TextChanged Event in UI for WPF ComboBox

lkeel

115 posts

Member since:
Jul 2012

Posted 15 Jun 2010 Link to this post

What is the WPF equivalent of the TextChanged event? I have a RadComboBox that allows editing and when the text changes I need to raise perform some work.

Thanks in advance,

Lee

Boyan

Admin

758 posts

Posted 17 Jun 2010 Link to this post

Hello lkeel,

In WPF you can use TextBoxBase.TextChanged event. So just set in xaml:

TextBoxBase.TextChanged="combo1_TextChanged"

Let me know if you need more help.

All the best,
Boyan
the Telerik team

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lkeel

115 posts

Member since:
Jul 2012

Posted 17 Jun 2010 Link to this post

Apparently I am confused... I don't see TextBoxBase as a property or method from the RadComboBox. If my combobox is named "combo" then what code would I use to get to the TextBoxBase? Is it a straight QI?

Boyan

Admin

758 posts

Posted 22 Jun 2010 Link to this post

Hi lkeel,

TextBoxBase.TextChanged is an attached property. Your XAML will look like this:

<telerikInput:RadComboBox Height="20" Width="200" x:Name="combo" TextBoxBase.TextChanged="combo_TextChanged" >

This way you will trigger this event with every symbol you type or every Text change. Then just put the code you want to execute in combo_TextChanged in the code behind.

Let me know if you have further questions.

Best wishes,
Boyan
the Telerik team

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Ivano

39 posts

Member since:
Feb 2009

Posted 27 Jan 2011 Link to this post

Hi

how can I do everything in code behind?

Thanks

Ken

3 posts

Member since:
Dec 2011

Posted 30 May 2012 Link to this post

Something like this?

this.comboBox.AddHandler(TextBoxBase.TextChangedEvent, new RoutedEventHandler((o,e) =>

{

var currentText = this.comboBox.Text;

// do something now...

}));

Boyan

Admin

758 posts

Posted 04 Jun 2012 Link to this post

Hello,

Yes this is will do, you can attach to the event in code this way. If you are having problems making it work, we will be glad to help.

Kind regards,
Boyan
the Telerik team

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Anna Katrina

9 posts

Member since:
Feb 2013

Posted 25 Aug 2015 Link to this post

Hi,

I have trying to apply the same event on my radcombobox as well but seems like textchangedevent is no longer available

<telerik:RadComboBox x:Name="rcboDocSize" DisplayMemberPath="FontSizeName" IsEditable="True" MaxDropDownHeight="190" Width="70" SelectionChanged="rcboDocSize_SelectionChanged" StaysOpenOnEdit="True" />

when i typedin it says, The property 'TextChanged' was not found in type 'RadComboBox'. Any help about this?

Nasko

Admin

727 posts

Posted 26 Aug 2015 Link to this post

Hi Anna,

RadComboBox does not support TextChanged event by design. However, you have two appraoches that you could use in order to achieve the desired.

The first one is the proposed by Boyan below to use the TextBoxBase.TextChanged attached property:

<telerik:RadComboBox x:Name="rcboDocSize" DisplayMemberPath="FontSizeName" IsEditable="True" MaxDropDownHeight="190" Width="70" SelectionChanged="rcboDocSize_SelectionChanged" StaysOpenOnEdit="True"

TextBoxBase.TextChanged="radComboBox_TextChanged"/>

and in code - behind:

private void radComboBox_TextChanged(object sender, TextChangedEventArgs e)

{

//implement custom logic here

}

The second approach that you could use to handle to the TextChanged event is to get the TextBox placed inside RadComboBox using the ChildrenOfType method (inside the Loaded event) and handle its TextChanged event:

private void radComboBox_Loaded(object sender, RoutedEventArgs e)

{

var combo = sender as RadComboBox;

var textBox = combo.ChildrenOfType<TextBox>().FirstOrDefault();

if(textBox != null)

{

textBox.TextChanged += textBox_TextChanged;

}

void textBox_TextChanged(object sender, TextChangedEventArgs e)

{

//implement custom logic

}

Hopes this helps.

Regards,
Nasko
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Anna Katrina

9 posts

Member since:
Feb 2013

Posted 26 Aug 2015 in reply to Nasko Link to this post

Thanks for the reply Nasko..

I have added the TextBoxBase.TextChanged="radComboBox_TextChanged" however it gives me this error on the xaml file:

'The attachable property 'TextChanged' was not found in type 'TextBoxBase'

Am i missing header or something in the xaml?

I have also tried working with the loaded event but it throws me a framework element error..

Thanks in advance. Your help is very much appreciated.

Nasko

Admin

727 posts

Posted 28 Aug 2015 Link to this post

Hello Anna,

We tried to reproduce the observed by you error but it seems everything works as expected on our side.

I am attaching you a sample project that demonstrates the approach with the TextBoxBase.TextChanged attached event - please, check it.

Hopes this helps.

Regards,
Nasko
Telerik

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RadComboBoxWPF.rar

Flemming

16 posts

Member since:
Aug 2015

Posted 04 May 2018 Link to this post

How can I attach this event to a reactive linq event like this:

var input = (from evt in Observable.FromEventPattern(myradcombobox, "TextChanged")

var input = (from evt in Observable.FromEventPattern(myradcombobox, "TextBoxBase.TextChanged")

Both throws error that it's not found.

Martin Ivanov

Admin

2420 posts

Posted 09 May 2018 Link to this post

Hello Flemming,

I checked this on my side and I hit the following error - "Could not find event 'TextChanged' on object of type 'Telerik.Windows.Controls.RadComboBox'.". I am not familiar with the Reactive Linq framework but I will guess that the FromEventPattern method is searching for direct events only. And since the TextChanged is not an event of RadComboBox you can't get the proper event pattern.

To achieve your requirement you can subscribe the Loaded event of the combobox where you can get the TextBox element and use the reactive linq on it.

private void Combobox_Loaded(object sender, RoutedEventArgs e)

{

var textBox = this.combobox.FindChildByType<TextBox>();

var input = from evt in Observable.FromEventPattern(textBox, "TextChanged") select evt;

}

Regards,
Martin Ivanov
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