ComboBox

in namespace DotVVM.Framework.Controls

Renders the HTML drop-down list.

Usage & Scenarios

Renders the HTML drop-down list.

Sample 1: Basic ComboBox Usage

The ComboBox control has property DataSource which expects an IEnumerable. Each object is treated as an item in the drop-down list.

The SelectedValue property will contain the selected value.

page.dothtml
ViewModel.cs

<dot:ComboBox DataSource="{value: Fruits}" 
              SelectedValue="{value: SelectedFruit}"/>

{{value: SelectedFruit}}

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ComboBox.sample1
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string[] Fruits { get; set; } = { "Apple", "Banana", "Orange" };

        public string SelectedFruit { get; set; }
    }
}

Sample 2: Empty Item

There is the EmptyItemText property which adds an empty item which means that nothing is selected.

The SelectedFruit property will be null when nothing is selected.

page.dothtml
ViewModel.cs

<dot:ComboBox DataSource="{value: Fruits}" 
              SelectedValue="{value: SelectedFruit}" 
              EmptyItemText="Select..." />

{{value: SelectedFruit}}

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ComboBox.sample2
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string[] Fruits { get; set; } = { "Apple", "Banana", "Orange" };

        public string SelectedFruit { get; set; }
    }
}

Sample 3: ValueMember and DisplayMember

Typically, the DataSource is not a collection of strings, but a collection of some complex objects.

The ValueMember property defines which property of the object will be passed to the SelectedValue property.

The DisplayMember property defines which property of the object will be displayed in the drop-down list.

page.dothtml
ViewModel.cs

<dot:ComboBox DataSource="{value: Fruits}" 
              SelectedValue="{value: SelectedFruitId}" 
              ValueMember="Id" 
              DisplayMember="Name" />

{{value: SelectedFruitId}}

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ComboBox.sample3
{
    public class ViewModel : DotvvmViewModelBase
    {
        public Fruit[] Fruits { get; set; } = 
        {
            new Fruit { Id = 0, Name = "Apple" },
            new Fruit { Id = 1, Name = "Banana" },
            new Fruit { Id = 2, Name = "Orange" }
        };

        public int SelectedFruitId { get; set; } = 1;

    }

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

        public string Name { get; set; }
        
    }
}

Sample 4: SelectionChanged Event

The ComboBox control also has the SelectionChanged event which is fired whenever the selection changes.

page.dothtml
ViewModel.cs

<dot:ComboBox DataSource="{value: Fruits}" 
              SelectedValue="{value: SelectedFruit}" 
              SelectionChanged="{command: IsItReallyFruit()}"/>

{{value: Message}}

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ComboBox.sample4
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string[] Fruits { get; set; } = { "Apple", "Banana", "IceCream", "Orange" };

        public string SelectedFruit { get; set; }

        public string Message { get; set; }

        public void IsItReallyFruit()
        {
            if (SelectedFruit == "IceCream")
            {
                Message = "Ice cream isn't a fruit!";
            }
            else
            {
                Message = "Yes, it's a fruit!";
            }
        }
    }
}

Sample 5: Cascading ComboBoxes

This is an example of two connected ComboBoxes.

page.dothtml
ViewModel.cs

<dot:ComboBox DataSource="{value: Groups}" 
              SelectedValue="{value: SelectedGroup}" 
              SelectionChanged="{command: GroupSelectionChanged()}" 
              EmptyItemText="Select Group..."/> 
<br />

<dot:ComboBox DataSource="{value: Items}" 
              SelectedValue="{value: SelectedItem}" 
              Visible="{value: SelectedGroup != null}" /> 
<br />

{{value: SelectedItem}}

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ComboBox.sample5
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string[] Groups { get; set; } = { "Vegetables", "Fruits" };
        
        public string SelectedGroup { get; set; }


        public string[] Items { get; set; }
        
        public string SelectedItem { get; set; }
                


        public void GroupSelectionChanged()
        {
            if (SelectedGroup == "Fruits")
            {
                Items = new string[] { "Apple", "Banana", "Orange" };
            }
            else if (SelectedGroup == "Vegetables")
            {
                Items = new string[] { "Broccolini", "Lettuce", "Cabbage" };
            }
            else
            {
                Items = new string[] { };
            }
        }
    }
}

Properties

Name	Type	Description	Notes	Default Value
ClientIDMode	ClientIDMode	Gets or sets the client ID generation algorithm.	attribute inner element static value bindable default	1
DataContext	Object	Gets or sets a data context for the control and its children. All value and command bindings are evaluated in context of this value.	attribute inner element static value bindable default	null
DataSource	Object	Gets or sets the source collection or a GridViewDataSet that contains data in the control.	attribute inner element static value bindable default	null
DisplayMember	String	Gets or sets the name of property in the DataSource collection that will be displayed in the control.	attribute inner element static value bindable default
EmptyItemText	String		attribute inner element static value bindable default
Enabled	Boolean	Gets or sets a value indicating whether the control is enabled and can be modified.	attribute inner element static value bindable default	True
ID	String	Gets or sets the unique control ID.	attribute inner element static value bindable default	null
InnerText	String	Gets or sets the inner text of the HTML element.	attribute inner element static value bindable default	null
SelectedValue	Object	Gets or sets the value of the selected item.	attribute inner element static value bindable default	null
ValueMember	String	Gets or sets the name of property in the DataSource collection that will be passed to the SelectedValue property when the item is selected.	attribute inner element static value bindable default
Visible	Boolean	Gets or sets whether the control is visible.	attribute inner element static value bindable default	True

Events

	Name	Type	Description
	SelectionChanged	Command	Gets or sets the command that will be triggered when the selection is changed.

HTML produced by the control

The control renders the HTML select element.

<select data-bind="..."></select>