Implemented RadzenAsyncLoader component for Blazor, providing asynchronous data loading

Radzen.Blazor/RadzenAsyncLoader.razor

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+@typeparam TData
+
+@if (IsLoading && LoadingTemplate != null)
+{
+    @LoadingTemplate
+}
+else if (Result != null)
+{
+    @Template(Result)
+}

Radzen.Blazor/RadzenAsyncLoader.razor.cs

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+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Rendering;
+using System;
+using System.Threading.Tasks;
+
+namespace Radzen.Blazor
+{
+    /// <summary>
+    /// A generic component for asynchronously loading data and rendering templates based on the loading state.
+    /// </summary>
+    public partial class RadzenAsyncLoader<TData> : ComponentBase
+    {
+        /// <summary>
+        /// The template to render when data is loaded.
+        /// </summary>
+        [Parameter]
+        public RenderFragment<TData> Template { get; set; }
+
+        /// <summary>
+        /// The template to render while data is loading.
+        /// </summary>
+        [Parameter]
+        public RenderFragment LoadingTemplate { get; set; }
+
+        /// <summary>
+        /// The asynchronous task that fetches the data.
+        /// </summary>
+        [Parameter]
+        public Task<TData> DataTask { get; set; }
+
+        /// <summary>
+        /// A callback action invoked when an error occurs during data loading.
+        /// </summary>
+        [Parameter]
+        public Action<Exception> OnError { get; set; }
+
+        /// <summary>
+        /// Indicates whether the component is in a loading state.
+        /// </summary>
+        private bool IsLoading { get; set; } = true;
+
+        /// <summary>
+        /// The loaded data result.
+        /// </summary>
+        private TData Result { get; set; }
+
+        /// <summary>
+        /// Initializes the component and asynchronously loads data.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+        protected override async Task OnInitializedAsync()
+        {
+            try
+            {
+                Result = await DataTask;
+                IsLoading = false;
+            }
+            catch (Exception ex)
+            {
+                IsLoading = false;
+                if (OnError != null)
+                {
+                    OnError(ex);
+                }
+            }
+            finally
+            {
+                // Ensure UI updates after loading completes or encounters an error.
+                StateHasChanged();
+            }
+        }
+    }
+}

Radzen.DocFX/guides/components/asyncloader.md

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+# AsyncLoader component
+This article demonstrates how to use the AsyncLoader component.
+
+# Loading data asynchronously
+The AsyncLoader component enables loading data asynchronously in Blazor applications. It offers the flexibility to specify loading and loaded templates, handle errors during data retrieval, and update the UI accordingly.
+
+```
+<RadzenAsyncLoader TData="Server.Models.ApplicationUser" DataTask="@Security.GetUserById(context.Id)">
+    <LoadingTemplate>
+        <RadzenProgressBarCircular ProgressBarStyle="ProgressBarStyle.Primary" Value="100" ShowValue="false" Mode="ProgressBarMode.Indeterminate" Size="ProgressBarCircularSize.Small" />
+    </LoadingTemplate>
+    <Template Context="ctx">
+        <RadzenStack Orientation="Orientation.Horizontal" AlignItems="AlignItems.Center" Gap="0.5rem">
+            @foreach (var role in ctx.Roles)
+            {
+                <RadzenBadge Text="@role.Name" />
+            }
+        </RadzenStack>
+    </Template>
+</RadzenAsyncLoader>
+```