DOT

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Version: 1.0 | 1.1 |

ListBox

in namespace DotVVM.Framework.Controls

Renders the HTML list box.

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
DataSource Object Gets or sets the source collection or a GridViewDataSet that contains data in the control.
attribute
inner element
static value
bindable
default
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
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
InnerText String Gets or sets the inner text of the HTML element.
attribute
inner element
static value
bindable
default
SelectedValue Object Gets or sets the value of the selected item.
attribute
inner element
static value
bindable
default
Size Int32 Gets or sets number of rows visible in this ListBox.
attribute
inner element
static value
bindable
default
10
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.

Usage & Scenarios

Renders the HTML listbox.

HTML Rendered by the Control

The control renders the HTML select:

<select data-bind="..." size="4"></select>

Sample 1: Basic ListBox

The ListBox control has property DataSource which expects an IEnumerable. Each object is treated as an item in the listbox.

The SelectedValue property will contain the selected value.

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

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

        public string SelectedFruit { get; set; }
    }
}

Sample 2: ListBox Size

The ListBox control has the Size property which specifies how many lines will be visible without scrolling.

<dot:ListBox DataSource="{value: Fruits}" 
              SelectedValue="{value: SelectedFruit}" 
              Size="5" />

{{value: SelectedFruit}}
namespace DotvvmWeb.Views.Docs.Controls.builtin.ListBox.sample2
{
    public class ViewModel
    {
        public string[] Fruits { get; set; } 
            = { "Apple", "Banana", "Orange", "Mandarin", "Pear", "Avocado" };

        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.

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

{{value: SelectedFruitId}}
namespace DotvvmWeb.Views.Docs.Controls.builtin.ListBox.sample3
{
    public class ViewModel
    {
        public Fruit[] Fruits { get; set; } = 
        {
            new Fruit(0, "Apple"),
            new Fruit(1, "Banana"),
            new Fruit(2, "Orange")
        };

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

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

        public string Name { get; set; }

        public Fruit(int id, string name)
        {
            Id = id;
            Name = name;
        }
    }
}

Sample 4: SelectionChanged Event

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

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

{{value: Message}}
namespace DotvvmWeb.Views.Docs.Controls.builtin.ListBox.sample4
{
    public class ViewModel
    {
        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: ListBox Game

A simple trivia game - match inventors to inventions.

<h3>Match inventors and inventions</h3>

<dot:ListBox DataSource="{value: Inventors}" SelectedValue="{value: SelectedInventor}"
       DisplayMember="Name" ValueMember="Id"/>

<dot:ListBox DataSource="{value: Inventions}" SelectedValue="{value: SelectedInvention}" />

<dot:Button Text="Check Answers" Click="{command: CheckAnswer()}" />

<p>Points: {{value: Points}}</p>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.ListBox.sample5
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<Inventor> Inventors { get; set; } = new List<Inventor>()
        {
            new Inventor(0, "Thomas Edison", "Lightbulb"),
            new Inventor(1, "Alexander Graham Bell", "Telephone"),
            new Inventor(2, "Benjamin Franklin", "Electricity"),
            new Inventor(3, "Tim Berners Lee", "HTTP Protocol"),
            new Inventor(4, "Sir John Harrington", "Toilet"),
            new Inventor(5, "Emile Berliner", "Gramophone Record")
        };

        public int? SelectedInventor { get; set; } = null;

        public List<string> Inventions { get; set; }

        public string SelectedInvention { get; set; }

        public int Points { get; set; } = 0;

        public override Task Init()
        {
            // generate random order when the page is loaded the first time
            if (!Context.IsPostBack)
            {
                Inventions = Inventors
                    .OrderBy(i => Guid.NewGuid())
                    .Select(i => i.Invention)
                    .ToList();
            }

            return base.Init();
        }

        public void CheckAnswer()
        {
            var selectedInventor = Inventors.First(i => i.Id == SelectedInventor);
            if (selectedInventor.Invention == SelectedInvention)
            {
                Inventors.Remove(selectedInventor);
                Inventions.Remove(selectedInventor.Invention);

                SelectedInventor = null;
                SelectedInvention = null;

                Points++;
            }
            else
            {
                Points = Points - 2;
            }
        }
    }

    public class Inventor
    {
        public string Name { get; set; }

        public string Invention { get; set; }

        public int Id { get; set; }

        public Inventor()
        {

        }
        public Inventor(int id, string name, string invention)
        {
            Id = id;
            Name = name;
            Invention = invention;
        }
    }
}

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