Text("Status: " "${snapshot.data!.status}"),
                          Text("Type: " "${snapshot.data!.type}"),
                          Text("Brug: " "${snapshot.data!.use}"),
                          Text("Første registrerings dato: ""${snapshot.data!.first_registration}"),
                          Text("Vin nummer: " "${snapshot.data!.vin}"),
                          Text("Mærke: " "${snapshot.data!.make}"),
                          Text("Model: " "${snapshot.data!.model}"),
                          Text("Variant: " "${snapshot.data!.variant}"),
                          Text("Model type: ""${snapshot.data!.model_type}"),
                          Text("Farve: " "${snapshot.data!.color}"),
                          Text("Bil type: " "${snapshot.data!.chasis_type}"),
                          Text("Brændstof: " "${snapshot.data!.fuel_type}"),
                          Text("Sidste syn: " "${snapshot.data!.date}"),
                          Text(nummerpladeController.text)
                        ],
                      );
                    } else if (snapshot.hasError) {
                      return Text('${snapshot.error}');
                    }
                    // By default, show a loading spinner.
                    return const CircularProgressIndicator();
                  },
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

Future<Album> fetchAlbum(String str) async {
  final response = await http
      .get(Uri.parse('https://v1.motorapi.dk/vehicles/$str'),
       headers: {"X-AUTH-TOKEN": "rfrzsucnc7eo3m5hcmq6ljdzda1lz793",
        "Content-Type": "application/json",
        "Accept": "application/json",
      });

  if (response.statusCode == 200) {
    // If the server did return a 200 OK response,
    // then parse the JSON.
    return Album.fromJson(jsonDecode(response.body));
  } else {
    // If the server did not return a 200 OK response,
    // then throw an exception.
    throw Exception('Failed to load album');
  }
}

【讨论】:

  • 我尝试粘贴您提供的代码,但是当我运行应用程序时,它出现红屏,上面显示:LateIntializerError: Field 'futureAlbum' has not been initialized.
  • 我已经解决了这个问题,但是现在当我在文本字段中输入内容时,它一直显示加载微调器并且不从 API 返回数据
  • 这将在您在 Textfield 中输入正确的详细信息后显示数据。
  • @Diwyanish 我确定我输入了正确的详细信息,但我注意到日志中有一些内容。在 API url 中,如果我只是像这样在 url 中键入车牌号:https://v1.motorapi.dk/vehicles/cz33849 它会起作用,但是当我在文本字段中键入 cz33849 时,错误日志会显示:E/flutter (6773): [ERROR:flutter/lib/ui /ui_dart_state.cc(209)] 未处理的异常:异常:无法加载专辑 E/flutter (6773):#0 fetchAlbum (package:untitled2/main.dart:171:5) E/flutter (6773):.
  • 好的,让我检查一下
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