CheckBox

in namespace DotVVM.Framework.Controls

Renders the HTML checkbox control.

Usage & Scenarios

This control renders HTML checkbox.

Sample 1: Basic CheckBox

The CheckBox control has the Checked property of boolean which indicates whether the control is checked or not.

Optionally, you can use the Text property to specify the label for the checkbox. Or you can put the label contents inside the dot:CheckBox element.

page.dothtml
ViewModel.cs

<dot:CheckBox Text="CheckBox Label" Checked="{value: Checked}" />

<p>{{value: Checked}}</p>

using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.CheckBox.sample1
{
    public class ViewModel : DotvvmViewModelBase
    {
        
        public bool Checked { get; set; }
        
    }
}

Sample 2: Multiple CheckBoxes

The CheckBox has also a property CheckedItems which can hold any collection. This is an alternative to the Checked property - they cannot be combined. The collection holds values of all checkboxes which are checked. The value of the checkbox which should be inserted in the collection, is defined in the CheckedValue property.

The first two checkboxes will be checked by default because the collection holds initial values "r" and "g". If you uncheck or check a checkbox, the collection will be updated immediately.

You can also modify the collection contents in the viewmodel code which will update the checkbox check states appropriately.

page.dothtml
ViewModel.cs

<dot:CheckBox Text="Red" CheckedItems="{value: Colors}" CheckedValue="r" Changed="{command: UpdateSelectedColors()}" />
<dot:CheckBox Text="Green" CheckedItems="{value: Colors}" CheckedValue="g" Changed="{command: UpdateSelectedColors()}" />
<dot:CheckBox Text="Blue" CheckedItems="{value: Colors}" CheckedValue="b" Changed="{command: UpdateSelectedColors()}" />

<p>{{value: SelectedColors}}</p>

using System.Linq;
using System.Collections.Generic;

namespace DotvvmWeb.Views.Docs.Controls.builtin.CheckBox.sample2
{
    public class ViewModel
    {
        public string SelectedColors { get; set; }

        public List<string> Colors { get; set; } = new List<string>() {"r", "g"};

        public ViewModel()
        {
            UpdateSelectedColors();
        }

        public void UpdateSelectedColors()
        {
            SelectedColors = string.Join(", ", Colors.Select(i => i.ToString()));
        }
    }
}

Sample 3: CheckBox's Changed Event

The CheckBox has the Changed event which is fired whenever the checkbox is checked or unchecked.

page.dothtml
ViewModel.cs

<dot:CheckBox Checked="{value: Value}" Changed="{command: OnChanged()}" />

<p>{{value: NumberOfChanges}}</p>

using System.Collections.Generic;

namespace DotvvmWeb.Views.Docs.Controls.builtin.CheckBox.sample3
{
    public class ViewModel
    {
        public bool Value { get; set; }

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

        public void OnChanged()
        {
            NumberOfChanges++;
        }

    }
}

Real World Sample

The total price is calculated by summing of all CheckedValues and is updated after any change by Changed event.

Because the collection holds floats instead of strings, we have to use the {value: 0.5} binding instead of just "0.5". It would be treated as string otherwise.

page.dothtml
ViewModel.cs

<h3>Additional ingredients for your pizza!</h3>
<p>
    <dot:CheckBox CheckedItems="{value: Extra}" 
                  Changed="{command: UpdatePrice()}" 
                  CheckedValue="{value: 0.5}" Text="Jalapeño" />
    <br />

    <dot:CheckBox CheckedItems="{value: Extra}" 
                  Changed="{command: UpdatePrice()}" 
                  CheckedValue="{value: 0.45}" Text="Egg" />
    <br />

    <dot:CheckBox CheckedItems="{value: Extra}" 
                  Changed="{command: UpdatePrice()}" 
                  CheckedValue="{value: 0.75}" Text="Tuna" />
    <br />

    <dot:CheckBox CheckedItems="{value: Extra}" 
                  Changed="{command: UpdatePrice()}" 
                  CheckedValue="{value: 0.2}" Text="Garlic" />
    <br />

    <dot:CheckBox CheckedItems="{value: Extra}" 
                  Changed="{command: UpdatePrice()}" 
                  CheckedValue="{value: 0.8}" Text="Magic Mushrooms" />
</p>

<p>Total price: ${{value: Price}}</p>

using System.Collections.Generic;
using System.Linq;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.builtin.CheckBox.sample4
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<float> Extra { get; set; } = new List<float>();

        public float Price { get; set; } = 4;

        public void UpdatePrice()
        {
            Price = 4 + Extra.DefaultIfEmpty(0).Sum();
        }

    }
}

Properties

Name	Type	Description	Notes	Default Value
Checked	Boolean	Gets or sets whether the control is checked.	attribute inner element static value bindable default	False
CheckedItems	IEnumerable	Gets or sets a collection of values of all checked checkboxes. Use this property in combination with the CheckedValue property.	attribute inner element static value bindable default	null
CheckedValue	Object	Gets or sets the value that will be used as a result when the control is checked. Use this property in combination with the CheckedItem or CheckedItems property.	attribute inner element static value bindable default	null
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
Enabled	Boolean	Gets or sets a value indicating whether the control is enabled and can be clicked on.	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
Text	String	Gets or sets the label text that is rendered next to the control.	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
	Changed	Command	Gets or sets the command that will be triggered when the control check state is changed.

HTML produced by the control

With no Text or an inner content specified, the control renders just the checkbox.

<input type="checkbox" data-bind="..." />

If there is a Text or an inner content, the label is rendered around the checkbox.

<label>
  <input type="checkbox" data-bind="..." />
  Text or inner content
</label>