How can I set the length of entered text in a combobox?

Question

How can I set a ComboBox's entered text length?

That it would not be longer, than 20, for example.

i think this nails it http://stackoverflow.com/questions/1572887/how-to-set-maxlength-for-combobox-in-wpf — Jonesopolis, Jul 17 '13 at 12:26

Mr. Noob · Answer 1 · 2014-12-05T01:08:01.930

1

I used PreviewKeyDown event, very simple + you can show warning or something.
Register the method below to your ComboBox.PreviewKeyDown += event,
KeyDown event will not fire if user press Space.

private void ComboBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (ComboBox.Text.Length > 19) // allow max 20 chars
    {
        if (e.Key != Key.Back) // allow removing chars
        {
            e.Handled = true; // block any additional key press if there is more than allowed max
            System.Media.SystemSounds.Beep.Play(); // optional: beep to let user know he is out of space :)
        }
    }
}

edited Dec 05 '14 at 01:08

answered Dec 05 '14 at 00:41

Mr. Noob

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This does work, but also prevents such things as doing SHIFT+LEFT to select all the text and other quirks like that. – Jack B Nimble Oct 24 '17 at 18:59

Liero · Answer 2 · 2015-09-21T07:34:41.990

Just to make the story complete:

you have two options:

Combobox obviously contains TextBox in its template. You need to find a way to access the TextBox, probably through Combobox Template and set it's MaxLength
You probably databind Combobox.Text to a viewmodel property. You can do the validation in viewmodel using INotifyDataErrorInfo or even by throwing an exception from setter. User will see error message if he exceeds the max allowed length. I think this is better from UX perspective. Unfortunatelly it's quite a lot of work to make it work if you are not using INotifyDataErrorInfo yet.

score 0 · Answer 3 · edited May 17 '15 at 11:43

0

On ComboBox Class (MSDN):

<ComboBox>
  Items
</ComboBox>

The entered length depends on the items you put into it. Therefore you cannot set that property. Textboxes however do have a max length:

<TextBox MaxLength="20">
  Text
</TextBox>

edited May 17 '15 at 11:43

Peter Mortensen

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answered Jul 17 '13 at 12:32

MrFox

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Incorrect facts mentioned in the answer. Combobox has IsEditable property and when set to true, user can enter text just like in TextBox. Therefore the entered length depends on user input, not just the ComboBox's items. – Liero Sep 21 '15 at 07:38

Sasha · Accepted Answer · 2015-09-21T05:56:35.140

-1

I found an easy solution via XAML. In ComboBox resources we can set the style for a textbox and via setter set maxlenth.

<ComboBox Name="comboBox" Width="100" IsEditable="True">
    <ComboBox.Resources>
        <Style TargetType="{x:Type TextBox}">
            <Setter Property="MaxLength" Value="yourValue"/>
        </Style>
    </ComboBox.Resources>
</ComboBox>

EDIT: This works with Actipro ComboBox. For usual comboBox to make this work, have a look here

edited Sep 21 '15 at 05:56

answered Jul 18 '13 at 09:52

Sasha

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I would like to use this solution but it doesn't seem to work for me. Am I missing something? – Tiele Declercq Sep 16 '15 at 09:38
@TieleDeclercq I cannot say without seeing your code – Sasha Sep 16 '15 at 10:35
I have the exact code as in your example in a new WPF project. Changed 'yourValue' to 10. But it does not limit me to enter over 10 characters as it does with TextBox. Tested in 4, 4.5 and 4.6 – Tiele Declercq Sep 17 '15 at 10:54
@TieleDeclercq Not sure what's wrong. Can you post your xaml somewhere? – Sasha Sep 17 '15 at 12:00
I've asked this in a new question: http://stackoverflow.com/questions/32630487/limit-the-input-length-of-an-editable-combobox – Tiele Declercq Sep 17 '15 at 12:38
@Sasha can you please share an empty project with this working solution? – netaholic Sep 17 '15 at 14:18
1

Sorry guys. This solution works with Actipro Combobox. With usual combobox should be changes in TextBox template – Sasha Sep 21 '15 at 05:54

How can I set the length of entered text in a combobox?

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