blazor-docs/knowledge-base/drawer-chart-refresh.md

title	description	type	page_title	slug	position	tags	ticketid	res_type
Refresh a Chart Inside a Drawer	How to refresh a Chart within a Drawer content.	how-to	Refresh a Chart Inside a Drawer	drawer-kb-chart-refresh			1583102	kb

Environment

Product

Drawer for Blazor, Charts for Blazor

Description

This knowledge base article answers the following questions:

• How do I refresh a Chart inside a Drawer?
• Is it possible to refresh a Chart when the Drawer is expanded?

Solution

1. To indicate when the Chart requires a refresh, create a bool flag and set it within the Drawer's [ExpandedChanged]({%slug drawer-events%}#expandedchanged) handler.
2. Call the Chart's [Refresh() method]({%slug components/chart/overview%}#chart-reference-and-methods) within the OnAfterRenderAsync lifecycle method. Set a brief delay to allow the Drawer to finish expanding before the refresh.

<TelerikButton OnClick="@(() => DrawerRef.ToggleAsync())" Icon="@SvgIcon.Menu">Toggle Drawer</TelerikButton>

<TelerikDrawer Expanded="@Expanded"
               ExpandedChanged="@ExpandedChanged"
               Data="@Data"
               Mode="@DrawerMode.Push"
               @ref="@DrawerRef">
    <DrawerContent>
        <TelerikChart @ref="@ChartRef">
            <ChartSeriesItems>
                <ChartSeries Type="@ChartSeriesType.Heatmap"
                             Name="Commits Made per developer"
                             Data="@HeatmapData"
                             XField="@(nameof(MyHeatmapDataModel.Week))"
                             YField="@(nameof(MyHeatmapDataModel.Day))"
                             Field="@(nameof(MyHeatmapDataModel.CommitsNumber))">

                </ChartSeries>
            </ChartSeriesItems>
        </TelerikChart>
    </DrawerContent>
</TelerikDrawer>

@code {
    private TelerikDrawer<DrawerItem> DrawerRef { get; set; }
    private TelerikChart ChartRef { get; set; }

    private bool Expanded { get; set; }
    private bool ShouldRefreshChart { get; set; }

    private async Task ExpandedChanged(bool newExpanded)
    {
        Expanded = newExpanded;

        ShouldRefreshChart = true;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (ShouldRefreshChart)
        {
            ShouldRefreshChart = false;
            await Task.Delay(500);
            ChartRef.Refresh();
        }

        await base.OnAfterRenderAsync(firstRender);
    }

    protected override void OnInitialized()
    {
        HeatmapData = GetMyHeatmapData();
    }

    #region Drawer Data
    private IEnumerable<DrawerItem> Data { get; set; } =
        new List<DrawerItem>
            {
            new DrawerItem { Text = "Page", Icon = SvgIcon.Plus}
            };

    public class DrawerItem
    {
        public string Text { get; set; }
        public ISvgIcon Icon { get; set; }
    }
    #endregion

    #region Chart Data
    private List<MyHeatmapDataModel> HeatmapData { get; set; }

    private List<MyHeatmapDataModel> GetMyHeatmapData()
    {
        List<MyHeatmapDataModel> data = new List<MyHeatmapDataModel>()
        {
            new MyHeatmapDataModel("John", 14, 1, "Mon"),
            new MyHeatmapDataModel("Idell", 8, 2, "Mon"),
            new MyHeatmapDataModel("Ines", 13, 3, "Mon"),
            new MyHeatmapDataModel("Stephen", 22, 4, "Mon"),
            new MyHeatmapDataModel("John", 7, 1, "Tue"),
            new MyHeatmapDataModel("Idell", 18, 2, "Tue"),
            new MyHeatmapDataModel("Ines", 2, 3, "Tue"),
            new MyHeatmapDataModel("Stephen", 5, 4, "Tue"),
            new MyHeatmapDataModel("John", 10, 1, "Wed"),
            new MyHeatmapDataModel("Idell", 11, 2, "Wed"),
            new MyHeatmapDataModel("Ines", 20, 3, "Wed"),
            new MyHeatmapDataModel("Stephen", 15, 4, "Wed")
        };

        return data;
    }

    private class MyHeatmapDataModel
    {
        public MyHeatmapDataModel() { }

        public MyHeatmapDataModel(string devName, int commits, int week, string day)
        {
            DeveloperName = devName;
            CommitsNumber = commits;
            Week = week;
            Day = day;
        }

        public string DeveloperName { get; set; }
        public int CommitsNumber { get; set; }
        public int Week { get; set; }
        public string Day { get; set; }
    }
    #endregion
}

See Also

• [Drawer Events]({%slug drawer-events%})
• [Charts Overview]({%slug components/chart/overview%})
• [Prevent Drawer from collapsing on item click]({%slug drawer-kb-prevent-collapse%})