# Data binding

Data binding is a mechanism for automatic population of the **RadDomainUpDown** with items, based on the provided data structure. Three properties control the data binding:

* **DataSource** - specifies the data structure to be bound.

* **DisplayMember** - specifies the particular field in the data source which will be used from the items in **RadDomainUpDown** for their Text.

* **ValueMember** - specifies the particular field in the data source which will be stored in the items **Value** property.

**RadDomainUpDown** supports data binding either at design time or at run time:

## Data binding at design time

You can set the **DataSource** property at design time in the *Properties* window of Visual Studio.

1. Select the **DataSource** property and click the drop-down arrow to display all existing data sources on the form.

2. Click the *Add Project Data Source…* link and follow the instructions in the *Data Source Configuration Wizard*  to add a data source to your project. You can use a single database table.

   > caption Figure: 1 Setting the DataSource at Design Time

   ![WinForms RadDomainUpDown DataSource Design Time](https://www.telerik.com/products/winforms/documentation/assets/5929a90d6042eb653b446200a76aa046/domainupdown-populating-with-data-data-binding001.png)

3. Afterwards, you need to specify the **DisplayMember** and **ValueMember** properties.

   > caption Figure: 2 Setting the DisplayMember and ValueMember properties at Design time

   ![WinForms RadDomainUpDown DisplayMember ValueMember Design time](https://www.telerik.com/products/winforms/documentation/assets/0f80102eac139f1d9adb9b365bd02a27/domainupdown-populating-with-data-data-binding002.png)

   > caption Figure: 3 RadDomainUpDown bound at Design time

   ![WinForms RadDomainUpDown Bound at Design time](https://www.telerik.com/products/winforms/documentation/assets/582a8789543266a0c6b007b4ba9f04c6/domainupdown-populating-with-data-data-binding003.gif)

## Data binding at run time

You can bind **RadDomainUpDown** programmatically as well. The following code snippet demonstrates how to bind it to a collection of custom objects:

#### Data binding at run time

```C#

        public RadForm1()
        {
            InitializeComponent();

            List<Item> items = new List<Item>();
            for (int i = 0; i < 10; i++)
            {
                items.Add(new Item(i, "Data" + i));
            }
            this.radDomainUpDown1.DataSource = items;
            this.radDomainUpDown1.DisplayMember = "Description";
            this.radDomainUpDown1.ValueMember = "Id";
        }

        public class Item
        {
            public int Id { get; set; }

            public string Description { get; set; }

            public Item(int id, string description)
            {
                this.Id = id;
                this.Description = description;
            }
        }

```

```VB.NET

    Sub New()
        InitializeComponent()

        Dim items As New List(Of Item)()
        For i As Integer = 0 To 9
            items.Add(New Item(i, "Data" & i))
        Next
        Me.RadDomainUpDown1.DataSource = items
        Me.RadDomainUpDown1.DisplayMember = "Description"
        Me.RadDomainUpDown1.ValueMember = "Id"
    End Sub

    Public Class Item
        Public Property Id() As Integer
            Get
                Return m_Id
            End Get
            Set(value As Integer)
                m_Id = value
            End Set
        End Property
        Private m_Id As Integer
        Public Property Description() As String
            Get
                Return m_Description
            End Get
            Set(value As String)
                m_Description = value
            End Set
        End Property
        Private m_Description As String
        Public Sub New(id As Integer, description As String)
            Me.Id = id
            Me.Description = description
        End Sub
    End Class


```

> caption Figure: 4 RadDomainUpDown bound at Run time

![WinForms RadDomainUpDown Bound at Run Time](https://www.telerik.com/products/winforms/documentation/assets/093de72fefec592edbcb2a586e468ba5/domainupdown-populating-with-data-data-binding004.gif)

## See Also

* [Populating with Data at Design Time](https://www.telerik.com/products/winforms/documentation/controls/editors/domainupdown/populating-with-data/design-time)
* [Adding Items Programmatically](https://www.telerik.com/products/winforms/documentation/controls/editors/domainupdown/populating-with-data/adding-items-programmatically)
* [Design Time](https://www.telerik.com/products/winforms/documentation/controls/editors/domainupdown/design-time)
* [Getting Started](https://www.telerik.com/products/winforms/documentation/controls/editors/domainupdown/getting-started)
* [Structure](https://www.telerik.com/products/winforms/documentation/controls/editors/domainupdown/structure)