Syncfusion Aspnetcore Dropdowns

Implementing Syncfusion ASP.NET Core Dropdowns

DropDownList

The DropDownList (<ejs-dropdownlist>) is a single-selection control that displays a list of predefined values. It supports local and remote data binding, real-time filtering, grouping, custom templates, virtual scrolling, popup resize, localization, and full WCAG 2.2 AA accessibility.

Component Overview

Tag Helper: <ejs-dropdownlist>
Namespace: Syncfusion.EJ2.DropDowns
NuGet: Syncfusion.EJ2.AspNet.Core

Key Features:

• Data binding from local arrays and remote sources (OData V4, Web API, URL Adaptor)
• Value binding for primitive types and complex objects (allowObjectBinding)
• Real-time filtering with search box (allowFiltering, filterType, debounceDelay)
• Grouping items using fields.groupBy
• Disabled items using fields.disabled
• Customizable templates: itemTemplate, valueTemplate, headerTemplate, footerTemplate, groupTemplate, noRecordsTemplate, actionFailureTemplate
• Virtual scrolling for large datasets (enableVirtualization)
• Popup resize by user (allowResize)
• WCAG 2.2 AA compliance, keyboard navigation, ARIA support
• RTL rendering (enableRtl)
• Localization (locale)
• Float label support (floatLabelType)
• State persistence (enablePersistence)
• Clear button (showClearButton)

API Reference

📄 Full API: references/api.md

• All properties with types, defaults, and descriptions
• All events
• Field settings (<e-dropdownlist-fields>)
• Tag helper syntax examples for all features

Documentation and Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• NuGet package installation
• TagHelper registration (_ViewImports.cshtml)
• ⚠️ CDN vs. Local Hosting: See Security & Trust Boundary below for SRI and local hosting alternatives
• Script Manager registration
• Basic DropDownList tag helper usage
• Popup height/width configuration
• Change event handling

Data Binding and Value Binding

📄 Read: references/data-binding.md

• Binding array of primitive data (strings, numbers)
• Binding complex JSON objects with <e-dropdownlist-fields>
• Nested/complex data with dot-notation field paths
• Value binding for primitive types (pre-selecting)
• Object binding with allowObjectBinding
• Remote data: OData V4, OData, Web API, URL Adaptor
• Offline mode (DataManager offline="true")
• actionBegin, actionComplete, actionFailure events

Filtering and Grouping

📄 Read: references/filtering-grouping.md

• Enable filtering with allowFiltering
• Filter types: StartsWith, Contains, EndsWith
• Minimum character limit before remote request
• Case-sensitive filtering with ignoreCase
• Diacritics filtering with ignoreAccent
• Debounce delay with debounceDelay
• Filter bar placeholder with filterBarPlaceholder
• Grouping with fields.groupBy
• Custom group header with groupTemplate
• Disabled items with fields.disabled
• Sort order: None, Ascending, Descending

Templates and Styling

📄 Read: references/templates-styling.md

• itemTemplate — customize popup list items
• valueTemplate — customize selected value in input
• headerTemplate — static header in popup
• footerTemplate — static footer in popup
• groupTemplate — custom group headers
• noRecordsTemplate — no data state
• actionFailureTemplate — remote fetch failure state
• floatLabelType — float label behavior
• cssClass — custom CSS class
• CSS structures for appearance customization

Accessibility and Localization

📄 Read: references/accessibility-features.md

• WCAG 2.2 Level AA compliance
• WAI-ARIA attributes (aria-haspopup, aria-expanded, aria-selected, etc.)
• Full keyboard navigation shortcut reference
• RTL support with enableRtl
• Localization with locale and L10n.load()
• Readonly vs disabled states
• enablePersistence for state persistence
• isDeviceFullScreen for mobile popup behavior

Advanced Scenarios

📄 Read: references/advanced-scenarios.md

• Virtual scrolling with enableVirtualization (local and remote)
• Virtualization with grouping and filtering
• Customizing item count in virtualization
• Popup resize with allowResize, resizeStart, resizeStop, resizing events
• Cascading dropdowns (parent-child dependent selection)
• Remote data with filtering
• Pre-selecting values (by value, text, or index)
• showClearButton usage
• htmlAttributes for extra HTML attributes
• All events reference with usage examples

Quick Start Example

Controller (HomeController.cs):

public IActionResult Index()
{
    ViewBag.data = new List<object>
    {
        new { Id = 1, Name = "Electronics" },
        new { Id = 2, Name = "Furniture" },
        new { Id = 3, Name = "Clothing" }
    };
    return View();
}

View (Index.cshtml):

<ejs-dropdownlist id="category"
    dataSource="@ViewBag.data"
    placeholder="Select category"
    change="onCategoryChange">
    <e-dropdownlist-fields text="Name" value="Id"></e-dropdownlist-fields>
</ejs-dropdownlist>

<script>
function onCategoryChange(args) {
    console.log('Selected ID:', args.value);
}
</script>

Common Patterns

Pattern 1: Basic Selection with Event Handling

<ejs-dropdownlist id="category"
    dataSource="@ViewBag.Categories"
    placeholder="Select category"
    change="onCategoryChange">
    <e-dropdownlist-fields text="Name" value="Id"></e-dropdownlist-fields>
</ejs-dropdownlist>

<script>
function onCategoryChange(args) {
    console.log('Selected ID:', args.value);
}
</script>

Pattern 2: Cascading Dropdowns (Secure Server-Side Proxy)

⚠️ Security Note: Avoid client-side direct fetch to untrusted external endpoints. Use a server-side proxy that validates, authenticates, and sanitizes responses.

Controller (Server-Side Proxy):

public IActionResult Index()
{
    ViewBag.Countries = new List<Country>
    {
        new Country { Id = 1, Name = "USA" },
        new Country { Id = 2, Name = "Canada" }
    };
    return View();
}

// ✅ SECURE: Server-side proxy validates countryId and returns only whitelisted data
[HttpGet("api/cities/{countryId}")]
public IActionResult GetCities(int countryId)
{
    // Validate countryId is within acceptable range
    if (countryId <= 0 || countryId > 100)
        return BadRequest("Invalid country ID");
    
    var cities = new List<City>
    {
        new City { Id = 1, Name = "New York",  CountryId = 1 },
        new City { Id = 2, Name = "Toronto",   CountryId = 2 }
    };
    
    // Return only safe, schema-validated data
    return Json(cities.Where(c => c.CountryId == countryId)
        .Select(c => new { c.Id, c.Name })
        .ToList());
}

View (Secure Client):

<ejs-dropdownlist id="Country"
    dataSource="@ViewBag.Countries"
    change="onCountryChange"
    placeholder="Select country">
    <e-dropdownlist-fields text="Name" value="Id"></e-dropdownlist-fields>
</ejs-dropdownlist>

<ejs-dropdownlist id="City" placeholder="Select city">
    <e-dropdownlist-fields text="Name" value="Id"></e-dropdownlist-fields>
</ejs-dropdownlist>

<script>
function onCountryChange(args) {
    var cityDDL = document.getElementById('City').ej2_instances[0];
    if (args.value) {
        // ✅ SECURE: Fetch only from same-origin API endpoint (same server)
        fetch("/api/cities/" + encodeURIComponent(args.value), {
            method: 'GET',
            headers: { 'Content-Type': 'application/json' },
            credentials: 'same-origin'  // Include CSRF tokens via cookies
        })
        .then(response => {
            if (!response.ok) throw new Error('Server error: ' + response.status);
            return response.json();
        })
        .then(data => {
            // Validate response is an array before binding
            if (Array.isArray(data)) {
                cityDDL.dataSource = data;
                cityDDL.value = null;
            } else {
                console.error('Invalid data format received');
                cityDDL.dataSource = [];
            }
        })
        .catch(error => {
            console.error('Failed to load cities:', error);
            cityDDL.dataSource = [];
        });
    } else {
        cityDDL.dataSource = [];
    }
}
</script>

Pattern 3: Remote Data with Filtering (Secure Same-Origin Proxy)

⚠️ Security Note: Avoid crossDomain="true" and direct binding to external OData/WebAPI endpoints. Always proxy through your own server to control validation and access.

<!-- ✅ SECURE: Remove crossDomain, use same-origin server proxy -->
<ejs-dropdownlist id="customers"
    allowFiltering="true"
    filtering="onfiltering"
    query="new ej.data.Query().from('api/customers').select(['ContactName', 'CustomerID']).take(6)"
    placeholder="Select a customer"
    popupHeight="200px">
    <e-dropdownlist-fields text="ContactName" value="CustomerID"></e-dropdownlist-fields>
    <e-data-manager url="/api/customers"
                    adaptor="UrlAdaptor">  <!-- UrlAdaptor for same-origin JSON endpoint -->
    </e-data-manager>
</ejs-dropdownlist>

<script>
function onfiltering(e) {
    var ddl = document.getElementById("customers").ej2_instances[0];
    var query = new ej.data.Query().from('api/customers').select(['ContactName', 'CustomerID']).take(6);
    query = e.text !== '' ? query.where('ContactName', 'startswith', e.text, true) : query;
    e.updateData(ddl.dataSource, query);
}
</script>

Controller (Server-Side Proxy):

// ✅ SECURE: Server validates, filters, and returns safe subset of data
[HttpGet("api/customers")]
public IActionResult GetCustomers([FromQuery] string skip = "0", [FromQuery] string take = "6", [FromQuery] string where = "")
{
    int skipVal = Math.Max(0, int.TryParse(skip, out var s) ? s : 0);
    int takeVal = Math.Min(50, int.TryParse(take, out var t) && t > 0 ? t : 6);
    
    // Example: fetch from secure internal data source
    var customers = _context.Customers
        .AsNoTracking()
        .Select(c => new { c.CustomerID, c.ContactName })
        .Skip(skipVal)
        .Take(takeVal)
        .ToList();
    
    return Ok(new { d = customers, count = customers.Count });
}

Key Properties and When to Use

Next Steps

• Just starting? → Getting Started
• Binding server data? → Data Binding
• Need filtering or grouping? → Filtering and Grouping
• Customizing appearance? → Templates and Styling
• Accessibility or localization? → Accessibility and Localization
• Virtual scroll, resize, cascading? → Advanced Scenarios
• Complete API reference? → API Reference

MultiSelect Dropdown

The Syncfusion MultiSelect Dropdown is a powerful component for selecting multiple values from a predefined list. It supports checkbox selection, filtering, grouping, templates, virtual scrolling, and rich data binding — all using ASP.NET Core TagHelper syntax.

Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• NuGet package installation and TagHelper setup
• CDN stylesheet and script references
• First MultiSelect with basic configuration
• Popup height/width configuration
• Form integration and MultiSelectFor

Data Binding & Value Binding

📄 Read: references/data-binding.md

• Binding array of strings, objects, and complex data
• Remote data: OData, WebAPI, URL Adaptor, offline mode
• Fields mapping (text, value, groupBy, iconCss, disabled)
• Primitive vs object value binding (allowObjectBinding)
• Preselecting values via value property
• Using isSelected field to preselect via data source

Checkbox & Selection Modes

📄 Read: references/checkbox-and-selection.md

• Checkbox mode with CheckBoxSelection module
• Select All / Unselect All with showSelectAll
• Customizing "Select All" and "Unselect All" text
• Maximum selection limit (maximumSelectionLength)
• Selection reordering (enableSelectionOrder)
• Display modes: Default, Box, Delimiter, CheckBox
• closePopupOnSelect behavior
• hideSelectedItem to remove selected items from list
• changeOnBlur for event timing control

Filtering

📄 Read: references/filtering.md

• Enabling filtering with allowFiltering
• Filter types: StartsWith, Contains, EndsWith
• Minimum character threshold before remote fetch
• Case-sensitive filtering
• Diacritics / accent-insensitive filtering (ignoreAccent)
• Debounce delay (debounceDelay)
• Custom filtering logic via filtering event

Templates & Customization

📄 Read: references/templates-and-customization.md

• Item template for custom list item layout
• Value template for selected chip display
• Group template for category headers
• Header and footer templates
• No records template and action failure template
• Chip customization via tagging event and setClass
• CSS customization for wrapper, chips, icons, popup
• Icon support via iconCss field

Grouping & Virtualization

📄 Read: references/grouping-and-virtualization.md

• Grouping items using groupBy field
• Grouping with checkboxes (enableGroupCheckBox)
• Virtual scrolling for large datasets (enableVirtualization)
• Virtualization with remote data, grouping, filtering, checkboxes
• Preselecting values with virtualization
• Custom item count in virtualization

Advanced Features

📄 Read: references/advanced-features.md

• Custom value entry (allowCustomValue)
• Disabled items via fields.disabled
• disableItem method for dynamic disabling
• Popup resize (allowResize)
• Localization (locale, L10n translations)
• Accessibility (WCAG 2.2, keyboard navigation, ARIA)
• Sorting (sortOrder)
• Right-to-left support (enableRtl)
• State persistence (enablePersistence)
• addTagOnBlur behavior
• openOnClick configuration

API Reference

📄 Read: references/api.md

• Complete properties reference with types and defaults
• All events with descriptions
• FieldSettings sub-properties
• TagHelper attribute naming conventions

Quick Start Example

@* _ViewImports.cshtml: @addTagHelper *, Syncfusion.EJ2 *@

@{
    var games = new List<object> {
        new { Id = 1, Game = "Football" },
        new { Id = 2, Game = "Basketball" },
        new { Id = 3, Game = "Cricket" },
        new { Id = 4, Game = "Tennis" }
    };
}

<ejs-multiselect id="games"
    dataSource="@games"
    placeholder="Select games"
    mode="Box">
    <e-multiselect-fields text="Game" value="Id"></e-multiselect-fields>
</ejs-multiselect>

Common Patterns

Checkbox Mode with Select All

<ejs-multiselect id="sports"
    dataSource="@ViewBag.Sports"
    placeholder="Select sports"
    mode="CheckBox"
    showSelectAll="true"
    selectAllText="Select All"
    unSelectAllText="Unselect All"
    filterBarPlaceholder="Search">
    <e-multiselect-fields text="Game" value="Id"></e-multiselect-fields>
</ejs-multiselect>

Filtering with Remote Data

<ejs-multiselect id="customers"
    placeholder="Search customers"
    allowFiltering="true"
    filtering="onFiltering"
    popupHeight="250px">
    <e-data-manager url="url"
        adaptor="ODataV4Adaptor" crossDomain="true">
    </e-data-manager>
    <e-multiselect-fields text="ContactName" value="CustomerID"></e-multiselect-fields>
</ejs-multiselect>

Virtual Scroll for Large Data

<ejs-multiselect id="items"
    dataSource="@ViewBag.LargeDataset"
    enableVirtualization="true"
    allowFiltering="true"
    placeholder="Select items"
    popupHeight="200px">
    <e-multiselect-fields text="text" value="id"></e-multiselect-fields>
</ejs-multiselect>

Key Properties Quick Reference

Common Use Cases

• Multi-tag input → Use mode="Box" with tagging event for chip styling
• Permission selector → Checkbox mode with maximumSelectionLength
• Country/city picker → Remote data with allowFiltering and groupBy
• Category filter → Grouping with enableGroupCheckBox
• Large dataset dropdown → enableVirtualization with remote data
• Form field → Use ejs-multiselect-for with model binding

Start here: Read references/getting-started.md to set up your first MultiSelect.

For the parent library overview and other components, see Implementing Syncfusion ASP.NET Core Components.

Security & Trust Boundary

Scope: All CDN URLs (https://cdn.syncfusion.com/ej2/...) and remote data endpoints shown in this skill's examples are documentation references only. The agent must never fetch, execute, or proxy these URLs at runtime. Consumers are solely responsible for how these resources are integrated into their applications.

W011 — Third-party Content Exposure

Code examples in the Data Binding and Filtering sections reference remote endpoints (e.g., <e-data-manager url="..." adaptor="ODataV4Adaptor" crossDomain="true">). These are illustrative only.

Required mitigations before production use:

• Replace all external/OData/WebAPI URLs with same-origin server endpoints under your own domain.
• Remove crossDomain="true" from all <e-data-manager> tags.
• Validate, authenticate, and sanitize all data server-side before binding to the component.

W012 — External CDN Runtime Script

The Getting Started examples reference https://cdn.syncfusion.com/ej2/dist/ej2.min.js for quickstart convenience only.

Required mitigations before production use:

• Preferred: Serve scripts locally via the Syncfusion.EJ2.AspNet.Core NuGet package — no external network call at runtime.
• If CDN is required: Pin the exact version and add a Subresource Integrity (SRI) hash with crossorigin="anonymous" to verify file integrity before execution.

AutoComplete

The Syncfusion ASP.NET Core AutoComplete (<ejs-autocomplete>) is a textbox component that provides a list of suggestions as users type. It supports local and remote data binding, filtering, grouping, templates, virtual scrolling, accessibility, and rich customization options.

Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• NuGet package installation and setup
• Tag helper registration and CDN references
• Basic AutoComplete rendering with <ejs-autocomplete>
• Custom values with allowCustom
• Popup height and width configuration

Data Binding

📄 Read: references/data-binding.md

• Binding array of strings and array of objects
• Binding complex/nested object data
• Remote data binding (OData, OData V4, Web API, URL Adaptor)
• Offline mode with DataManager
• Fields mapping (value, groupBy, iconCss)

Filtering

📄 Read: references/filtering.md

• Filter types: StartsWith, EndsWith, Contains
• Limiting suggestion count with suggestionCount
• Minimum character length with minLength
• Case-sensitive filtering with ignoreCase
• Diacritics/accent-insensitive filtering with ignoreAccent
• Debounce delay to reduce filtering frequency

Grouping

📄 Read: references/grouping.md

• Grouping list items by category using groupBy field
• Inline and fixed group headers
• Custom group header with groupTemplate

Templates

📄 Read: references/templates.md

• Item template (itemTemplate) for custom list item content
• Group template (groupTemplate) for group headers
• Header template (headerTemplate) for static popup header
• Footer template (footerTemplate) for static popup footer
• No records template (noRecordsTemplate)
• Action failure template (actionFailureTemplate)

Value Binding

📄 Read: references/value-binding.md

• Binding primitive values (string, number, boolean) with value
• Object binding with allowObjectBinding
• Pre-selecting values

Virtual Scrolling

📄 Read: references/virtual-scroll.md

• Enable virtualization with enableVirtualization
• Virtual scrolling with local data
• Virtual scrolling with remote data
• Customizing item count in virtualization
• Grouping with virtualization

Disabled Items & Component State

📄 Read: references/disabled-items.md

• Disabling individual items with fields.disabled
• Using disableItem method dynamically
• Disabling the entire component with enabled

Localization

📄 Read: references/localization.md

• Localizing noRecordsTemplate and actionFailureTemplate
• Loading translations with L10n
• Setting locale with locale property

Popup Resizing

📄 Read: references/resize.md

• Enabling resizable popup with allowResize
• Resize persistence across sessions

Styling & CSS Customization

📄 Read: references/style.md

• Customizing wrapper, icon, focus, placeholder, text selection
• Customizing popup item appearance
• Outline theme and float label customization

Accessibility

📄 Read: references/accessibility.md

• WCAG 2.2, Section 508, screen reader support
• WAI-ARIA attributes and roles
• Full keyboard navigation shortcuts

How-To Scenarios

📄 Read: references/how-to.md

• Autofill (auto-complete while typing with autofill)
• Custom highlight search (highlight property)
• Show list items with icons (iconCss)
• Filter by both text and value fields
• AutoCompleteFor with model binding and data annotations

API Reference

📄 Read: references/api.md

• Complete list of all properties, events, and their default values
• Properties: actionFailureTemplate, allowCustom, allowObjectBinding, allowResize, autofill, cssClass, dataSource, debounceDelay, enabled, enablePersistence, enableRtl, enableVirtualization, fields, filterType, floatLabelType, footerTemplate, groupTemplate, headerTemplate, highlight, htmlAttributes, ignoreAccent, ignoreCase, isDeviceFullScreen, itemTemplate, locale, minLength, noRecordsTemplate, placeholder, popupHeight, popupWidth, query, readonly, showClearButton, showPopupButton, sortOrder, suggestionCount, value, width, zIndex
• Events: actionBegin, actionComplete, actionFailure, beforeOpen, blur, change, close, created, customValueSpecifier, dataBound, destroyed, filtering, focus, open, resizeStart, resizeStop, resizing, select

Quick Start

Basic AutoComplete (array of strings):

@{
    var sports = new string[] { "Badminton", "Basketball", "Cricket", "Football", "Golf", "Hockey", "Tennis" };
}

<ejs-autocomplete id="sports" dataSource="sports" placeholder="Select a sport">
</ejs-autocomplete>

AutoComplete with object data source:

@{
    List<Countries> countries = new List<Countries> {
        new Countries { Name = "India", Code = "IN" },
        new Countries { Name = "United States", Code = "US" },
        new Countries { Name = "Germany", Code = "DE" }
    };
}

<ejs-autocomplete id="country" dataSource="@countries" placeholder="Select a country">
    <e-autocomplete-fields value="Name"></e-autocomplete-fields>
</ejs-autocomplete>

Model class:

public class Countries {
    public string Name { get; set; }
    public string Code { get; set; }
}

Common Patterns

Remote Data with OData

<ejs-autocomplete id="customers"
    query="new ej.data.Query().from('Customers').select(['ContactName'])"
    placeholder="Find a customer"
    filterType="StartsWith"
    popupHeight="200px">
    <e-autocomplete-fields value="ContactName"></e-autocomplete-fields>
    <e-data-manager url="url"
        adaptor="ODataV4Adaptor" crossDomain="true">
    </e-data-manager>
</ejs-autocomplete>

Grouped List with Custom Filter

<ejs-autocomplete id="vegetables"
    dataSource="@vegList"
    placeholder="Select a vegetable"
    filterType="StartsWith"
    suggestionCount="10"
    minLength="1">
    <e-autocomplete-fields value="Vegetable" groupBy="Category"></e-autocomplete-fields>
</ejs-autocomplete>

Virtual Scrolling for Large Data

<ejs-autocomplete id="records"
    dataSource="@data"
    placeholder="e.g. Item 1"
    enableVirtualization="true"
    popupHeight="200px">
    <e-autocomplete-fields value="Text"></e-autocomplete-fields>
</ejs-autocomplete>

Key Properties Quick Reference

Mention

The Syncfusion ASP.NET Core Mention (<ejs-mention>) is an inline suggestion component that listens to a target element (a contenteditable div or textarea) and displays a suggestion popup when the user types a trigger character (default: @). It supports local and remote data binding, custom templates, configurable filtering, sorting, disabled items, and full accessibility.

Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• NuGet package installation and project setup
• Tag helper registration (@addTagHelper *, Syncfusion.EJ2)
• CDN stylesheet and script references
• Script manager registration (<ejs-scripts>)
• Defining the target contenteditable element
• Basic Mention rendering with <ejs-mention>
• Binding a string array as data source
• Displaying the mention character with showMentionChar and mentionChar

Data Binding

📄 Read: references/data-binding.md

• Binding simple string arrays
• Binding arrays of JSON objects with <e-mention-fields>
• Binding complex/nested object data with dot-notation field mapping
• Remote data binding with OData V4 adaptor
• Remote data binding with Web API adaptor
• Using <e-data-manager> for remote sources
• query property for customizing remote fetch requests

Filtering

📄 Read: references/filtering.md

• Filter types: StartsWith, EndsWith, Contains via filterType
• Minimum character length with minLength (default: 0)
• Allow spaces in search with allowSpaces
• Limit visible suggestions with suggestionCount
• Case-sensitive filtering with ignoreCase
• Reducing filter calls with debounceDelay
• Custom server-side filtering with the filtering event

Templates

📄 Read: references/templates.md

• itemTemplate — customize each item in the suggestion popup
• displayTemplate — customize what is inserted into the editor upon selection
• noRecordsTemplate — custom message when no items match search
• spinnerTemplate — custom loading indicator for remote data

Customization

📄 Read: references/customization.md

• Show or hide mention character prefix with showMentionChar
• Change trigger character with mentionChar (default: @)
• Append suffix after selection with suffixText (space, newline)
• Control popup dimensions with popupHeight and popupWidth
• Leading space requirement with requireLeadingSpace
• Apply custom CSS styles with cssClass
• Highlight matched characters with highlight

Disabled Items

📄 Read: references/disabled-items.md

• Disable individual items via fields.disabled data source mapping
• Dynamically disable items at runtime using the disableItem method
• Disable multiple items by iterating

Sorting

📄 Read: references/sorting.md

• Sort suggestion list with sortOrder (None, Ascending, Descending)
• Ascending and descending sort examples

Accessibility

📄 Read: references/accessibility.md

• WCAG 2.2 (AA), Section 508, screen reader compliance
• WAI-ARIA attributes (aria-selected, aria-activedescendant, aria-owns)
• Full keyboard navigation (Arrow keys, Escape, Enter, Tab)
• Tips for accessible target element setup

API Reference

📄 Read: references/api.md

• Complete properties: allowSpaces, cssClass, dataSource, debounceDelay, displayTemplate, fields, filterType, highlight, htmlAttributes, ignoreCase, itemTemplate, locale, mentionChar, minLength, noRecordsTemplate, popupHeight, popupWidth, query, requireLeadingSpace, showMentionChar, sortOrder, spinnerTemplate, suffixText, suggestionCount, target
• MentionFieldSettings: text, value, groupBy, iconCss, disabled, htmlAttributes
• All events: actionBegin, actionComplete, actionFailure, beforeOpen, change, closed, created, destroyed, filtering, opened, select

Quick Start

Minimal Mention with string array:

@{
    var users = new string[] { "Adeline MacAdams", "Alba Torres", "Amy Fernandez", "Andrew Jack" };
}

<div id="mentionTarget" contenteditable="true"
     style="min-height: 100px; border: 1px solid #ccc; padding: 10px;">
    Type @ to mention someone
</div>

<ejs-mention id="mentionElement" target="#mentionTarget" dataSource="@users">
</ejs-mention>

Mention with object data and field mapping:

<div id="mentionTarget" contenteditable="true"
     style="min-height: 100px; border: 1px solid #ccc; padding: 10px;">
</div>

<ejs-mention id="mentionElement" target="#mentionTarget" dataSource="@ViewBag.data">
    <e-mention-fields text="Name" value="EmailId"></e-mention-fields>
</ejs-mention>

Controller:

public IActionResult Index()
{
    ViewBag.data = new List<EmailData>
    {
        new EmailData { Name = "Adeline MacAdams", EmailId = "adeline@example.com" },
        new EmailData { Name = "Alba Torres", EmailId = "alba@example.com" },
        new EmailData { Name = "Amy Fernandez", EmailId = "amy@example.com" }
    };
    return View();
}

public class EmailData
{
    public string Name { get; set; }
    public string EmailId { get; set; }
}

Common Patterns

Custom Trigger Character (# for tags)

<ejs-mention id="mentionElement" target="#mentionTarget"
    dataSource="@ViewBag.data"
    mentionChar="#"
    showMentionChar="true">
    <e-mention-fields text="TagName"></e-mention-fields>
</ejs-mention>

Mention with Suffix Space + No Leading Space Required

<ejs-mention id="mentionElement" target="#mentionTarget"
    dataSource="@ViewBag.data"
    suffixText=" "
    requireLeadingSpace="false">
    <e-mention-fields text="Name"></e-mention-fields>
</ejs-mention>

Remote Data with Filtering

<ejs-mention id="mentionElement" target="#mentionTarget"
    minLength="2"
    filterType="StartsWith"
    suggestionCount="10">
    <e-mention-fields text="ContactName" value="CustomerID"></e-mention-fields>
    <e-data-manager url="url"
        adaptor="ODataV4Adaptor" crossDomain="true">
    </e-data-manager>
</ejs-mention>

Custom Item Template

<ejs-mention id="mentionElement" target="#mentionTarget"
    dataSource="@ViewBag.data"
    itemTemplate="<span><img src='${EmpImage}' class='avatar'/><b>${FirstName}</b> - ${Department}</span>">
    <e-mention-fields text="FirstName" value="FirstName"></e-mention-fields>
</ejs-mention>

Handle Selection Event

<ejs-mention id="mentionElement" target="#mentionTarget"
    dataSource="@ViewBag.data"
    select="onMentionSelect">
    <e-mention-fields text="Name" value="EmailId"></e-mention-fields>
</ejs-mention>

<script>
    function onMentionSelect(args) {
        console.log("Mentioned user:", args.itemData.Name);
        console.log("Email:", args.itemData.EmailId);
    }
</script>

Key Properties Quick Reference

ComboBox

The ComboBox (<ejs-combobox>) is a textbox component that allows users to select or type a value from a predefined list. It combines the features of a textbox and dropdown, supporting custom values, filtering, grouping, templates, and accessibility.

Component Overview

Tag Helper: <ejs-combobox>
Namespace: Syncfusion.EJ2.DropDowns
NuGet: Syncfusion.EJ2.AspNet.Core

Key Features:

• User-defined custom values (allowCustom)
• Data binding from local arrays and remote sources
• Real-time filtering with search capability (allowFiltering, filterType)
• Grouping items using fields.groupBy
• Customizable templates: itemTemplate, headerTemplate, footerTemplate, groupTemplate, noRecordsTemplate
• Virtual scrolling for large datasets (enableVirtualization)
• Popup resize capability (allowResize)
• WCAG 2.2 accessibility compliance
• RTL rendering support
• Float label support (floatLabelType)

Documentation and Navigation Guide

Getting Started

📄 Read: references/combobox-getting-started.md

• NuGet package installation
• TagHelper registration in _ViewImports.cshtml
• Service registration in Program.cs
• Basic ComboBox implementation
• Custom value entry (allowCustom)
• Popup height and width configuration

Data Binding

📄 Read: references/combobox-data-binding.md

• Array of strings and array of objects
• Complex/nested object data binding
• Remote data with DataManager (OData, Web API, URL Adaptor)
• Field mapping (text, value, iconCss, groupBy, disabled)
• Pre-selected values

Filtering and Search

📄 Read: references/combobox-filtering-and-search.md

• Enable filtering with allowFiltering
• Filter types: StartsWith, EndsWith, Contains
• Minimum character threshold (minLength)
• Case-sensitive filtering with ignoreCase
• Diacritics filtering with ignoreAccent
• Debounce delay for performance
• No results handling

Grouping and Sorting

📄 Read: [references/combobox-grouping-and-sorting.md](refer

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