Flutter學習-10 form組件

Textfiled可以提供輸入的功能，也可以檢查格式，像是利用keyboardType這個屬性檢查是否符合以下類型 .number .text .phone .datetime .emailAdress .url但基本上它所提供的檢查方法，都較為簡單，若有很多 表單要輸入，而輸入時要判斷裡面輸入的內容是否正確，就要用到Form來統一提供檢查輸入內容是否正確的功能。

Form的方法與屬性如下:

const Form({
  Key? key,  //Form的key，這個key在form常會用到。
  required this.child,  //內容
  this.onWillPop,  //傳出去的連結是否要提供navigator回傳至上一頁。
  this.onChanged,  //改變時的回調
  AutovalidateMode? autovalidateMode,  //autovalidateMode: AutovalidateMode.onUserInteraction,

key  的使用可參考:http://acao0429.blogspot.com/2022/08/flutter10-1-key.html

Navigator 的使用可參考:https://yanwei-liu.medium.com/learning-navigation-route-of-flutter-bbc0ee964222

在Form裡面會包著 很多TextFormField()輸入內容。
TextFormField()有以下的屬性，基本上跟TextField是相同的。

可參考:http://acao0429.blogspot.com/search?updated-max=2022-08-07T10:04:00-07:00&max-results=3

TextFormField({
  Key? key,
  this.controller,
  String? initialValue,
  FocusNode? focusNode,
  InputDecoration? decoration = const InputDecoration(),
  TextInputType? keyboardType,
  TextCapitalization textCapitalization = TextCapitalization.none,
  TextInputAction? textInputAction,
  TextStyle? style,
  StrutStyle? strutStyle,
  TextDirection? textDirection,
  TextAlign textAlign = TextAlign.start,
  TextAlignVertical? textAlignVertical,
  bool autofocus = false,
  bool readOnly = false,
  ToolbarOptions? toolbarOptions,
  bool? showCursor,
  String obscuringCharacter = '•',
  bool obscureText = false,
  bool autocorrect = true,
  SmartDashesType? smartDashesType,
  SmartQuotesType? smartQuotesType,
  bool enableSuggestions = true,
  MaxLengthEnforcement? maxLengthEnforcement,
  int? maxLines = 1,
  int? minLines,
  bool expands = false,
  int? maxLength,
  ValueChanged<String>? onChanged,
  GestureTapCallback? onTap,
  VoidCallback? onEditingComplete,
  ValueChanged<String>? onFieldSubmitted,
  FormFieldSetter<String>? onSaved,
  FormFieldValidator<String>? validator,
  List<TextInputFormatter>? inputFormatters,
  bool? enabled,
  double cursorWidth = 2.0,
  double? cursorHeight,
  Radius? cursorRadius,
  Color? cursorColor,
  Brightness? keyboardAppearance,
  EdgeInsets scrollPadding = const EdgeInsets.all(20.0),
  bool? enableInteractiveSelection,
  TextSelectionControls? selectionControls,
  InputCounterWidgetBuilder? buildCounter,
  ScrollPhysics? scrollPhysics,
  Iterable<String>? autofillHints,
  AutovalidateMode? autovalidateMode,
  ScrollController? scrollController,
  String? restorationId,
  bool enableIMEPersonalizedLearning = true,
  MouseCursor? mouseCursor,

這裡只介紹validator的用法。

在validator中可以檢查你輸入的時候，是否符合你要求格式的要求，並將它顯示在框的上面。