Add items to comboBox in WPF

Question

When I have added a comboBox to the WPF window, how do I add items to the comboBox? Int the XAML code for the design or in NameOfWindow.xaml.cs file?

Answer 1

I think comboBox1.Items.Add("X"); will add string to ComboBox, instead of ComboBoxItem.

The right solution is

ComboBoxItem item = new ComboBoxItem();
item.Content = "A";
comboBox1.Items.Add(item);

Answer 2

Its better to build ObservableCollection and take advantage of it

public ObservableCollection<string> list = new ObservableCollection<string>();
list.Add("a");
list.Add("b");
list.Add("c");
this.cbx.ItemsSource = list;

cbx is comobobox name

Also Read : Difference between List, ObservableCollection and INotifyPropertyChanged

Answer 3

There are many ways to perform this task. Here is a simple one:

<Window x:Class="WPF_Demo1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     x:Name="TestWindow"
    Title="MainWindow" Height="500" Width="773">

<DockPanel LastChildFill="False">
    <StackPanel DockPanel.Dock="Top" Background="Red" Margin="2">
        <StackPanel Orientation="Horizontal" x:Name="spTopNav">
            <ComboBox x:Name="cboBox1" MinWidth="120"> <!-- Notice we have used x:Name to identify the object that we want to operate upon.-->
            <!--
                <ComboBoxItem Content="X"/>
                <ComboBoxItem Content="Y"/>
                <ComboBoxItem Content="Z"/>
            -->
            </ComboBox>
        </StackPanel>
    </StackPanel>
    <StackPanel DockPanel.Dock="Bottom" Background="Orange" Margin="2">
        <StackPanel Orientation="Horizontal" x:Name="spBottomNav">
        </StackPanel>
        <TextBlock Height="30" Foreground="White">Left Docked StackPanel 2</TextBlock>
    </StackPanel>
    <StackPanel MinWidth="200" DockPanel.Dock="Left" Background="Teal" Margin="2" x:Name="StackPanelLeft">
        <TextBlock  Foreground="White">Bottom Docked StackPanel Left</TextBlock>

    </StackPanel>
    <StackPanel DockPanel.Dock="Right" Background="Yellow" MinWidth="150" Margin="2" x:Name="StackPanelRight"></StackPanel>
    <Button Content="Button" Height="410" VerticalAlignment="Top" Width="75" x:Name="myButton" Click="myButton_Click"/>


</DockPanel>

</Window>      

Next, we have the C# code:

    private void myButton_Click(object sender, RoutedEventArgs e)
    {
        ComboBoxItem cboBoxItem = new ComboBoxItem(); // Create example instance of our desired type.
        Type type1 = cboBoxItem.GetType();
        object cboBoxItemInstance = Activator.CreateInstance(type1); // Construct an instance of that type.
        for (int i = 0; i < 12; i++)
        {
            string newName = "stringExample" + i.ToString();
           // Generate the objects from our list of strings.
            ComboBoxItem item = this.CreateComboBoxItem((ComboBoxItem)cboBoxItemInstance, "nameExample_" + newName, newName);
            cboBox1.Items.Add(item); // Add each newly constructed item to our NAMED combobox.
        }
    }
    private ComboBoxItem CreateComboBoxItem(ComboBoxItem myCbo, string content, string name)
    {
        Type type1 = myCbo.GetType();
        ComboBoxItem instance = (ComboBoxItem)Activator.CreateInstance(type1);
        // Here, we're using reflection to get and set the properties of the type.
        PropertyInfo Content = instance.GetType().GetProperty("Content", BindingFlags.Public | BindingFlags.Instance);
        PropertyInfo Name = instance.GetType().GetProperty("Name", BindingFlags.Public | BindingFlags.Instance);
        this.SetProperty<ComboBoxItem, String>(Content, instance, content);
        this.SetProperty<ComboBoxItem, String>(Name, instance, name);

        return instance;
        //PropertyInfo prop = type.GetProperties(rb1);
    }

Note: This is using reflection. If you'd like to learn more about the basics of reflection and why you might want to use it, this is a great introductory article:

• An Introduction to Reflection in .NET

If you'd like to learn more about how you might use reflection with WPF specifically, here are some resources:

• Reflection for WPF Rockstars
• Use the Power of Reflection to Create and Manipulate Managed Objects

And if you want to massively speed up the performance of reflection, it's best to use IL to do that, like this:

• Fast version of the ActivatorCreateInstance method using IL

• Fast Dynamic Property and Field Accessors

Answer 4

Use this

string[] str = new string[] {"Foo", "Bar"};

myComboBox.ItemsSource = str;
myComboBox.SelectedIndex = 0;

OR

foreach (string s in str)
    myComboBox.Items.Add(s);

myComboBox.SelectedIndex = 0;      

Answer 5

With OleDBConnection -> connect to Oracle

OleDbConnection con = new OleDbConnection();
            con.ConnectionString = "Provider=MSDAORA;Data Source=oracle;Persist Security Info=True;User ID=system;Password=**********;Unicode=True";

            OleDbCommand comd1 = new OleDbCommand("select name from table", con);
            OleDbDataReader DR = comd1.ExecuteReader();
            while (DR.Read())
            {
                comboBox_delete.Items.Add(DR[0]);
            }
            con.Close();

That's all :)

Answer 6

Scenario 1 - you don't have a data-source for the items of the ComboBox
You can just populate the ComboBox with static values as follows -
From XAML:

<ComboBox Height="23" Name="comboBox1" Width="120">
        <ComboBoxItem Content="X"/>
        <ComboBoxItem Content="Y"/>
        <ComboBoxItem Content="Z"/>
</ComboBox>  

Or, from CodeBehind:

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    comboBox1.Items.Add("X");
    comboBox1.Items.Add("Y");
    comboBox1.Items.Add("Z");
}  

Scenario 2.a - you have a data-source, and the items never get changed
You can use the data-source to populate the ComboBox. Any IEnumerable type can be used as the data-source. You need to assign it to the ItemsSource property of the ComboBox and that'll do just fine (it's up to you how you populate the IEnumerable).

Scenario 2.b - you have a data-source, and the items might get changed
You should use an ObservableCollection<T> as the data-source and assign it to the ItemsSource property of the ComboBox (it's up to you how you populate the ObservableCollection<T>). Using an ObservableCollection<T> ensures that whenever an item is added to or removed from the data-source, the change will reflect immediately on the UI.