DataAsyncProperty.CancellationToken.razor

@page "/DataAsyncUsingCancellationToken"
@inject WeatherForecastService WeatherForecastService

<h2>DataAsync: Cancellation Token</h2>

<p>
    This example uses the <a class="helplink" href="https://docs.devexpress.com/Blazor/DevExpress.Blazor.DxDataGrid-1.DataAsync" target="_blank">DataAsync</a> property to bind the Data Grid to a strongly typed collection that is loaded asynchronously. The <b>DataAsync</b> delegate accepts a cancellation token as a parameter. In this example, the token receives a cancellation signal when the <b>Data Grid</b> tab is closed. When you switch between tabs before grid data is loaded, the cancelled task count is increased.
</p>


<p>
    Note that the <b>Render GUID</b> does not change during page initialization. This means the page is rendered only once.
</p>

<p>
    <b>Render GUID</b>: @Guid.NewGuid()
</p>

<DxTabs>
    <DxTabPage Text="Data Grid">
        <DxDataGrid DataAsync="@LoadDataAsync" KeyFieldName="Id">
            <Columns>
                <DxDataGridColumn Field="@nameof(WeatherForecast.Summary)" />
                <DxDataGridDateEditColumn Field="@nameof(WeatherForecast.Date)" />
                <DxDataGridSpinEditColumn Field="@nameof(WeatherForecast.TemperatureC)" />
                <DxDataGridSpinEditColumn Field="@nameof(WeatherForecast.TemperatureF)" />
            </Columns>
        </DxDataGrid>
    </DxTabPage>
    <DxTabPage Text="Cancelled Task Counter">
        Cancelled Task Count: @CancelledTaskCount
    </DxTabPage>
</DxTabs>
@code {
    int CancelledTaskCount = 0;
    async Task<IEnumerable<WeatherForecast>> LoadDataAsync(CancellationToken token) {
        try {
            return await WeatherForecastService.GetForecastAsync(DateTime.Now.Date, token);
        } catch (TaskCanceledException) {
            CancelledTaskCount++;
        }
        return Enumerable.Empty<WeatherForecast>();
    }
}