How do I get combobox to display the text if the user starts typing characters contained on the combobox collection? C#

Question

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for example
the collection has an item "Student"
if the user start typing "S", the combobox text should look for that character and start displaying/ suggesting the "Student" text. if character dont match it stays blank

What I have tried:

private void cmbType_TextChanged(object sender, EventArgs e)
{
if (cmbType.Text.Contains(cmbType.Text.ToUpper()))
{
var items = this.cmbType.GetItemText(this.cmbType.SelectedItem);
//var type = cmbType.Items.ToString().Where(c =>
cmbType.Text.ToUpper().Contains(cmbType.Text.ToUpper()));
cmbType.Text = items;
}
}

Posted 10-Sep-18 7:31am

Member 13975729

Updated 10-Sep-18 8:19am

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Comments

littleGreenDude 10-Sep-18 13:50pm

What combobox is this? Standard Microsoft, Telerik, other?

Look for AutoComplete or AutoCompleteMode property

Member 13975729 10-Sep-18 13:53pm

Windows.Forms.Combobox
it's a .NET app

2 solutions

Solution 1

try this:
class DummyComboBoxItem
{
public string DisplayName
{
get
{
return "Make a selection ...";
}
}
}
public partial class mainForm : Form
{
private DummyComboBoxItem placeholder = new DummyComboBoxItem();
public mainForm()
{
InitializeComponent();

myComboBox.DisplayMember = "DisplayName";
myComboBox.Items.Add(placeholder);
foreach(object o in Objects)
{
myComboBox.Items.Add(o);
}
myComboBox.SelectedItem = placeholder;
}

private void myComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
if (myComboBox.SelectedItem == null) return;
if (myComboBox.SelectedItem == placeholder) return;
/*
do your stuff
*/
myComboBox.Items.Add(placeholder);
myComboBox.SelectedItem = placeholder;
}

private void myComboBox_DropDown(object sender, EventArgs e)
{
myComboBox.Items.Remove(placeholder);
}

private void myComboBox_Leave(object sender, EventArgs e)
{
//this covers user aborting the selection (by clicking away or choosing the system null drop down option)
//The control may not immedietly change, but if the user clicks anywhere else it will reset
if(myComboBox.SelectedItem != placeholder)
{
if(!myComboBox.Items.Contains(placeholder)) myComboBox.Items.Add(placeholder);
myComboBox.SelectedItem = placeholder;
}
}
}

Posted 10-Sep-18 7:57am

Raghav Khurana

Comments

Member 13975729 10-Sep-18 14:45pm

I did not really understand what this code is doing.

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littleGreenDude · Accepted Answer · 2018-09-10T08:20:00

Solution 2

During form load...

// set up source for combo items
string[] items = { "item1", "Student", "Teacher", "Professor", "Teaching Assistent" };

// configure autocompletion for the combobox
AutoCompleteStringCollection allowedTypes = new AutoCompleteStringCollection();
allowedTypes.AddRange(items);
comboBox1.AutoCompleteCustomSource = allowedTypes;
comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
comboBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;

Posted 10-Sep-18 8:20am

littleGreenDude

Comments

Member 13975729 10-Sep-18 14:44pm

This example won't let me enter more than on character in the combo and wont let display suggestions.
it also throws an exception in case i type a letter and then hit backspace.

littleGreenDude 10-Sep-18 14:54pm

Works for me...

I created a Windows form app and draggeda standard combobox control on to the form. In design, clicked on the form. Selected "Events" in the Properties window. Scrolled down to "Load" in the list and added the "Form1_Load" event. Full form code looks like this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
public partial class Form1 : Form
{
public Form1()
{

InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
// set up source for combo items
string[] items = { "item1", "Student", "Teacher", "Professor", "Teaching Assistent" };

// configure autocompletion for the combobox
AutoCompleteStringCollection allowedTypes = new AutoCompleteStringCollection();
allowedTypes.AddRange(items);
comboBox1.AutoCompleteCustomSource = allowedTypes;
comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
comboBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
}
}
}