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WPF Autocomplete Textbox Control

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4.52 (35 votes)
31 May 2008CPOL
An article showing how to build a WPF autocomplete textbox control with delay input
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This article demonstrates some basic steps on how to build an auto complete textbox custom control with WPF. I have looked at many auto completion textbox solutions, most of them suffered performance issues when filled with large amount of entries. This implementation attempts to mask that problem by not building the suggested list until the user is done typing.


I needed an autocompletion textbox for my application that can search based not just on name but also on keywords. I found the solution posted by pfemiani. I like his idea of searching by keywords but the solution does not work for my WPF application without extensive modification. Then I came across a WPF solution from using a textbox and combobox controls, so I decided to build my code upon that.

Ernest's suggestion is pretty simple, there are two children in the control, Textbox and Combobox. On the TextBox's TextChanged event, we would populate the list for the combobox using words matching the text in the textbox. On the ComboBox's SelectionChanged event, we set the text in the textbox using the content of the selected item of the Combobox. This works very well except that Ernest is only doing name matching and his blog doesn't provide the complete source code.

Another challenge that I'm facing is performance issue. My autocompletion textbox is backed by several thousand entries from a database, on some keyword I could have over 300 hits. Populating the combobox on every user keystroke feels sluggish. My solution is to start a timer on TextChanged event and populate the combobox list only when the timer expires. I tried this on my large database and it works beautifully. I can type a long name and not feel like I'm on a 286.

Using the Code

To use this custom control in your application, you simply add the following files...

  1. AutoCompleteEntry.cs
  2. AutoCompleteTextBox.xaml
  3. AutoCompleteTextBox.xaml.cs

... to your project. Next, in the XAML file that you would like to use the auto complete textbox custom control, add this line to the header block.


Then in the XAML code, where you want to place the auto complete textbox, add:

<local:AutoCompleteTextBox Height="23" Width="240" x:Name="textBox1" 

    DelayTime="500" Threshold="2"/>

In my example code, the name of the textbox is textBox1. You can get or set the text in the textbox by referring to textBox1.Text. The DelayTime property is the amount of time (in ms) that you want to delay after the user starts typing before populating the list. Leaving the DelayTime unset will default to 0, which is populating immediately after each user keystroke. The Threshold property controls the number of characters threshold, at or over that at we will start suggesting.

In the code behind of my example, I manually populate the search entries with a variety of cars and models.

textBox1.AddItem(new AutoCompleteEntry
    ("Toyota Camry", "Toyota Camry", "camry", "car", "sedan"));
textBox1.AddItem(new AutoCompleteEntry
    ("Toyota Corolla", "Toyota Corolla", "corolla", "car", "compact"));
textBox1.AddItem(new AutoCompleteEntry
    ("Toyota Tundra", "Toyota Tundra", "tundra", "truck"));
// null matching string will default with just the name
textBox1.AddItem(new AutoCompleteEntry("Chevy Impala", null));
textBox1.AddItem(new AutoCompleteEntry
    ("Chevy Tahoe", "Chevy Tahoe", "tahoe", "truck", "SUV"));
textBox1.AddItem(new AutoCompleteEntry
    ("Chevrolet Malibu", "Chevrolet Malibu", "malibu", "car", "sedan"));

If for example, the user types in "car", all the entries with the "car" keyword will be suggested.

I hope you find this solution helpful. If you find any errors or have questions, feel free to contact me.


  • 30th May, 2008: First release


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

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Comments and Discussions

Question[My vote of 1] Hey - what's this keyboard for? Pin
tonyt21-Feb-10 16:24
Membertonyt21-Feb-10 16:24 
GeneralIssue with WPF AutoComplete TextBox with Chinese and Japanese inputs Pin
sandyyyyyyyyyy18-Nov-09 23:35
Membersandyyyyyyyyyy18-Nov-09 23:35 
GeneralRe: Issue with WPF AutoComplete TextBox with Chinese and Japanese inputs Pin
Max.Liu.Bela9-Oct-14 16:17
MemberMax.Liu.Bela9-Oct-14 16:17 
GeneralMy vote of 2 Pin
realvasche23-Oct-09 7:36
Memberrealvasche23-Oct-09 7:36 
Questionchinese IME issue Pin
nnnnimisha5-Aug-09 20:17
Membernnnnimisha5-Aug-09 20:17 
QuestionHow can I change the Background Color of the AutoComplete TextBox? Pin
Kunal Chowdhury «IN»23-Jun-09 20:59
professionalKunal Chowdhury «IN»23-Jun-09 20:59 
AnswerRe: How can I change the Background Color of the AutoComplete TextBox? Pin
Trond Andersen22-Oct-09 4:08
MemberTrond Andersen22-Oct-09 4:08 
GeneralNice One Pin
kapil bhavsar7-May-09 23:49
Memberkapil bhavsar7-May-09 23:49 
How bout porting it to Silverlight ..
GeneralMy vote of 2 Pin
RandomEngy14-Apr-09 7:44
MemberRandomEngy14-Apr-09 7:44 
QuestionWait hold on... is your ComboBox hiding behind the text field? Pin
RandomEngy14-Apr-09 7:41
MemberRandomEngy14-Apr-09 7:41 
GeneralThanks!! Pin
DZaK8319-Mar-09 13:11
MemberDZaK8319-Mar-09 13:11 
GeneralAnother alternative Pin
toidy30-Sep-08 7:15
Membertoidy30-Sep-08 7:15 
Generalkeyboard oriented selection Pin
john c gibbons22-Sep-08 5:24
Memberjohn c gibbons22-Sep-08 5:24 
QuestionNo keyboard navigation? Pin
armentage17-Jul-08 4:59
Memberarmentage17-Jul-08 4:59 
GeneralComboBox Selection Pin
Andrewiski2-Jun-08 15:54
MemberAndrewiski2-Jun-08 15:54 
GeneralRe: ComboBox Selection Pin
thomastn2-Jun-08 18:18
Memberthomastn2-Jun-08 18:18 
GeneralRe: ComboBox Selection Pin
Andrewiski5-Jun-08 10:24
MemberAndrewiski5-Jun-08 10:24 
QuestionChanging data set? Pin
Jim Weiler31-May-08 10:32
MemberJim Weiler31-May-08 10:32 
AnswerRe: Changing data set? [modified] Pin
thomastn2-Jun-08 17:53
Memberthomastn2-Jun-08 17:53 
GeneralRe: Changing data set? Pin
boriska00215-Sep-09 1:39
Memberboriska00215-Sep-09 1:39 

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Posted 31 May 2008


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