Implementing Syncfusion WPF ComboBox (ComboBoxAdv)

Comprehensive guide for implementing the Syncfusion® WPF ComboBoxAdv control, a powerful dropdown component that allows users to type a value or choose options from a list with support for multiselection, editing, autocomplete, data binding, and advanced features.

When to Use This Skill

Use this skill when you need to:

• Implement dropdown selection in WPF applications
• Enable multiselection with checkboxes or tokens
• Add editable dropdowns with autocomplete functionality
• Bind data to dropdown controls using MVVM patterns
• Customize item display with templates
• Configure watermarks (default text) for user prompts
• Set custom delimiters for multiselect displays
• Integrate with Expression Blend for design-time editing
• Apply themes using SfSkinManager or ThemeStudio

Component Overview

The ComboBoxAdv control (Syncfusion.Windows.Tools.Controls.ComboBoxAdv) extends standard WPF dropdown functionality with:

Key Features:

• Multiselection with checkboxes, tokens, OK/Cancel buttons
• Editable mode with autocomplete (suggest mode)
• Data binding via ItemsSource with DisplayMemberPath
• Token display for selected items with close icons
• Watermark support (DefaultText property)
• Custom delimiters for multiselect display
• Item templates for complex UI
• Theme support with built-in and custom themes
• Expression Blend integration for design-time editing

Namespace: Syncfusion.Windows.Tools.Controls Assembly: Syncfusion.Shared.WPF Schema: http://schemas.syncfusion.com/wpf

Documentation and Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• Installation and assembly deployment
• Adding control via designer, XAML, and C#
• Creating data models and ViewModels
• Basic data binding patterns
• DisplayMemberPath configuration
• ItemTemplate customization
• Theme setup and application

Selection and MultiSelection

📄 Read: references/selection-multiselection.md

• Single selection (SelectedItem, SelectedIndex, SelectedValue)
• Enabling multiselection (AllowMultiSelect)
• Programmatic selection with SelectedItems
• SelectAll functionality
• OK/Cancel buttons for multiselect
• Overriding OnItemChecked/OnItemUnchecked
• Token support (EnableToken) for visual item representation
• Token editing and keyboard access
• SelectionChanged event handling

Editing and AutoComplete

📄 Read: references/editing-autocomplete.md

• IsEditable property for text input
• AutoComplete modes (Suggest, None)
• Filtering dropdown items dynamically
• Editable mode with token support
• Text search and item matching

Watermark and Delimiter

📄 Read: references/watermark-delimiter.md

• DefaultText property for watermarks
• SelectedValueDelimiter customization
• Usage patterns and best practices

Data Binding

📄 Read: references/data-binding.md

• ItemsSource binding fundamentals
• Creating MVVM-compatible models and ViewModels
• DisplayMemberPath vs ItemTemplate
• ObservableCollection patterns
• Two-way binding with SelectedItems
• INotifyPropertyChanged implementation

Customization and Blendability

📄 Read: references/customization-blendability.md

• Expression Blend workflow
• Style editing and template customization
• Theme application with SfSkinManager
• Creating custom themes with ThemeStudio
• Control appearance customization

Quick Start

Basic ComboBoxAdv with Static Items

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:syncfusion="http://schemas.syncfusion.com/wpf">
    <Grid>
        <syncfusion:ComboBoxAdv Height="30" Width="200"
                                HorizontalAlignment="Center"
                                VerticalAlignment="Center">
            <syncfusion:ComboBoxItemAdv Content="Denmark" />
            <syncfusion:ComboBoxItemAdv Content="New Zealand" />
            <syncfusion:ComboBoxItemAdv Content="Canada" />
            <syncfusion:ComboBoxItemAdv Content="Russia" />
            <syncfusion:ComboBoxItemAdv Content="Japan" />
        </syncfusion:ComboBoxAdv>
    </Grid>
</Window>

Data-Bound ComboBoxAdv with MVVM

// Model
public class Country
{
    public string Name { get; set; }
    public string Code { get; set; }
}

// ViewModel
public class ViewModel : INotifyPropertyChanged
{
    private ObservableCollection<Country> countries;
    public ObservableCollection<Country> Countries
    {
        get { return countries; }
        set { countries = value; OnPropertyChanged(nameof(Countries)); }
    }

    public ViewModel()
    {
        Countries = new ObservableCollection<Country>
        {
            new Country { Name = "Denmark", Code = "DK" },
            new Country { Name = "New Zealand", Code = "NZ" },
            new Country { Name = "Canada", Code = "CA" }
        };
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string name) =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}

<Window.DataContext>
    <local:ViewModel />
</Window.DataContext>
<syncfusion:ComboBoxAdv ItemsSource="{Binding Countries}"
                        DisplayMemberPath="Name"
                        Height="30" Width="200"/>

Common Patterns

Pattern 1: Multiselection with Tokens

<syncfusion:ComboBoxAdv AllowMultiSelect="True"
                        IsEditable="True"
                        EnableToken="True"
                        ItemsSource="{Binding Items}"
                        DisplayMemberPath="Name"
                        Height="Auto" Width="300"/>

Pattern 2: Editable with AutoComplete

<syncfusion:ComboBoxAdv IsEditable="True"
                        AutoCompleteMode="Suggest"
                        ItemsSource="{Binding Items}"
                        DisplayMemberPath="Name"
                        Height="30" Width="200"/>

Pattern 3: Watermark with Delimiter

<syncfusion:ComboBoxAdv AllowMultiSelect="True"
                        DefaultText="Select items..."
                        SelectedValueDelimiter=" | "
                        ItemsSource="{Binding Items}"
                        DisplayMemberPath="Name"
                        Height="30" Width="300"/>

Pattern 4: Multiselect with OK/Cancel

<syncfusion:ComboBoxAdv AllowMultiSelect="True"
                        AllowSelectAll="True"
                        EnableOKCancel="True"
                        ItemsSource="{Binding Items}"
                        DisplayMemberPath="Name"
                        Height="30" Width="250"/>

Key Properties

Common Use Cases

1. Country/Region Selector - Single selection with data binding
2. Tag Selector - Multiselection with tokens for visual feedback
3. Searchable Dropdown - Editable with autocomplete for large lists
4. Category Filter - Multiselection with delimiters
5. Form Input with Prompt - Watermark text for user guidance
6. Bulk Selection - Select All with OK/Cancel for confirmation

See Also

• Syncfusion WPF ComboBoxAdv Documentation
• WPF ComboBoxAdv API Reference