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github-actions[bot]KB Bot
andauthoredJan 28, 2025
Added new kb article how-to-append-percentage-and-namefield-radhtmlchart-pie-chart (#647)
Co-authored-by: KB Bot <kb-bot@telerik.com>
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---
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title: Appending Percentage and NameField to Pie Chart Items in RadHtmlChart for ASP.NET AJAX
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description: Learn how to append percentage values and name fields to each item in a RadHtmlChart Pie Chart dynamically using C# codebehind.
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type: how-to
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page_title: How to Dynamically Append Percentage and NameField to RadHtmlChart Pie Chart Items Using C#
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slug: how-to-append-percentage-and-namefield-radhtmlchart-pie-chart
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tags: radhtmlchart, asp.net ajax, pie chart, codebehind, c#, clienttemplate, data binding
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res_type: kb
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ticketid: 1677029
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---
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## Description
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When working with the [RadHtmlChart for ASP.NET AJAX](https://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/overview), you might want to dynamically append percentage values and name fields to each item in a Pie Chart directly from the codebehind using C#. This knowledge base article also answers the following questions:
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- How to use ClientTemplate in RadHtmlChart PieSeries with C#?
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- How to dynamically set colors for Pie Chart items in RadHtmlChart?
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- How to bind data to RadHtmlChart PieSeries using codebehind in ASP.NET AJAX?
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## Environment
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<table>
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<tbody>
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<tr>
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<td>Product</td>
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<td>RadHtmlChart for ASP.NET AJAX</td>
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</tr>
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</tbody>
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</table>
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## Solution
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To append percentage values and name fields to each item in a RadHtmlChart Pie Chart, and optionally set item colors dynamically from the codebehind, you can follow these steps:
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### Approach 1: Use a Dictionary for Color Mapping
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This approach allows you to map `DAYPART` values to their corresponding colors without modifying the database. A calculated `COLOR` column is added dynamically to the `DataTable`, which is then used to set the slice colors.
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**ASPX.CS:**
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```ASPX
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<telerik:RadHtmlChart runat="server" ID="DayPartsPieChart" Height="400px" Width="500px"
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Legend-Appearance-Position="Right"
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BorderColor="Black" BorderStyle="Solid" BorderWidth="2px"
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Transitions="true">
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<Appearance FillStyle-BackgroundColor="White"></Appearance>
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<PlotArea>
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<Series>
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<telerik:PieSeries>
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</telerik:PieSeries>
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</Series>
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</PlotArea>
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<Legend>
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<Appearance Visible="false" />
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</Legend>
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</telerik:RadHtmlChart>
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```
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```csharp
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protected void Page_Init(object sender, EventArgs e)
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{
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if (!IsPostBack)
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{
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LoadDayPartsPieChart();
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}
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}
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public void LoadDayPartsPieChart()
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{
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// Define and populate the data source
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DataTable table = new DataTable();
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table.Columns.Add("DAYPART", typeof(string));
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table.Columns.Add("PCT", typeof(decimal));
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table.Rows.Add("EM", 18.5m);
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table.Rows.Add("DT", 18.6m);
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table.Rows.Add("PT", 3.0m);
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table.Rows.Add("LN", 37.1m);
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table.Rows.Add("LE", 11.4m);
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table.Rows.Add("EF", 11.4m);
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// Define a dictionary for DAYPART-to-color mapping
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Dictionary<string, string> colorMapping = new Dictionary<string, string>
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{
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{ "EM", "Purple" },
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{ "DT", "Orange" },
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{ "PT", "Green" },
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{ "LN", "Blue" },
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{ "LE", "Red" },
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{ "EF", "Yellow" }
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};
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// Add a calculated COLOR column dynamically
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table.Columns.Add("COLOR", typeof(string));
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foreach (DataRow row in table.Rows)
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{
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string dayPart = row["DAYPART"].ToString();
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if (colorMapping.ContainsKey(dayPart))
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{
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row["COLOR"] = colorMapping[dayPart];
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}
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}
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// Clear existing series
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DayPartsPieChart.PlotArea.Series.Clear();
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// Create a new PieSeries
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Telerik.Web.UI.PieSeries pieSeries = new Telerik.Web.UI.PieSeries
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{
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DataFieldY = "PCT", // Bind PCT values to the pie slices
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NameField = "DAYPART", // Bind DAYPART names to labels
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ColorField = "COLOR", // Bind dynamically calculated COLOR field
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LabelsAppearance =
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{
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Position = Telerik.Web.UI.HtmlChart.PieAndDonutLabelsPosition.OutsideEnd,
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Visible = true,
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ClientTemplate = "#= dataItem.PCT # % \\n #= dataItem.DAYPART #"
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},
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TooltipsAppearance =
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{
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ClientTemplate = "#= dataItem.PCT # : \\n #= dataItem.DAYPART #"
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},
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VisibleInLegend = false
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};
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// Add the PieSeries to the chart
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DayPartsPieChart.PlotArea.Series.Add(pieSeries);
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// Bind the chart to the data source
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DayPartsPieChart.DataSource = table;
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DayPartsPieChart.DataBind();
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// Optionally update the chart title
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DayPartsPieChart.ChartTitle.Text = "Airings by Daypart";
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}
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```
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### Approach 2: Use the ColorField Property
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If your data source already includes a `COLOR` column, you can directly bind it to the `ColorField` property of the `PieSeries` to dynamically set the item colors.
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**ASPX.CS:**
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```csharp
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// Similar to Approach 1, but ensure your DataTable includes a COLOR column
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protected void Page_Init(object sender, EventArgs e)
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{
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if (!IsPostBack)
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{
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LoadDayPartsPieChart();
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}
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}
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public void LoadDayPartsPieChart()
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{
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// Define and populate the data source
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DataTable table = new DataTable();
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table.Columns.Add("DAYPART", typeof(string));
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table.Columns.Add("PCT", typeof(decimal));
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table.Columns.Add("COLOR", typeof(string)); // Add a COLOR column to the data source
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table.Rows.Add("EM", 18.5m, "Purple");
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table.Rows.Add("DT", 18.6m, "Orange");
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table.Rows.Add("PT", 3.0m, "Green");
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table.Rows.Add("LN", 37.1m, "Blue");
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table.Rows.Add("LE", 11.4m, "Red");
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table.Rows.Add("EF", 11.4m, "Yellow");
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// Clear existing series
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DayPartsPieChart.PlotArea.Series.Clear();
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// Create a new PieSeries
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Telerik.Web.UI.PieSeries pieSeries = new Telerik.Web.UI.PieSeries
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{
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DataFieldY = "PCT", // Bind PCT values to the pie slices
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NameField = "DAYPART", // Bind DAYPART names to labels
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ColorField = "COLOR", // Bind COLOR column to dynamically set colors
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LabelsAppearance =
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{
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Position = Telerik.Web.UI.HtmlChart.PieAndDonutLabelsPosition.OutsideEnd,
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Visible = true,
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ClientTemplate = "#= dataItem.PCT # % \\n #= dataItem.DAYPART #"
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},
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TooltipsAppearance =
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{
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ClientTemplate = "#= dataItem.PCT # : \\n #= dataItem.DAYPART #"
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},
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VisibleInLegend = false
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};
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// Add the PieSeries to the chart
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DayPartsPieChart.PlotArea.Series.Add(pieSeries);
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// Bind the chart to the data source
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DayPartsPieChart.DataSource = table;
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DayPartsPieChart.DataBind();
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// Optionally update the chart title
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DayPartsPieChart.ChartTitle.Text = "Airings by Daypart";
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}
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```
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Both approaches allow for dynamically appending percentage values and name fields to each Pie Chart item and setting their colors from the codebehind.
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## See Also
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- [RadHtmlChart Overview](https://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/overview)
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- [PieSeries - Telerik UI for ASP.NET AJAX](https://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/chart-types/pie-chart)
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- [RadHtmlChart ClientTemplate](https://www.telerik.com/products/aspnet-ajax/documentation/controls/htmlchart/functionality/clienttemplate/overview)

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