DropdownButtonFormField<T> class Null safety

A FormField that contains a DropdownButton.

This is a convenience widget that wraps a DropdownButton 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.

See also:

Inheritance

Constructors

Creates a DropdownButton widget that is a FormField, wrapped in an InputDecorator.

Properties

autovalidateMode AutovalidateMode
Used to enable/disable this form field auto validation and update its error text.
finalinherited
builder FormFieldBuilder<T>
Function that returns the widget representing this form field. It is passed the form field state as input, containing the current value and validation state of this field.
finalinherited
decoration InputDecoration
The decoration to show around the dropdown button form field.
final
enabled bool
Whether the form is able to receive user input.
finalinherited
hashCode int
The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
initialValue → T?
An optional value to initialize the form field to, or null otherwise.
finalinherited
key Key?
Controls how one widget replaces another widget in the tree.
finalinherited
onChanged ValueChanged<T?>?
Called when the user selects an item.
final
onSaved FormFieldSetter<T>?
An optional method to call with the final value when the form is saved via FormState.save.
finalinherited
restorationId String?
Restoration ID to save and restore the state of the form field.
finalinherited
runtimeType Type
A representation of the runtime type of the object.
read-onlyinherited
validator FormFieldValidator<T>?
An optional method that validates an input. Returns an error string to display if the input is invalid, or null otherwise.
finalinherited

Methods

createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() FormFieldState<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.
protected">@protectedinherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent 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}) 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.
nonVirtual">@nonVirtualinherited