android - 如何在TextFormField下方的errorText中添加图标？

Question

如何使用 Flutter 在 TextFormField 下面的 errorText 中添加图标？

标签： androidiphonefluttermobilemobile-development

Answer 1

Prot_CN，我认为您帖子中的屏幕截图使用的是自定义错误消息，其中包含Icon和Text小部件，因为我不确定内置功能是否允许这样做（我可能是错的）。如果您不想设计自定义错误消息，您可以使用 unicode26A0在错误消息中显示警告符号，如下所示，

这是带有unicode的完整代码，

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  final _formKey = GlobalKey<FormState>();
  final textController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            appBar: AppBar(
              title: Text('Test'),
            ),
            body: Form(
                key: _formKey,
                child: Column(children: <Widget>[
                  Container(
                      padding: const EdgeInsets.all(20.0),
                      child: TextFormField(
                        controller: textController,
                        decoration: new InputDecoration(
                            errorStyle: TextStyle(fontSize: 18.0),
                            labelText: 'Hint text',
                            filled: true,
                            fillColor: Colors.white,
                            enabledBorder: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(25.0),
                              borderSide: new BorderSide(
                                color: Colors.grey,
                              ),
                            ),
                            focusedBorder: new OutlineInputBorder(
                                borderRadius: new BorderRadius.circular(25.0),
                                borderSide: new BorderSide(
                                  color: Colors.blue,
                                )),
                            border: OutlineInputBorder(
                                borderRadius: new BorderRadius.circular(25.0),
                                borderSide: BorderSide(
                                    color: Colors.black, width: 1.0))),
                        style: new TextStyle(color: Colors.black),
                        validator: (value) {
                          if (value.isEmpty) {
                            return '\u26A0 Field is empty.';
                          }
                          return null;
                        },
                      )),
                  Center(
                      child: Padding(
                    padding: EdgeInsets.only(top: 20.0),
                    child: RaisedButton(
                      onPressed: () {
                        // Validate returns true if the form is valid, otherwise false.
                        if (_formKey.currentState.validate()) {
                          // If the form is valid, display a snackbar. In the real world,
                          // you'd often call a server or save the information in a database.

                          Scaffold.of(context).showSnackBar(
                              SnackBar(content: Text('Processing Data')));
                        }
                      },
                      child: Text('Submit'),
                    ),
                  ))
                ]))));
  }
}

此外，这是一个与您的屏幕截图类似的自定义错误消息示例，

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  final _formKey = GlobalKey<FormState>();
  final textController = TextEditingController();
  String errorText = '';
  IconData errorIcon;
  double errorContainerHeight = 0.0;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            appBar: AppBar(
              title: Text('Test'),
            ),
            body: Column(children: <Widget>[
                  Container(
                      padding: const EdgeInsets.only(top: 20.0, left: 20.0, right: 20.0),
                      child: TextFormField(
                        controller: textController,
                        decoration: new InputDecoration(
                          suffixIcon: Icon(Icons.arrow_drop_down, size: 35.0,),
                            labelStyle: TextStyle(fontSize: 18.0),
                            labelText: 'Hint text',
                            filled: true,
                            fillColor: Colors.white,
                            enabledBorder: new OutlineInputBorder(
                              borderRadius: new BorderRadius.circular(5.0),
                              borderSide: new BorderSide(
                                color: errorText.isEmpty ? Colors.grey : Colors.red[700],
                              ),
                            ),
                            focusedBorder: new OutlineInputBorder(
                                borderRadius: new BorderRadius.circular(5.0),
                                borderSide: new BorderSide(
                                  color: errorText.isEmpty ? Colors.blue : Colors.red[700],
                                )),
                            border: OutlineInputBorder(
                                borderRadius: new BorderRadius.circular(5.0),
                                borderSide: BorderSide(
                                    color: Colors.black, width: 1.0))),
                        style: new TextStyle(color: Colors.black),
                      )),
                  Container(
                    padding: EdgeInsets.only(left: 20.0, top: 5.0),
                    height: errorContainerHeight,
                      child: Row(
                    children: <Widget>[
                      Icon(errorIcon, size: 20.0, color: Colors.red[700]),
                      Padding(padding: EdgeInsets.only(left: 5.0),child: Text(errorText, style: TextStyle(fontSize: 16.0, color: Colors.red[700])))
                    ],
                  )),
                  Center(
                      child: Padding(
                    padding: EdgeInsets.only(top: 20.0),
                    child: RaisedButton(
                      onPressed: () {
                        // Validate returns true if the form is valid, otherwise false.
                        if (textController.text.isEmpty) {
                            setState(() {
                              errorContainerHeight = 35.0;
                              errorIcon = FontAwesomeIcons.exclamationCircle;
                              errorText = 'Field is empty.';
                            });
                          } else {
                          setState(() {
                            errorContainerHeight = 0.0;
                            errorIcon = null;
                            errorText = '';
                          });
                        }

                      },
                      child: Text('Submit'),
                    ),
                  ))
                ])));
  }
}

希望这可以帮助。