MultiSelect

in namespace DotVVM.BusinessPack.Controls

Renders a MultiSelect control similar to ComboBox control. It allows to select multiple values.

Usage & Scenarios

The Business Pack MultiSelect control is a text field which suggests items to select and supports multiple selected items.

Sample 1: Basic Usage

The DataSource property specifies a collection of strings. When the user starts interacting with the control, a list of items made from this collection will appear.

The SelectedValues property is bound to a collection which contains all items that are selected. The data-binding works in both ways, so you can either read, or modify the collection in the viewmodel and the selected values in the control will get synchronized to reflect the changes.

The Placeholder specifies the text displayed when the Text is empty.

page.dothtml
ViewModel.cs

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                Placeholder="Select multiple countries" />

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample1
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<string> Countries { get; set; } = new List<string> {
            "Czech Republic", "Slovakia", "United States"
        };

        public List<string> SelectedCountries { get; set; } = new List<string>();
    }
}

Sample 2: Working with Objects

When the DataSource collection is bound to a collection of objects, you may use the ItemTextBinding to specify, which property of the object in the collection will be displayed as a text of a particular checkbox control.

The SelectedValues will contain the objects from the DataSource collection which are checked.

In order to allow the control to uniquely identify these objects, you need to use the ItemKeyBinding property to define a property which can work as a key. The key must be unique for all items in the collection, otherwise the control will not work properly.

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                ItemTextBinding="{value: Name}"
                ItemKeyBinding="{value: Id}"
                Placeholder="Select multiple countries" />

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample2
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<Country> Countries { get; set; } = new List<Country> {
            new Country { Id = 1, Name = "Czech Republic" },
            new Country { Id = 2, Name = "Slovakia" },
            new Country { Id = 3, Name = "United States" }
        };

        public List<Country> SelectedCountries { get; set; } = new List<Country>();
    }
}

using System.Collections.Generic;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample2
{
    public class Country
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<string> Cities { get; set; } = new List<string>();
        public bool IsEnabled { get; set; } = true;
        public bool IsChecked { get; set; }
    }
}

Sample 3: Working with Objects 2

To make the SelectedValues property contain only some values from the DataSource objects (like the Id property of the object), you may use the ItemValueBinding property.

The SelectedValues will then contain only the values of the properties specified in the ItemValueBinding. Provided the values of the properties used as a value are unique, you don't need to specify the ItemKeyBinding property.

The ItemKeyBinding property is required only when the control cannot compare the objects in the DataSource collection with the objects in the SelectedValues. If the ItemValueBinding is set and makes the SelectedValues collection use primitive types that can be compared, the ItemKeyBinding property is not needed. Similarly, if the DataSource collection contains only primitive values (string, int etc.), the ItemKeyBinding property is not necessary.

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                ItemValueBinding="{value: Id}"
                ItemTextBinding="{value: Name}"
                Placeholder="Select multiple countries"
                Changed="{command: PrintSummary()}" />

<p>Selected Countries: {{value: Summary}}</p>

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample3
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<Country> Countries { get; set; } = new List<Country> {
            new Country { Id = 1, Name = "Czech Republic" },
            new Country { Id = 2, Name = "Slovakia" },
            new Country { Id = 3, Name = "United States" }
        };

        public List<int> SelectedCountries { get; set; } = new List<int>();
        public string Summary { get; set; }

        public void PrintSummary()
        {
            Summary = string.Join(", ", SelectedCountries.Select(c => c.ToString()));
        }
    }
}

using System.Collections.Generic;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample3
{
    public class Country
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<string> Cities { get; set; } = new List<string>();
        public bool IsEnabled { get; set; } = true;
        public bool IsChecked { get; set; }
    }
}

Sample 4: Item Templates

To display custom content in the list items, you can use the ItemTemplate property to declare a custom template for the list items.

<bp:MultiSelect DataSource="{value: Cities}"
                SelectedValues="{value: SelectedCities}"
                ItemKeyBinding="{value: Id}"
                ItemTextBinding="{value: Name}"
                Placeholder="Select multiple cities">
    <ItemTemplate>
        <span>{{value: Name}}, {{value: Country}}</span>
    </ItemTemplate>
</bp:MultiSelect>

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample4
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<City> Cities { get; set; } = new List<City> {
            new City { Id = 1, Name = "Prague", Country = "Czech Republic" },
            new City { Id = 2, Name = "Bratislava", Country = "Slovakia" }
        };

        public List<City> SelectedCities { get; set; } = new List<City>();
    }
}

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample4
{
    public class City
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Country { get; set; }
    }
}

Sample 5: Changed Event

The Changed event is triggered whenever the selection changes.

page.dothtml
ViewModel.cs

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                Placeholder="Select multiple countries"
                Changed="{command: SelectionChanged()}" />

<p>You've selected {{value: SelectedCountriesCount}} countries.</p>

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample5
{
    public class ViewModel : DotvvmViewModelBase
    {
        public int SelectedCountriesCount { get; set; }

        public List<string> Countries { get; set; } = new List<string> {
            "Czech Republic", "Slovakia", "United States"
        };

        public List<string> SelectedCountries { get; set; } = new List<string>();

        public void SelectionChanged()
        {
            SelectedCountriesCount = SelectedCountries.Count;
        }
    }
}

Sample 6: New Items

To allow entering a custom value which is not present in the DataSource collection, you can use the AllowNewItems property.

The Text property contains the exact value the user entered in the text field.

This feature can be used only when the DataSource collection contains string values.

page.dothtml
ViewModel.cs

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                AllowNewItems="true"
                Placeholder="Select or type multiple countries" />

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample6
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<string> Countries { get; set; } = new List<string> {
            "Czech Republic", "Slovakia", "United States"
        };

        public List<string> SelectedCountries { get; set; } = new List<string>();
    }
}

Sample 7: Server Search

The LoadItems property can specify a command in the viewmodel which will return new items based on what the user types in the control. Typically, this method is used with the Static Command and the method should return a list of items, and you need to use the value of the Text property as an argument to the viewmodel method.

The method in the viewmodel performs the search and returns a collection of items. These items are either added to existing items in the DataSource collection or they replace the existing items. It depends on the LoadItemsMode property.

If you use the static command, don't forget to decorate the method with the AllowStaticCommand attribute.

In the future versions of DotVVM, there are plans to enhance the server search functionality with more features (e.g. REST API integration).

page.dothtml
ViewModel.cs

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                Text="{value: Text}"
                LoadItems="{staticCommand: LoadCountries(Text)}"
                Placeholder="Search and select multiple countries" />

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample7
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string Text { get; set; }
        public List<string> Countries { get; set; } = new List<string>();
        public List<string> SelectedCountries { get; set; } = new List<string>();

        [AllowStaticCommand]
        public IEnumerable LoadCountries(string searchText)
        {
            return new List<string> {
                $"{searchText} 1", $"{searchText} 2", $"{searchText} 3"
            };
        }
    }
}

Sample 8: Item Keys

The ItemKeyBinding property must be used when the SelectedValue is not a primitive type (like string, int etc.), or when the ItemValueBinding is not specified. This property helps the control to uniquely identify the selected object.

<bp:MultiSelect DataSource="{value: Cities}"
                SelectedValues="{value: SelectedCities}"
                ItemKeyBinding="{value: Id}"
                ItemTextBinding="{value: Name}"
                Placeholder="Select multiple cities">
    <ItemTemplate>
        <span>{{value: Name}}, {{value: Country}}</span>
    </ItemTemplate>
</bp:MultiSelect>

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

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample8
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<City> Cities { get; set; } = new List<City> {
            new City { Id = 1, Name = "Salt Lake City", Country = "Utah" },
            new City { Id = 2, Name = "Wichita", Country = "Kansas" },
            new City { Id = 3, Name = "Atlanta", Country = "Georgia" }
        };

        public List<City> SelectedCities { get; set; } = new List<City>();
    }
}

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample8
{
    public class City
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Country { get; set; }
    }
}

Sample 9: Customizing Icons

The icon used by the control can be customized using the following inner elements:

UnselectIcon represents an icon that allows the user to deselect items. The default is Close icon.

See the Icon documentation to find about using other icon packs.

page.dothtml
ViewModel.cs

<bp:MultiSelect DataSource="{value: Countries}"
                SelectedValues="{value: SelectedCountries}"
                Placeholder="Select multiple countries" >
    <UnselectIcon>
        <bp:Icon Icon="Minus"></bp:Icon>
    </UnselectIcon>
</bp:MultiSelect>

using System.Collections.Generic;
using DotVVM.BusinessPack.Controls;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.MultiSelect.sample9
{
    public class ViewModel : DotvvmViewModelBase
    {
        public List<string> Countries { get; set; } = new List<string> {
            "Czech Republic", "Slovakia", "United States"
        };

        public List<string> SelectedCountries { get; set; } = new List<string>();
    }
}

Show all inherited properties

Properties

Name	Type	Description	Notes	Default Value
AllowNewItems	Boolean	Gets or sets whether it is allowed to create new items from the entered text.	attribute inner element static value bindable default	False
AutoFocus	Boolean	Gets or sets whether the control should have focus when page loads or when a dialog is opened. The default value is false.	attribute inner element static value bindable default	False
ClientIDMode	ClientIDMode	Gets or sets the client ID generation algorithm.	attribute inner element static value bindable default	Static
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. The DataContext is null in client-side templates.	attribute inner element static value bindable default	null
DataSource	IEnumerable	Gets or sets the data source containing data for this control.	attribute inner element static value bindable default	null
Enabled	Boolean	Gets or sets whether the control is enabled and can be modified.	attribute inner element static value bindable default	True
ID	String	Gets or sets the control client ID within its naming container.	attribute inner element static value bindable default	null
IncludeInPage	Boolean	Gets or sets whether the control is included in the DOM of the page.	attribute inner element static value bindable default	True
InnerText	String	Gets or sets the inner text of the HTML element. Note that this property can only be used on HtmlGenericControl directly and when the control does not have any children.	attribute inner element static value bindable default	null
ItemEnabledBinding	IValueBinding<Boolean?>	Gets or sets the binding indicating whether a data item can be selected.	attribute inner element static value bindable default	null
ItemKeyBinding	IValueBinding	Gets or sets the binding which retrieves the unique key of a data item.	attribute inner element static value bindable default	null
ItemTemplate	ITemplate	Gets or sets the template used to render each data item.	attribute inner element static value bindable default	null
ItemTextBinding	IValueBinding<String>	Gets or sets the binding which retrieves the text from a data item. It retrieves the whole item by default.	attribute inner element static value bindable default	null
ItemValueBinding	IValueBinding	Gets or sets the binding which retrieves a value from a data item. It retrieves the whole item by default.	attribute inner element static value bindable default	null
LoadItems	MultiSelect+LoadItemsFunc	Gets or sets a function used to load additional items from server. For example, it is used to search for items on server-side.	attribute inner element static value bindable default	null
LoadItemsMode	LoadItemsMode	Gets or sets how are items returned by the LoadItems command processed. They can either be merged with existing items in the DataSource; or they can replace them. The default value is Merge.	attribute inner element static value bindable default	Merge
Placeholder	String	Gets or sets the text displayed when no item is selected (or when text is empty).	attribute inner element static value bindable default	null
SelectedValues	IEnumerable	Gets or sets values of the items selected by user.	attribute inner element static value bindable default	null
SelectedValueTemplate	ITemplate	Gets or sets the template for each MultiSelect value.	attribute inner element static value bindable default	null
TabIndex	Int32	Gets or sets the order in which the control is reachable in sequential keyboard navigation. The default value is 0 which means the document order.	attribute inner element static value bindable default	0
UnselectIcon	IconBase	Gets or sets the icon displayed on the unselect button.	attribute inner element static value bindable default	null
Visible	Boolean	Gets or sets whether the control is visible. When set to false, `style="display: none"` will be added to this control.	attribute inner element static value bindable default	True

Events

	Name	Type	Description
	Changed	Command	Gets or sets the command triggered when the text (or value) is changed.
	NewItemAdded	Command	Gets or sets the command that should be called after new item is being added when AllowNewItems is true.

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