Data Binding in Combo Box Control

19 Feb 202422 minutes to read

The ComboBox loads the data either from local data sources or remote data services using the dataSource property. It supports the data type of array or DataManager.

The ComboBox also supports different kinds of data services such as OData, OData V4, and Web API, and data formats such as XML, JSON, and JSONP with the help of DataManager adaptors.

Fields	Type	Description
text	string	Specifies the display text of each list item.
value	number or string	Specifies the hidden data value mapped to each list item that should contain a unique value.
groupBy	string	Specifies the category under which the list item has to be grouped.
iconCss	string	Specifies the icon class of each list item.

NOTE

When binding complex data to the ComboBox, fields should be mapped correctly. Otherwise, the selected item remains undefined.

Binding local data

Local data can be represented in two ways as described below.

1. Array of simple data

The ComboBox has supported to load array of primitive data such as strings and numbers. Here, both value and text field act the same.

CSHTML

@Html.EJS().ComboBox("games").Placeholder("Select a game").PopupHeight("200px").DataSource((IEnumerable<object>)ViewBag.data).Render()

Arrayofstrings.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
        public ActionResult arrayofstring()
        {
            ViewBag.data = new string[] { "Badminton", "Basketball", "Cricket", "Football", "Golf", "Gymnastics", "Hockey", "Tennis" };
            return View();
        }
    }
}

2. Array of JSON data

The ComboBox can generate its list items through an array of complex data. For this, the appropriate columns should be mapped to the fields property.

In the following example, Vegetable column from complex data has been mapped to the value field.

CSHTML

@Html.EJS().ComboBox("Vegetables").Placeholder("Select a Vegetables").PopupHeight("200px").DataSource((IEnumerable<object>)ViewBag.data).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings { Value = "Vegetable" }).Render()

Arrayofobjects.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
        public ActionResult arrayofobjects()
        {
            ViewBag.data = new Vegetables().VegetablesList();
            return View();
        }
    }
}

3. Array of Complex data

The ComboBox can generate its list items through an array of complex data. For this, the appropriate columns should be mapped to the fields property.

In the following example, Code.Id column and Country.CountryId column from complex data have been mapped to the value field and text field, respectively.

CSHTML

@Html.EJS().ComboBox("games").Placeholder("Select a game").PopupHeight("200px").DataSource((IEnumerable<Object>)ViewBag.data).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings { Text = "Country.CountryId", Value = "Code.Id" }).Render()

Complexdata.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxControleler : Controller
    {
        public ActionResult complexdata()
        {
            ViewBag.data = new Complex().GetData();
            return View();
        }
    }
}

Binding remote data

The ComboBox supports retrieval of data from remote data services with the help of DataManager component. The Query property is used to fetch data from the database and bind it to the ComboBox.

In the following sample, displayed first 6 contacts from the customer table of Northwind Data Service.

CSHTML

@Html.EJS().ComboBox("customers").Placeholder("Select a customer").PopupHeight("200px").DataSource(dataManger =>
            dataManger.Url("https://services.odata.org/V4/Northwind/Northwind.svc/").Adaptor("ODataV4Adaptor").CrossDomain(true)).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings
            {
                Text = "ContactName",
                Value = "CustomerID"
            }).Query("new ej.data.Query().from('Customers').select(['ContactName', 'CustomerID']).take(6)").Render()

Remotedata.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
        public ActionResult remotedata()
        {
            return View();
        }
    }
}

NOTE

View Sample in GitHub.

Bind to URL Adaptor

The ComboBox supports retrieval of data from URL adaptor.

CSHTML

@Html.EJS().ComboBox("games").Placeholder("Select a Country").PopupHeight("200px").DataSource(dataManger =>
    dataManger.Url("/ComboBox/UrlDatasource").Adaptor("UrlAdaptor").CrossDomain(true)).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings
    {
        Value = "ShipCountry"
    }).Render()

Urldata.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
       public ActionResult Index()
        {
            return View();
        }
        public ActionResult UrlDatasource([FromBody]Data dm)
        {
            var val = OrdersDetails.GetAllRecords();
            var Data = val.ToList();
            var count = val.Count();
            if (dm.where != null)
            {
                Data = (from cust in Data
                        where cust.ShipCountry.ToLower().StartsWith(dm.@where[0].value.ToString())
                        select cust).ToList();
            }
            if (dm.take != 0)
                Data = Data.Take(dm.take).ToList();
            return Json(Data);
        }


        public class Data
        {
            public int take { get; set; }
            public List<Wheres> where { get; set; }
        }

        public class Wheres
        {
            public string field { get; set; }
            public bool ignoreAccent { get; set; }

            public bool ignoreCase { get; set; }

            public bool isComplex { get; set; }

            public string value { get; set; }
            public string Operator { get; set; }

        }
        public class OrdersDetails
        {
            public static List<OrdersDetails> order = new List<OrdersDetails>();
            public OrdersDetails()
            {

            }
            public OrdersDetails(int OrderID, string CustomerId, int EmployeeId, double Freight, bool Verified, DateTime OrderDate, string ShipCity, string ShipName, string ShipCountry, DateTime ShippedDate, string ShipAddress)
            {
                this.OrderID = OrderID;
                this.CustomerID = CustomerId;
                this.EmployeeID = EmployeeId;
                this.Freight = Freight;
                this.ShipCity = ShipCity;
                this.Verified = Verified;
                this.OrderDate = OrderDate;
                this.ShipName = ShipName;
                this.ShipCountry = ShipCountry;
                this.ShippedDate = ShippedDate;
                this.ShipAddress = ShipAddress;
            }
            public static List<OrdersDetails> GetAllRecords()
            {
                if (order.Count() == 0)
                {
                    int code = 10000;
                    for (int i = 1; i < 10; i++)
                    {
                        order.Add(new OrdersDetails(code + 1, "ALFKI", i + 0, 2.3 * i, false, new DateTime(1991, 05, 15), "Berlin", "Simons bistro", "Denmark", new DateTime(1996, 7, 16), "Kirchgasse 6"));
                        order.Add(new OrdersDetails(code + 2, "ANATR", i + 2, 3.3 * i, true, new DateTime(1990, 04, 04), "Madrid", "Queen Cozinha", "Brazil", new DateTime(1996, 9, 11), "Avda. Azteca 123"));
                        order.Add(new OrdersDetails(code + 3, "ANTON", i + 1, 4.3 * i, true, new DateTime(1957, 11, 30), "Cholchester", "Frankenversand", "Germany", new DateTime(1996, 10, 7), "Carrera 52 con Ave. Bolívar #65-98 Llano Largo"));
                        order.Add(new OrdersDetails(code + 4, "BLONP", i + 3, 5.3 * i, false, new DateTime(1930, 10, 22), "Marseille", "Ernst Handel", "Austria", new DateTime(1996, 12, 30), "Magazinweg 7"));
                        order.Add(new OrdersDetails(code + 5, "BOLID", i + 4, 6.3 * i, true, new DateTime(1953, 02, 18), "Tsawassen", "Hanari Carnes", "Switzerland", new DateTime(1997, 12, 3), "1029 - 12th Ave. S."));
                        code += 5;
                    }
                }
                return order;
            }

            public int? OrderID { get; set; }
            public string CustomerID { get; set; }
            public int? EmployeeID { get; set; }
            public double? Freight { get; set; }
            public string ShipCity { get; set; }
            public bool Verified { get; set; }
            public DateTime OrderDate { get; set; }

            public string ShipName { get; set; }

            public string ShipCountry { get; set; }

            public DateTime ShippedDate { get; set; }
            public string ShipAddress { get; set; }
        }
    }
}

Web API Adaptor

Use the WebApiAdaptor to bind ComboBox with Web API created using OData.

CSHTML

<div id='web-data' class='col-lg-6' style='padding-top:15px'>
    <div class='content'>
        @Html.EJS().ComboBox("games").DataSource(dataManger =>
            dataManger.Url("/api/ComboBox/").Adaptor("WebApiAdaptor")).Render()
    </div>
</div>

Webapi.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    public class ComboBoxController : Controller
    {
        List<string> game = new List<string>();
        [HttpGet]
        public List<string> Get()
        {
            game.Add("Badminton");
            game.Add("Basketball");
            game.Add("Cricket");
            game.Add("Golf");
            game.Add("Gymnastics");
            game.Add("Tennis");
            game.Add("Hockey");
            return game;
        }
    }
}

Binding with OData services

OData is a standardized protocol for creating and consuming data. You can retrieve data from OData service using the DataManager.

CSHTML

<div id='o-data' class='col-lg-6' style='padding-top:15px'>
    <div class='content'>
        @Html.EJS().ComboBox("customers").Placeholder("Select a customer").PopupHeight("200px").DataSource(dataManger =>
            dataManger.Url("https://js.syncfusion.com/ejServices/Wcf/Northwind.svc/Orders/").Adaptor("ODataAdaptor").CrossDomain(true)).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings
            {
                Value = "CustomerID"
            }).Query("new ej.data.Query().select(['CustomerID']).take(7)").Render()
    </div>
</div>

Odata.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
        public ActionResult odata()
        {
            return View();
        }
    }
}

Offline mode

To avoid post back for every action, set the ComboBox to load all data on initialization and make the actions process in client-side. To enable this behavior, use the Offline property of DataManager.

CSHTML

<div id='o-data' class='col-lg-6' style='padding-top:15px'>
    <div class='content'>
        @Html.EJS().ComboBox("customers").Placeholder("Select a customer").PopupHeight("200px").DataSource(dataManger =>
            dataManger.Url("http://js.syncfusion.com/ejServices/Wcf/Northwind.svc/Orders/").Offline(true).Adaptor("ODataAdaptor").CrossDomain(true)).Fields(new Syncfusion.EJ2.DropDowns.ComboBoxFieldSettings
            {
                Value = "CustomerID"
            }).Query("new ej.data.Query().select(['CustomerID']).take(7)").Render()
    </div>
</div>

Offline.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using WebApplication1.Models;

namespace WebApplication1.Controllers
{
    public class ComboBoxController : Controller
    {
        public IActionResult offline()
        {
            return View();
        }
    }
}

See also

• How to acheive cascading
• How to load data using template
• How to group the data using header
• How to filter the bound data