CustomDropdown<T> class

A highly customizable, production-ready generic dropdown widget wrapping Flutter's DropdownMenu.

Features

Full Layout Customization: Use itemBuilder to create any item UI
Type-Safe Generic Support: Works with any model class via generic type parameter
Icon Support: Add prefixIcon, suffixIcon, leadingIcon, or trailingIcon
Enable/Disable: Control interaction with enabled property
Complete Styling: MenuStyle, border radius, colors, elevation
Validation: Display validation messages with validationMessage
Search & Filter: Built-in search and filter capabilities

Basic Usage

CustomDropdown<String>(
  items: ['Apple', 'Banana', 'Orange'],
  itemBuilder: (context, item) => Text(item),
  onSelected: (value) => print('Selected: $value'),
  label: Text('Choose Fruit'),
)

Model Class with Icons

class Country {
  final String name;
  final String flag;
  Country(this.name, this.flag);
}

CustomDropdown<Country>(
  items: [
    Country('USA', '🇺🇸'),
    Country('India', '🇮🇳'),
    Country('Japan', '🇯🇵'),
  ],
  itemBuilder: (context, country) => Row(
    children: [
      Text(country.flag, style: TextStyle(fontSize: 20)),
      SizedBox(width: 10),
      Text(country.name),
    ],
  ),
  prefixIcon: Icon(Icons.flag),
  onSelected: (value) => setState(() => selected = value),
)

With Validation

CustomDropdown<String>(
  items: ['Option 1', 'Option 2'],
  itemBuilder: (context, item) => Text(item),
  onSelected: (value) => setState(() => selected = value),
  validationMessage: selected == null ? 'Please select an option' : null,
)

Custom Styling

CustomDropdown<String>(
  items: ['Light', 'Dark', 'Auto'],
  itemBuilder: (context, item) => Text(item),
  borderRadius: 12,
  menuBackgroundColor: Colors.blue.shade50,
  menuElevation: 8,
  onSelected: (value) => print(value),
)

Advanced Customization

For complete control, use menuStyle for the dropdown panel and dropdownMenuEntries with custom ButtonStyle for individual items.

Reference: https://api.flutter.dev/flutter/material/DropdownMenu-class.html

Inheritance

Constructors

CustomDropdown({Key? key, required Widget itemBuilder(BuildContext, T item), List<T>? items, List<DropdownMenuEntry<T>>? dropdownMenuEntries, T? initialSelection, ValueChanged<T?>? onSelected, bool enabled = true, bool enableFilter = false, bool enableSearch = true, TextEditingController? controller, TextStyle? textStyle, Object? inputDecorationTheme, MenuStyle? menuStyle, Widget? leadingIcon, Widget? trailingIcon, bool showTrailingIcon = true, FocusNode? trailingIconFocusNode, Widget? selectedTrailingIcon, Widget? label, String? hintText, String? helperText, String? errorText, TextInputType? keyboardType, TextAlign textAlign = TextAlign.start, EdgeInsetsGeometry? expandedInsets, FilterCallback<T>? filterCallback, SearchCallback<T>? searchCallback, Offset? alignmentOffset, List<TextInputFormatter>? inputFormatters, DropdownMenuCloseBehavior closeBehavior = DropdownMenuCloseBehavior.all, int? maxLines = 1, TextInputAction? textInputAction, double? cursorHeight, String? restorationId, MenuController? menuController, bool? requestFocusOnTap, Widget selectedBuilder(BuildContext, T?)?, String? validationMessage, TextStyle? validationTextStyle, double? width, double? menuHeight, Widget? prefixIcon, Widget? suffixIcon, double? borderRadius, Color? menuBackgroundColor, double? menuElevation}): const

Properties

alignmentOffset → Offset?: final
borderRadius → double?: final
closeBehavior → DropdownMenuCloseBehavior: final
controller → TextEditingController?: final
cursorHeight → double?: final
dropdownMenuEntries → List<DropdownMenuEntry<T>>?: final
enabled → bool: final
enableFilter → bool: final
enableSearch → bool: final
errorText → String?: final
expandedInsets → EdgeInsetsGeometry?: final
filterCallback → FilterCallback<T>?: final
hashCode → int: The hash code for this object.
no setterinherited
helperText → String?: final
hintText → String?: final
initialSelection → T?: final
inputDecorationTheme → Object?: final
inputFormatters → List<TextInputFormatter>?: final
itemBuilder → Widget Function(BuildContext, T item): final
items → List<T>?: final
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
keyboardType → TextInputType?: final
label → Widget?: final
leadingIcon → Widget?: final
maxLines → int?: final
menuBackgroundColor → Color?: final
menuController → MenuController?: final
menuElevation → double?: final
menuHeight → double?: final
menuStyle → MenuStyle?: final
onSelected → ValueChanged<T?>?: final
prefixIcon → Widget?: final
requestFocusOnTap → bool?: final
restorationId → String?: final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
searchCallback → SearchCallback<T>?: final
selectedBuilder → Widget Function(BuildContext, T?)?: final
selectedTrailingIcon → Widget?: final
showTrailingIcon → bool: final
suffixIcon → Widget?: final
textAlign → TextAlign: final
textInputAction → TextInputAction?: final
textStyle → TextStyle?: final
trailingIcon → Widget?: final
trailingIconFocusNode → FocusNode?: final
validationMessage → String?: final
validationTextStyle → TextStyle?: final
width → double?: final

Methods

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<CustomDropdown<T>>: Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode: Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String: A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String: Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a one-line detailed description of the object.
inherited
toStringShort() → String: A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited