Data Binding in Blazor MultiColumn ComboBox Component
22 Jan 202521 minutes to read
The MultiColumn ComboBox can retrieve data from either local data sources or remote data services. To connect local data, use the DataSource property. For remote data binding, utilize the DataManager.
- TItem - Specifies the type of the datasource of the MultiColumn ComboBox component.
Binding local data
The MultiColumn ComboBox loads the data from local data sources through the DataSource property. It supports the data type of Array of primitive type, Array of object, List of primitive type,List of object, Observable Collection, ExpandoObject, DynamicObject.
@using Syncfusion.Blazor.MultiColumnComboBox
<SfMultiColumnComboBox @bind-Value="@Value" DataSource="@Products" PopupWidth="600px" ValueField="Name" TextField="Name" Placeholder="Select any product"></SfMultiColumnComboBox>
@code {
public class Product
{
public string Name { get; set; }
public decimal Price { get; set; }
public string Availability { get; set; }
public string Category { get; set; }
public double Rating { get; set; }
}
private List<Product> Products = new List<Product>();
private string Value { get; set; } = "Smartphone";
protected override Task OnInitializedAsync()
{
Products = new List<Product>
{
new Product { Name = "Laptop", Price = 999.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.5 },
new Product { Name = "Smartphone", Price = 599.99m, Availability = "Out of Stock", Category = "Electronics", Rating = 4.3 },
new Product { Name = "Tablet", Price = 299.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.2 },
new Product { Name = "Headphones", Price = 49.99m, Availability = "In Stock", Category = "Accessories", Rating = 4.0 },
new Product { Name = "Smartwatch", Price = 199.99m, Availability = "Limited Stock", Category = "Wearables", Rating = 4.4 },
new Product { Name = "Monitor", Price = 129.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.6 },
};
return base.OnInitializedAsync();
}
}
Index value binding
Index value binding can be accomplished with the bind-Index attribute, which supports both integer and nullable integer types. This attribute allows you to bind values according to their corresponding index.
@using Syncfusion.Blazor.MultiColumnComboBox
<SfMultiColumnComboBox TItem="Product" TValue="string" @bind-Index="@ComboIndex" DataSource="@Products" PopupWidth="600px" ValueField="Name" TextField="Name" Placeholder="Select any product"></SfMultiColumnComboBox>
@code {
public class Product
{
public string Name { get; set; }
public decimal Price { get; set; }
public string Availability { get; set; }
public string Category { get; set; }
public double Rating { get; set; }
}
private List<Product> Products = new List<Product>();
private int? ComboIndex { get; set; } = 2;
protected override Task OnInitializedAsync()
{
Products = new List<Product>
{
new Product { Name = "Laptop", Price = 999.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.5 },
new Product { Name = "Smartphone", Price = 599.99m, Availability = "Out of Stock", Category = "Electronics", Rating = 4.3 },
new Product { Name = "Tablet", Price = 299.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.2 },
new Product { Name = "Headphones", Price = 49.99m, Availability = "In Stock", Category = "Accessories", Rating = 4.0 },
new Product { Name = "Smartwatch", Price = 199.99m, Availability = "Limited Stock", Category = "Wearables", Rating = 4.4 },
new Product { Name = "Monitor", Price = 129.99m, Availability = "In Stock", Category = "Electronics", Rating = 4.6 },
new Product { Name = "Keyboard", Price = 39.99m, Availability = "In Stock", Category = "Accessories", Rating = 4.1 },
new Product { Name = "Mouse", Price = 19.99m, Availability = "Out of Stock", Category = "Accessories", Rating = 4.3 },
};
return base.OnInitializedAsync();
}
}Expando object binding
Bind the ExpandoObject data to the MultiColumn ComboBox component. In the following example, the ExpandoObject is bound to the collection of vehicles data.
@using Syncfusion.Blazor.MultiColumnComboBox
@using System.Dynamic
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="ExpandoObject" TValue="string" @bind-Value="@VehicleValue" DataSource="VehicleData" AllowFiltering=true ValueField="ID" TextField="Text" PopupWidth="600px" Placeholder="e.g. Andrew">
</SfMultiColumnComboBox>
@code {
public string VehicleValue { get; set; } = "1011";
public List<ExpandoObject> VehicleData { get; set; } = new List<ExpandoObject>();
protected override void OnInitialized()
{
VehicleData = Enumerable.Range(1, 15).Select((x) =>
{
dynamic d = new ExpandoObject();
d.ID = (1000 + x).ToString();
d.Text = (new string[] { "Hennessey Venom", "Bugatti Chiron", "Bugatti Veyron Super Sport", "SSC Ultimate Aero", "Koenigsegg CCR", "McLaren F1", "Aston Martin One- 77", "Jaguar XJ220", "McLaren P1", "Ferrari LaFerrari", "Mahindra Jaguar", "Hyundai Toyota", "Jeep Volkswagen", "Tata Maruti Suzuki", "Audi Mercedes Benz" }[x - 1]);
return d;
}).Cast<ExpandoObject>().ToList<ExpandoObject>();
}
}
Dynamic object binding
Bind the DynamicObject data to the MultiColumn ComboBox component. In the following example, the DynamicObject is bound to the collection of customer data.
@using Syncfusion.Blazor.MultiColumnComboBox
@using System.Dynamic
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="DynamicDictionary" TValue="string" @bind-Value="@NameValue" DataSource="Orders" AllowFiltering=true ValueField="CustomerName" TextField="CustomerName" PopupWidth="600px" Placeholder="e.g. Andrew">
</SfMultiColumnComboBox>
@code {
public string NameValue { get; set; } = "Margaret";
public List<DynamicDictionary> Orders = new List<DynamicDictionary>() { };
protected override void OnInitialized()
{
Orders = Enumerable.Range(1, 15).Select((x) =>
{
dynamic d = new DynamicDictionary();
d.OrderID = 1000 + x;
d.CustomerName = (new string[] { "Nancy", "Andrew", "Janet", "Margaret", "Steven", "Michael", "Robert", "Anne", "Nige", "Fuller", "Dodsworth", "Leverling", "Callahan", "Suyama", "Davolio" }[x - 1]);
return d;
}).Cast<DynamicDictionary>().ToList<DynamicDictionary>();
}
public class DynamicDictionary : System.Dynamic.DynamicObject
{
Dictionary<string, object> dictionary = new Dictionary<string, object>();
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
string name = binder.Name;
return dictionary.TryGetValue(name, out result);
}
public override bool TrySetMember(SetMemberBinder binder, object value)
{
dictionary[binder.Name] = value;
return true;
}
//The GetDynamicMemberNames method of DynamicObject class must be overridden and return the property names to perform data operation and editing while using DynamicObject.
public override System.Collections.Generic.IEnumerable<string> GetDynamicMemberNames()
{
return this.dictionary?.Keys;
}
}
}
ValueTuple data binding
Bind the ValueTuple data to the MultiColumn ComboBox component. The following code helps you to get a string value from the enumeration data by using ValueTuple
@using Syncfusion.Blazor.DropDowns;
<SfComboBox TItem="(DayOfWeek, string)" Width="250px" TValue="DayOfWeek"
DataSource="@(Enum.GetValues<DayOfWeek>().Select(e => (e, e.ToString())))">
<ComboBoxFieldSettings Value="Item1" Text="Item2" />
</SfComboBox>Binding remote data
The MultiColumn ComboBox loads the data from remote data services through the DataSource property.
The MultiColumn ComboBox supports the retrieval of data from the remote data services with the help of the DataManager control. The Query property is used to fetch data from the database and bind it to the MultiColumn ComboBox.
- DataManager.Url - Defines the service endpoint to fetch data.
- DataManager.Adaptor - Defines the adaptor option. By default, the ODataAdaptor is used for remote binding. The adaptor is responsible for processing responses and requests from or to the service endpoint.
- Syncfusion.Blazor.Data package provides some predefined adaptors that are designed to interact with particular service endpoints.
OnActionBegin event
The OnActionBegin event triggers before fetching data from the remote server.
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="EmployeeData" TValue="string" AllowFiltering=true ValueField="EmployeeID" OnActionBegin="@OnActionBeginhandler" TextField="FirstName" PopupWidth="600px" Placeholder="e.g. Andrew">
<SfDataManager Url="https://blazor.syncfusion.com/services/release/api/Employees" CrossDomain="true" Adaptor="Syncfusion.Blazor.Adaptors.WebApiAdaptor"></SfDataManager>
</SfMultiColumnComboBox>
@code {
public Query RemoteQuery = new Query();
public class EmployeeData
{
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Country { get; set; }
}
private void OnActionBeginhandler(ActionBeginEventArgs args)
{
// Here, you can customize your code.
}
}OnActionFailure event
The OnActionFailure event triggers when the data fetch request from the remote server fails.
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="EmployeeData" TValue="string" AllowFiltering=true ValueField="EmployeeID" OnActionFailure="@OnActionFailurehandler" TextField="FirstName" PopupWidth="600px" Placeholder="e.g. Andrew">
<SfDataManager Url="https://blazor.syncfusion.com/services/release/api/Employees" CrossDomain="true" Adaptor="Syncfusion.Blazor.Adaptors.WebApiAdaptor"></SfDataManager>
</SfMultiColumnComboBox>
@code {
public Query RemoteQuery = new Query();
public class EmployeeData
{
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Country { get; set; }
}
private void OnActionFailurehandler(Exception args)
{
// Here, you can customize your code.
}
}OData v4 services
The OData v4 Adaptor provides the ability to consume and manipulate data from OData v4 services. The following sample displays the first six customer details from Customers table of the Northwind Data Service.
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="OrderDetails" TValue="string" AllowFiltering=true ValueField="CustomerID" TextField="CustomerID" PopupWidth="600px" Placeholder="e.g. Andrew">
<SfDataManager Url="https://services.odata.org/V4/Northwind/Northwind.svc/Orders" Adaptor="Syncfusion.Blazor.Adaptors.ODataV4Adaptor" CrossDomain=true></SfDataManager>
</SfMultiColumnComboBox>
@code {
public string OrderValue { get; set; } = "TOMSP";
public Query Query = new Query().Select(new List<string> { "CustomerID", "OrderID" }).Take(6).RequiresCount();
public class OrderDetails
{
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
The Web API Adaptor is used to interact with Web API created under OData standards. The WebApiAdaptor is extended from the ODataAdaptor. Hence to use the WebApiAdaptor, the endpoint should understand the OData formatted queries sent along with the request.
@using Syncfusion.Blazor.Data
@using Syncfusion.Blazor.DropDowns
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="EmployeeData" TValue="string" AllowFiltering=true ValueField="EmployeeID" OnActionBegin="@OnActionBeginhandler" TextField="FirstName" PopupWidth="600px" Placeholder="e.g. Andrew">
<SfDataManager Url="https://blazor.syncfusion.com/services/release/api/Employees" CrossDomain="true" Adaptor="Syncfusion.Blazor.Adaptors.WebApiAdaptor"></SfDataManager>
</SfMultiColumnComboBox>
@code {
public Query RemoteQuery = new Query();
public class EmployeeData
{
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Country { get; set; }
}
private void OnActionBeginhandler(ActionBeginEventArgs args)
{
// Here, you can customize your code.
}
}
Offline mode
To avoid post back for every action, set the MultiColumn ComboBox to load all data on initialization and make the actions process on the client-side. To enable this behavior, use the Offline property of DataManager.
The following example is for remote data binding and enabled offline mode.
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="EmployeeData" TValue="string" AllowFiltering=true ValueField="EmployeeID" OnActionBegin="@OnActionBeginhandler" TextField="FirstName" PopupWidth="600px" Placeholder="e.g. Andrew">
<SfDataManager Url="https://blazor.syncfusion.com/services/release/api/Employees" Offline="true" CrossDomain="true" Adaptor="Syncfusion.Blazor.Adaptors.WebApiAdaptor"></SfDataManager>
</SfMultiColumnComboBox>
@code {
public Query RemoteQuery = new Query();
public class EmployeeData
{
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Country { get; set; }
}
private void OnActionBeginhandler(ActionBeginEventArgs args)
{
// Here, you can customize your code.
}
}Entity Framework
Follow these steps to consume data from the Entity Framework in the MultiColumn ComboBox component.
Create DBContext class
The first step is to create a DBContext class called OrderContext to connect to a Microsoft SQL Server database.
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using EFDropDown.Shared.Models;
namespace EFDropDown.Shared.DataAccess
{
public class OrderContext : DbContext
{
public virtual DbSet<Shared.Models.Order> Orders { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
if (!optionsBuilder.IsConfigured)
{
optionsBuilder.UseSqlServer(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\Blazor\DropDownList\EFDropDown\Shared\App_Data\NORTHWND.MDF;Integrated Security=True;Connect Timeout=30");
}
}
}
}Create data access layer to perform data operation
Now, create a class named OrderDataAccessLayer, which act as data access layer for retrieving the records from the database table.
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using EFDropDown.Shared.Models;
namespace EFDropDown.Shared.DataAccess
{
public class OrderDataAccessLayer
{
OrderContext db = new OrderContext();
//To Get all Orders details
public DbSet<Order> GetAllOrders()
{
try
{
return db.Orders;
}
catch
{
throw;
}
}
}
}Creating web API controller
A Web API Controller has to be created, which allows the MultiColumn ComboBox to directly consume data from the Entity Framework.
using EFDropDown.Shared.DataAccess;
using EFDropDown.Shared.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Primitives;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using Microsoft.AspNetCore.Http;
namespace EFDropDown.Controllers
{
[Route("api/[controller]")]
[ApiController]
//TreeGrid
public class DefaultController : ControllerBase
{
OrderDataAccessLayer db = new OrderDataAccessLayer();
[HttpGet]
public object Get()
{
IQueryable<Order> data = db.GetAllOrders().AsQueryable();
var count = data.Count();
var queryString = Request.Query;
if (queryString.Keys.Contains("$inlinecount"))
{
StringValues Skip;
StringValues Take;
int skip = (queryString.TryGetValue("$skip", out Skip)) ? Convert.ToInt32(Skip[0]) : 0;
int top = (queryString.TryGetValue("$top", out Take)) ? Convert.ToInt32(Take[0]) : data.Count();
return new { Items = data.Skip(skip).Take(top), Count = count };
}
else
{
return data;
}
}
}
}Configure MultiColumn ComboBox component using Web API adaptor
Now, configure the MultiColumn ComboBox using the SfDataManager to interact with the created Web API and consume the data appropriately. To interact with web API, use the WebApiAdaptor.
@using Syncfusion.Blazor.MultiColumnComboBox
@using Syncfusion.Blazor
@using Syncfusion.Blazor.Data
<SfMultiColumnComboBox TItem="Order" TValue="string" AllowFiltering=true ValueField="ShipCountry" TextField="ShipCountry" PopupWidth="1000px" Placeholder="e.g. Andrew">
<SfDataManager Url="api/Default" Adaptor="Adaptors.WebApiAdaptor" CrossDomain="true"></SfDataManager>
</SfMultiColumnComboBox>
@code {
public class Order
{
public int? OrderID { get; set; }
public string ShipCountry { get; set; }
}
}