Show default message if Pie Chart on MVC 4 not build

Question

I am displaying a Pie chart on MVC 4. Its working fine when data is available.

But in case data is not found in a specific scenario, I want to show a default message like "Chart could not be generated".

Currently I am rendering Pie chart on a partial view.

Given below is my code.

Controller Action:

 public ActionResult PieChart(long dateValue, string regType)
        {
            List<PatchingFailurePieChart> lstRegType = BAL.GetFailureDetailsChart(CreatedOn, true, regType);

            if (lstRegType.Count > 0)
            {
                ArrayList xValue = new ArrayList();
                ArrayList yValue = new ArrayList();
                lstRegType.ToList().ForEach(rs => xValue.Add(rs.OSName));
                lstRegType.ToList().ForEach(rs => yValue.Add(rs.Count));

                new Chart(width: 750, height: 590, theme: ChartTheme.Blue)
                    .AddTitle("Pie chart as on date " + CreatedOn.ToString("MM/dd/yyyy"))
                    .AddLegend("OS Versions")
                    .AddSeries("Default", chartType: "Pie", xValue: xValue, yValues: yValue)
                    .Write("bmp");
            }
            ViewBag.dateValue = dateValue;
            ViewBag.regType = regType;
            return null;
        }

Partial View:

  <img  src="@Url.Action("PieChart", "PatchFailure", new { dateValue = @ViewBag.dateValue, regType = @ViewBag.regType })"/>

View: Which is calling Partial view

  @Html.Partial("PieChart");

Thanks in advance for any help.

Answer 1

I made it but it's not perfect. The data are read twice: when html page is opened and when chart is generated. Ideally would be to pass chart data to Url.Action call but probably it's not possible(?).

Use urls for testing: /ChartTest?dataExists=false /ChartTest?dataExists=true

Controller:

public class ChartTestController : Controller
    {
        /// <summary>
        /// Action method for main page.
        /// GET: /ChartTest/
        /// </summary>
        /// <param name="dataExists">It sets if chard should be displayed or "No data found text is displayed</param>
        /// <returns></returns>
        //
        public ActionResult Index(bool dataExists)
        {
            ChartViewModel model = null;

            if (dataExists)
            {
                model = new ChartViewModel
                {
                    Chart = GetChart()
                };
            }
            else
            {
                model = null;
            }

            return View(model);
        }

        /// <summary>
        /// it prepares Chart object
        /// </summary>
        /// <returns></returns>
        private Chart GetChart()
        {
            return new Chart(600, 400, ChartTheme.Blue)
                .AddTitle("Number of website readers")
                .AddLegend()
                .AddSeries(
                    name: "WebSite",
                    chartType: "Pie",
                    xValue: new[] { "Digg", "DZone", "DotNetKicks", "StumbleUpon" },
                    yValues: new[] { "150000", "180000", "120000", "250000" });

        }

        /* usage: 
        * http://localhost:54087/ChartTest/GetChart?dateValue=10&regType=aaa&dataExists=false
        * http://localhost:54087/ChartTest/GetChart?dateValue=10&regType=aaa&dataExists=true
        */
        public ActionResult GetChart(long dateValue, string regType)
        {            
            var result = GetChart();
            result.Write("jpg");
            return null;
        }
    }

Class ChartViewModel:

 public class ChartViewModel
    {
        public Chart Chart { get; set; }
    }

Index.cshtml:

@model codeFirstSample.Models.ChartViewModel
@{

    ViewBag.Title = "ChartTest";
}

<h2>ChartTest usage example</h2>


Chart :

@if (@Model == null)
{
    <p>No data found.</p>
}
else
{
    <img src="@Url.Action("GetChart", "ChartTest", new { dateValue = 1, regType = 2})" />

}