kb(drawer): refresh a chart inside a drawer

knowledge-base/drawer-chart-refresh.md

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+---
+title: Refresh a Chart Inside a Drawer
+description: How to refresh a Chart within a Drawer content.
+type: how-to
+page_title: Refresh a Chart Inside a Drawer
+slug: drawer-kb-chart-refresh
+position: 
+tags: 
+ticketid: 1583102
+res_type: kb
+---
+
+## Environment
+<table>
+	<tbody>
+		<tr>
+			<td>Product</td>
+			<td>Drawer for Blazor,<br /> Charts for Blazor</td>
+		</tr>
+	</tbody>
+</table>
+
+## 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. Create a bool flag and set it within the Drawer's [`ExpandedChanged`]({%slug drawer-events%}#expandedchanged) handler to indicate when the Chart needs to be refreshed
+2. Call the Chart's [`Refresh()` method]({%slug components/chart/overview%}#chart-reference-and-methods) within the `OnAfterRenderAsync` lifecycle method after a brief delay that allows the Drawer to finish expanding
+
+````CSHTML
+<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
+}
+````