packages/flutter/lib/src/material/text_form_field.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';

 import 'input_decorator.dart';
 import 'text_field.dart';
 import 'theme.dart';

 export 'package:flutter/services.dart' show SmartQuotesType, SmartDashesType;

 // Examples can assume:
 // // @dart = 2.9

 /// A [FormField] that contains a [TextField].
 ///
 /// This is a convenience widget that wraps a [TextField] widget in a
 /// [FormField].
 ///
 /// A [Form] ancestor is not required. The [Form] simply makes it easier to
 /// save, reset, or validate multiple fields at once. To use without a [Form],
 /// pass a [GlobalKey] to the constructor and use [GlobalKey.currentState] to
 /// save or reset the form field.
 ///
 /// When a [controller] is specified, its [TextEditingController.text]
 /// defines the [initialValue]. If this [FormField] is part of a scrolling
 /// container that lazily constructs its children, like a [ListView] or a
 /// [CustomScrollView], then a [controller] should be specified.
 /// The controller's lifetime should be managed by a stateful widget ancestor
 /// of the scrolling container.
 ///
 /// If a [controller] is not specified, [initialValue] can be used to give
 /// the automatically generated controller an initial value.
 ///
 /// Remember to call [TextEditingController.dispose] of the [TextEditingController]
 /// when it is no longer needed. This will ensure we discard any resources used
 /// by the object.
 ///
 /// By default, `decoration` will apply the [ThemeData.inputDecorationTheme] for
 /// the current context to the [InputDecoration], see
 /// [InputDecoration.applyDefaults].
 ///
 /// For a documentation about the various parameters, see [TextField].
 ///
 /// {@tool snippet}
 ///
 /// Creates a [TextFormField] with an [InputDecoration] and validator function.
 ///
 /// ![If the user enters valid text, the TextField appears normally without any warnings to the user](https://flutter.github.io/assets-for-api-docs/assets/material/text_form_field.png)
 ///
 /// ![If the user enters invalid text, the error message returned from the validator function is displayed in dark red underneath the input](https://flutter.github.io/assets-for-api-docs/assets/material/text_form_field_error.png)
 ///
 /// ```dart
 /// TextFormField(
 ///   decoration: const InputDecoration(
 ///     icon: Icon(Icons.person),
 ///     hintText: 'What do people call you?',
 ///     labelText: 'Name *',
 ///   ),
 ///   onSaved: (String value) {
 ///     // This optional block of code can be used to run
 ///     // code when the user saves the form.
 ///   },
 ///   validator: (String value) {
 ///     return value.contains('@') ? 'Do not use the @ char.' : null;
 ///   },
 /// )
 /// ```
 /// {@end-tool}
 ///
 /// {@tool dartpad --template=stateful_widget_material_no_null_safety}
 /// This example shows how to move the focus to the next field when the user
 /// presses the SPACE key.
 ///
 /// ```dart imports
 /// import 'package:flutter/services.dart';
 /// ```
 ///
 /// ```dart
 /// Widget build(BuildContext context) {
 ///   return Material(
 ///     child: Center(
 ///       child: Shortcuts(
 ///         shortcuts: <LogicalKeySet, Intent>{
 ///           // Pressing space in the field will now move to the next field.
 ///           LogicalKeySet(LogicalKeyboardKey.space): const NextFocusIntent(),
 ///         },
 ///         child: FocusTraversalGroup(
 ///           child: Form(
 ///             autovalidateMode: AutovalidateMode.always,
 ///             onChanged: () {
 ///               Form.of(primaryFocus.context).save();
 ///             },
 ///             child: Wrap(
 ///               children: List<Widget>.generate(5, (int index) {
 ///                 return Padding(
 ///                   padding: const EdgeInsets.all(8.0),
 ///                   child: ConstrainedBox(
 ///                     constraints: BoxConstraints.tight(const Size(200, 50)),
 ///                     child: TextFormField(
 ///                       onSaved: (String value) {
 ///                         print('Value for field $index saved as "$value"');
 ///                       },
 ///                     ),
 ///                   ),
 ///                 );
 ///               }),
 ///             ),
 ///           ),
 ///         ),
 ///       ),
 ///     ),
 ///   );
 /// }
 /// ```
 /// {@end-tool}
 ///
 /// See also:
 ///
 ///  * <https://material.io/design/components/text-fields.html>
 ///  * [TextField], which is the underlying text field without the [Form]
 ///    integration.
 ///  * [InputDecorator], which shows the labels and other visual elements that
 ///    surround the actual text editing widget.
 ///  * Learn how to use a [TextEditingController] in one of our [cookbook recipes](https://flutter.dev/docs/cookbook/forms/text-field-changes#2-use-a-texteditingcontroller).
 class TextFormField extends FormField<String> {
   /// Creates a [FormField] that contains a [TextField].
   ///
   /// When a [controller] is specified, [initialValue] must be null (the
   /// default). If [controller] is null, then a [TextEditingController]
   /// will be constructed automatically and its `text` will be initialized
   /// to [initialValue] or the empty string.
   ///
   /// For documentation about the various parameters, see the [TextField] class
   /// and [new TextField], the constructor.
   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,
     @Deprecated(
       'Use autoValidateMode parameter which provide more specific '
       'behaviour related to auto validation. '
       'This feature was deprecated after v1.19.0.'
     )
     bool autovalidate = false,
     @Deprecated(
       'Use maxLengthEnforcement parameter which provides more specific '
       'behavior related to the maxLength limit. '
       'This feature was deprecated after v1.25.0-5.0.pre.'
     )
     bool maxLengthEnforced = 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 = true,
     TextSelectionControls? selectionControls,
     InputCounterWidgetBuilder? buildCounter,
     ScrollPhysics? scrollPhysics,
     Iterable<String>? autofillHints,
     AutovalidateMode? autovalidateMode,
   }) : assert(initialValue == null || controller == null),
        assert(textAlign != null),
        assert(autofocus != null),
        assert(readOnly != null),
        assert(obscuringCharacter != null && obscuringCharacter.length == 1),
        assert(obscureText != null),
        assert(autocorrect != null),
        assert(enableSuggestions != null),
        assert(autovalidate != null),
        assert(
          autovalidate == false ||
          autovalidate == true && autovalidateMode == null,
          'autovalidate and autovalidateMode should not be used together.'
        ),
        assert(maxLengthEnforced != null),
        assert(
          maxLengthEnforced || maxLengthEnforcement == null,
          'maxLengthEnforced is deprecated, use only maxLengthEnforcement',
        ),
        assert(scrollPadding != null),
        assert(maxLines == null || maxLines > 0),
        assert(minLines == null || minLines > 0),
        assert(
          (maxLines == null) || (minLines == null) || (maxLines >= minLines),
          "minLines can't be greater than maxLines",
        ),
        assert(expands != null),
        assert(
          !expands || (maxLines == null && minLines == null),
          'minLines and maxLines must be null when expands is true.',
        ),
        assert(!obscureText || maxLines == 1, 'Obscured fields cannot be multiline.'),
        assert(maxLength == null || maxLength > 0),
        assert(enableInteractiveSelection != null),
        super(
        key: key,
        initialValue: controller != null ? controller.text : (initialValue ?? ''),
        onSaved: onSaved,
        validator: validator,
        enabled: enabled ?? decoration?.enabled ?? true,
        autovalidateMode: autovalidate
            ? AutovalidateMode.always
            : (autovalidateMode ?? AutovalidateMode.disabled),
        builder: (FormFieldState<String> field) {
          final _TextFormFieldState state = field as _TextFormFieldState;
          final InputDecoration effectiveDecoration = (decoration ?? const InputDecoration())
              .applyDefaults(Theme.of(field.context).inputDecorationTheme);
          void onChangedHandler(String value) {
            field.didChange(value);
            if (onChanged != null) {
              onChanged(value);
            }
          }
          return TextField(
            controller: state._effectiveController,
            focusNode: focusNode,
            decoration: effectiveDecoration.copyWith(errorText: field.errorText),
            keyboardType: keyboardType,
            textInputAction: textInputAction,
            style: style,
            strutStyle: strutStyle,
            textAlign: textAlign,
            textAlignVertical: textAlignVertical,
            textDirection: textDirection,
            textCapitalization: textCapitalization,
            autofocus: autofocus,
            toolbarOptions: toolbarOptions,
            readOnly: readOnly,
            showCursor: showCursor,
            obscuringCharacter: obscuringCharacter,
            obscureText: obscureText,
            autocorrect: autocorrect,
            smartDashesType: smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
            smartQuotesType: smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled),
            enableSuggestions: enableSuggestions,
            maxLengthEnforced: maxLengthEnforced,
            maxLengthEnforcement: maxLengthEnforcement,
            maxLines: maxLines,
            minLines: minLines,
            expands: expands,
            maxLength: maxLength,
            onChanged: onChangedHandler,
            onTap: onTap,
            onEditingComplete: onEditingComplete,
            onSubmitted: onFieldSubmitted,
            inputFormatters: inputFormatters,
            enabled: enabled ?? decoration?.enabled ?? true,
            cursorWidth: cursorWidth,
            cursorHeight: cursorHeight,
            cursorRadius: cursorRadius,
            cursorColor: cursorColor,
            scrollPadding: scrollPadding,
            scrollPhysics: scrollPhysics,
            keyboardAppearance: keyboardAppearance,
            enableInteractiveSelection: enableInteractiveSelection,
            selectionControls: selectionControls,
            buildCounter: buildCounter,
            autofillHints: autofillHints,
          );
        },
      );

   /// Controls the text being edited.
   ///
   /// If null, this widget will create its own [TextEditingController] and
   /// initialize its [TextEditingController.text] with [initialValue].
   final TextEditingController? controller;

   @override
   _TextFormFieldState createState() => _TextFormFieldState();
 }

 class _TextFormFieldState extends FormFieldState<String> {
   TextEditingController? _controller;

   TextEditingController? get _effectiveController => widget.controller ?? _controller;

   @override
   TextFormField get widget => super.widget as TextFormField;

   @override
   void initState() {
     super.initState();
     if (widget.controller == null) {
       _controller = TextEditingController(text: widget.initialValue);
     } else {
       widget.controller!.addListener(_handleControllerChanged);
     }
   }

   @override
   void didUpdateWidget(TextFormField oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.controller != oldWidget.controller) {
       oldWidget.controller?.removeListener(_handleControllerChanged);
       widget.controller?.addListener(_handleControllerChanged);

       if (oldWidget.controller != null && widget.controller == null)
         _controller = TextEditingController.fromValue(oldWidget.controller!.value);
       if (widget.controller != null) {
         setValue(widget.controller!.text);
         if (oldWidget.controller == null)
           _controller = null;
       }
     }
   }

   @override
   void dispose() {
     widget.controller?.removeListener(_handleControllerChanged);
     super.dispose();
   }

   @override
   void didChange(String? value) {
     super.didChange(value);

     if (_effectiveController!.text != value)
       _effectiveController!.text = value ?? '';
   }

   @override
   void reset() {
     super.reset();
     setState(() {
       _effectiveController!.text = widget.initialValue ?? '';
     });
   }

   void _handleControllerChanged() {
     // Suppress changes that originated from within this class.
     //
     // In the case where a controller has been passed in to this widget, we
     // register this change listener. In these cases, we'll also receive change
     // notifications for changes originating from within this class -- for
     // example, the reset() method. In such cases, the FormField value will
     // already have been set.
     if (_effectiveController!.text != value)
       didChange(_effectiveController!.text);
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:flutter/services.dart';
	import 'package:flutter/widgets.dart';

	import 'input_decorator.dart';
	import 'text_field.dart';
	import 'theme.dart';

	export 'package:flutter/services.dart' show SmartQuotesType, SmartDashesType;

	// Examples can assume:
	// // @dart = 2.9

	/// A [FormField] that contains a [TextField].
	///
	/// This is a convenience widget that wraps a [TextField] widget in a
	/// [FormField].
	///
	/// A [Form] ancestor is not required. The [Form] simply makes it easier to
	/// save, reset, or validate multiple fields at once. To use without a [Form],
	/// pass a [GlobalKey] to the constructor and use [GlobalKey.currentState] to
	/// save or reset the form field.
	///
	/// When a [controller] is specified, its [TextEditingController.text]
	/// defines the [initialValue]. If this [FormField] is part of a scrolling
	/// container that lazily constructs its children, like a [ListView] or a
	/// [CustomScrollView], then a [controller] should be specified.
	/// The controller's lifetime should be managed by a stateful widget ancestor
	/// of the scrolling container.
	///
	/// If a [controller] is not specified, [initialValue] can be used to give
	/// the automatically generated controller an initial value.
	///
	/// Remember to call [TextEditingController.dispose] of the [TextEditingController]
	/// when it is no longer needed. This will ensure we discard any resources used
	/// by the object.
	///
	/// By default, `decoration` will apply the [ThemeData.inputDecorationTheme] for
	/// the current context to the [InputDecoration], see
	/// [InputDecoration.applyDefaults].
	///
	/// For a documentation about the various parameters, see [TextField].
	///
	/// {@tool snippet}
	///
	/// Creates a [TextFormField] with an [InputDecoration] and validator function.
	///
	/// ![If the user enters valid text, the TextField appears normally without any warnings to the user](https://flutter.github.io/assets-for-api-docs/assets/material/text_form_field.png)
	///
	/// ![If the user enters invalid text, the error message returned from the validator function is displayed in dark red underneath the input](https://flutter.github.io/assets-for-api-docs/assets/material/text_form_field_error.png)
	///
	/// ```dart
	/// TextFormField(
	/// decoration: const InputDecoration(
	/// icon: Icon(Icons.person),
	/// hintText: 'What do people call you?',
	/// labelText: 'Name *',
	/// ),
	/// onSaved: (String value) {
	/// // This optional block of code can be used to run
	/// // code when the user saves the form.
	/// },
	/// validator: (String value) {
	/// return value.contains('@') ? 'Do not use the @ char.' : null;
	/// },
	/// )
	/// ```
	/// {@end-tool}
	///
	/// {@tool dartpad --template=stateful_widget_material_no_null_safety}
	/// This example shows how to move the focus to the next field when the user
	/// presses the SPACE key.
	///
	/// ```dart imports
	/// import 'package:flutter/services.dart';
	/// ```
	///
	/// ```dart
	/// Widget build(BuildContext context) {
	/// return Material(
	/// child: Center(
	/// child: Shortcuts(
	/// shortcuts: <LogicalKeySet, Intent>{
	/// // Pressing space in the field will now move to the next field.
	/// LogicalKeySet(LogicalKeyboardKey.space): const NextFocusIntent(),
	/// },
	/// child: FocusTraversalGroup(
	/// child: Form(
	/// autovalidateMode: AutovalidateMode.always,
	/// onChanged: () {
	/// Form.of(primaryFocus.context).save();
	/// },
	/// child: Wrap(
	/// children: List<Widget>.generate(5, (int index) {
	/// return Padding(
	/// padding: const EdgeInsets.all(8.0),
	/// child: ConstrainedBox(
	/// constraints: BoxConstraints.tight(const Size(200, 50)),
	/// child: TextFormField(
	/// onSaved: (String value) {
	/// print('Value for field $index saved as "$value"');
	/// },
	/// ),
	/// ),
	/// );
	/// }),
	/// ),
	/// ),
	/// ),
	/// ),
	/// ),
	/// );
	/// }
	/// ```
	/// {@end-tool}
	///
	/// See also:
	///
	/// * <https://material.io/design/components/text-fields.html>
	/// * [TextField], which is the underlying text field without the [Form]
	/// integration.
	/// * [InputDecorator], which shows the labels and other visual elements that
	/// surround the actual text editing widget.
	/// * Learn how to use a [TextEditingController] in one of our [cookbook recipes](https://flutter.dev/docs/cookbook/forms/text-field-changes#2-use-a-texteditingcontroller).
	class TextFormField extends FormField<String> {
	/// Creates a [FormField] that contains a [TextField].
	///
	/// When a [controller] is specified, [initialValue] must be null (the
	/// default). If [controller] is null, then a [TextEditingController]
	/// will be constructed automatically and its `text` will be initialized
	/// to [initialValue] or the empty string.
	///
	/// For documentation about the various parameters, see the [TextField] class
	/// and [new TextField], the constructor.
	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,
	@Deprecated(
	'Use autoValidateMode parameter which provide more specific '
	'behaviour related to auto validation. '
	'This feature was deprecated after v1.19.0.'
	)
	bool autovalidate = false,
	@Deprecated(
	'Use maxLengthEnforcement parameter which provides more specific '
	'behavior related to the maxLength limit. '
	'This feature was deprecated after v1.25.0-5.0.pre.'
	)
	bool maxLengthEnforced = 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 = true,
	TextSelectionControls? selectionControls,
	InputCounterWidgetBuilder? buildCounter,
	ScrollPhysics? scrollPhysics,
	Iterable<String>? autofillHints,
	AutovalidateMode? autovalidateMode,
	}) : assert(initialValue == null \|\| controller == null),
	assert(textAlign != null),
	assert(autofocus != null),
	assert(readOnly != null),
	assert(obscuringCharacter != null && obscuringCharacter.length == 1),
	assert(obscureText != null),
	assert(autocorrect != null),
	assert(enableSuggestions != null),
	assert(autovalidate != null),
	assert(
	autovalidate == false \|\|
	autovalidate == true && autovalidateMode == null,
	'autovalidate and autovalidateMode should not be used together.'
	),
	assert(maxLengthEnforced != null),
	assert(
	maxLengthEnforced \|\| maxLengthEnforcement == null,
	'maxLengthEnforced is deprecated, use only maxLengthEnforcement',
	),
	assert(scrollPadding != null),
	assert(maxLines == null \|\| maxLines > 0),
	assert(minLines == null \|\| minLines > 0),
	assert(
	(maxLines == null) \|\| (minLines == null) \|\| (maxLines >= minLines),
	"minLines can't be greater than maxLines",
	),
	assert(expands != null),
	assert(
	!expands \|\| (maxLines == null && minLines == null),
	'minLines and maxLines must be null when expands is true.',
	),
	assert(!obscureText \|\| maxLines == 1, 'Obscured fields cannot be multiline.'),
	assert(maxLength == null \|\| maxLength > 0),
	assert(enableInteractiveSelection != null),
	super(
	key: key,
	initialValue: controller != null ? controller.text : (initialValue ?? ''),
	onSaved: onSaved,
	validator: validator,
	enabled: enabled ?? decoration?.enabled ?? true,
	autovalidateMode: autovalidate
	? AutovalidateMode.always
	: (autovalidateMode ?? AutovalidateMode.disabled),
	builder: (FormFieldState<String> field) {
	final _TextFormFieldState state = field as _TextFormFieldState;
	final InputDecoration effectiveDecoration = (decoration ?? const InputDecoration())
	.applyDefaults(Theme.of(field.context).inputDecorationTheme);
	void onChangedHandler(String value) {
	field.didChange(value);
	if (onChanged != null) {
	onChanged(value);
	}
	}
	return TextField(
	controller: state._effectiveController,
	focusNode: focusNode,
	decoration: effectiveDecoration.copyWith(errorText: field.errorText),
	keyboardType: keyboardType,
	textInputAction: textInputAction,
	style: style,
	strutStyle: strutStyle,
	textAlign: textAlign,
	textAlignVertical: textAlignVertical,
	textDirection: textDirection,
	textCapitalization: textCapitalization,
	autofocus: autofocus,
	toolbarOptions: toolbarOptions,
	readOnly: readOnly,
	showCursor: showCursor,
	obscuringCharacter: obscuringCharacter,
	obscureText: obscureText,
	autocorrect: autocorrect,
	smartDashesType: smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
	smartQuotesType: smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled),
	enableSuggestions: enableSuggestions,
	maxLengthEnforced: maxLengthEnforced,
	maxLengthEnforcement: maxLengthEnforcement,
	maxLines: maxLines,
	minLines: minLines,
	expands: expands,
	maxLength: maxLength,
	onChanged: onChangedHandler,
	onTap: onTap,
	onEditingComplete: onEditingComplete,
	onSubmitted: onFieldSubmitted,
	inputFormatters: inputFormatters,
	enabled: enabled ?? decoration?.enabled ?? true,
	cursorWidth: cursorWidth,
	cursorHeight: cursorHeight,
	cursorRadius: cursorRadius,
	cursorColor: cursorColor,
	scrollPadding: scrollPadding,
	scrollPhysics: scrollPhysics,
	keyboardAppearance: keyboardAppearance,
	enableInteractiveSelection: enableInteractiveSelection,
	selectionControls: selectionControls,
	buildCounter: buildCounter,
	autofillHints: autofillHints,
	);
	},
	);

	/// Controls the text being edited.
	///
	/// If null, this widget will create its own [TextEditingController] and
	/// initialize its [TextEditingController.text] with [initialValue].
	final TextEditingController? controller;

	@override
	_TextFormFieldState createState() => _TextFormFieldState();
	}

	class _TextFormFieldState extends FormFieldState<String> {
	TextEditingController? _controller;

	TextEditingController? get _effectiveController => widget.controller ?? _controller;

	@override
	TextFormField get widget => super.widget as TextFormField;

	@override
	void initState() {
	super.initState();
	if (widget.controller == null) {
	_controller = TextEditingController(text: widget.initialValue);
	} else {
	widget.controller!.addListener(_handleControllerChanged);
	}
	}

	@override
	void didUpdateWidget(TextFormField oldWidget) {
	super.didUpdateWidget(oldWidget);
	if (widget.controller != oldWidget.controller) {
	oldWidget.controller?.removeListener(_handleControllerChanged);
	widget.controller?.addListener(_handleControllerChanged);

	if (oldWidget.controller != null && widget.controller == null)
	_controller = TextEditingController.fromValue(oldWidget.controller!.value);
	if (widget.controller != null) {
	setValue(widget.controller!.text);
	if (oldWidget.controller == null)
	_controller = null;
	}
	}
	}

	@override
	void dispose() {
	widget.controller?.removeListener(_handleControllerChanged);
	super.dispose();
	}

	@override
	void didChange(String? value) {
	super.didChange(value);

	if (_effectiveController!.text != value)
	_effectiveController!.text = value ?? '';
	}

	@override
	void reset() {
	super.reset();
	setState(() {
	_effectiveController!.text = widget.initialValue ?? '';
	});
	}

	void _handleControllerChanged() {
	// Suppress changes that originated from within this class.
	//
	// In the case where a controller has been passed in to this widget, we
	// register this change listener. In these cases, we'll also receive change
	// notifications for changes originating from within this class -- for
	// example, the reset() method. In such cases, the FormField value will
	// already have been set.
	if (_effectiveController!.text != value)
	didChange(_effectiveController!.text);
	}
	}