DxListBox<TData, TValue>.CustomData Property
Specifies an asynchronous function that loads List Box data based on the specified load options.
Namespace: DevExpress.Blazor
Assembly: DevExpress.Blazor.v24.1.dll
NuGet Package: DevExpress.Blazor
Declaration
[Parameter]
public Func<DataSourceLoadOptionsBase, CancellationToken, Task<LoadResult>> CustomData { get; set; }
Property Value
Type | Description |
---|---|
Func<DevExtreme.AspNet.Data.DataSourceLoadOptionsBase, CancellationToken, Task<DevExtreme.AspNet.Data.ResponseModel.LoadResult>> | A delegate that implements data load logic. |
Remarks
To bind the List Box to data that is stored on a remote service and is loaded through a Web API, assign the data type to the component’s T
parameter and use the CustomData
property to implement data load logic. This property specifies an asynchronous function that accepts two parameters:
- The DataSourceLoadOptionsBase object, which reflects the current List Box state.
- The CancellationToken object, which propagates a cancellation notification.
In this function, you can use the ConvertToGetRequestUri and ConvertToHttpContent extension methods to generate HTTP requests with parameters based on data load options. The function should return a Task<LoadResult> object.
Note that if you use the CustomData
property and virtual list render mode, the data item collection can include fake items for items that are still loading.
Implement a Controller
On a remote service, implement an API controller and create action methods that use the DevExtreme.AspNet.Data library’s DataSourceLoader class to create a LoadResult
object based on load options. If you pass a DataSourceLoadOptions class instance as an argument in controller actions, add a reference to the DevExtreme.AspNet.Mvc namespace from the DevExtreme.AspNet.Core NuGet package.
Example
@using CustomData.Data
@using DevExtreme.AspNet.Data
@using DevExtreme.AspNet.Data.ResponseModel
@using System.Threading
@using System.Threading.Tasks
@using System.Net.Http
@using System.Text.Json
<DxListBox TData="@(WebApiLookup)"
TValue="string"
CustomData="@LoadCustomData"
TextFieldName="Text" >
</DxListBox>
@code {
[Inject] protected HttpClient Client { get; set; }
protected Task<LoadResult> LoadCustomData(DataSourceLoadOptionsBase options, CancellationToken cancellationToken) {
return CustomDataHelper.LoadCustomData(Client, options, cancellationToken);
}
}