How can I set "maxChars" of the TextInput in an editable ComboBox? - actionscript-3

Question

I want to set the maxChars property of the TextInput of an editable ComboBox. I am currently trimming the text to a set number of characters using a change Event:
private function nameOptionSelector_changeHandler(event:ListEvent):void
{
nameOptionSelector.text = nameOptionSelector.text.substr(0, MAX_LENGTH);
}
This feels like overkill. There's got to be a better way to do this....

Answer 1

My alternative is to use the protected textInput directly. This approach allows the "maxChars" property to be set in the GUI builder or code, just as you would for a normal TextField. Note that zero is a valid value for maxChars and indicates unlimited characters. The override of .childrenCreated() is needed to avoid attempting to set maxChars before the TextInput object exists.
package my.controls
{
import mx.controls.ComboBox;
public class EditableComboBox extends ComboBox
{
public function EditableComboBox()
{
super();
}
private var _maxChars:int = 0;
override protected function childrenCreated():void
{
super.childrenCreated();
// Now set the maxChars property on the textInput field.
textInput.maxChars = _maxChars;
}
public function set maxChars(value:int):void
{
_maxChars = value;
if (textInput != null && value >= 0)
textInput.maxChars = value;
}
public function get maxChars():int
{
return textInput.maxChars;
}
}
}

Answer 2

You could extend ComboBox and override the default maxChars value for the internal TextInput. If you need to set it dynamically, you could add a public method to set the property on the extended class.

Answer 3

Using the suggestion of Stiggler, here is the full solution I implemented:
package
{
import mx.controls.ComboBox;
public class ComboBoxWithMaxChars extends ComboBox
{
public function ComboBoxWithMaxChars()
{
super();
}
private var _maxCharsForTextInput:int;
public function set maxCharsForTextInput(value:int):void
{
_maxCharsForTextInput = value;
if (super.textInput != null && _maxCharsForTextInput > 0)
super.textInput.maxChars = _maxCharsForTextInput;
}
public function get maxCharsForTextInput():int
{
return _maxCharsForTextInput;
}
override public function itemToLabel(item:Object):String
{
var label:String = super.itemToLabel(item);
if (_maxCharsForTextInput > 0)
label = label.substr(0, _maxCharsForTextInput);
return label;
}
}
}