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Pie Chart Databinding

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answered on 26 Sep 2008, 04:41 PM

Thanks Ves.

I was able to get it to work, but unfortunately not in quite the same manner as your example. When binding to a list of objects, e.DataItem is a DataRowView, so I can't cast it to my object type. Not sure why (since I'm not binding to a DataTable), but the code you posted threw an exception for that reason.

I was able to get it to work via the following, but this is kinda messy.

protected void RadChart1_ItemDataBound(object sender, ChartItemDataBoundEventArgs e)
{
        DataRowView drv = (DataRowView)e.DataItem;
        e.SeriesItem.Name = drv.Row["Name"].ToString();
}

What I'd really like to do is achieve the same effect by settting one property on the chart prior to calling DataBind(). Roughly, something like this:

protected override void PrepareChart()
{
        RadChart1.DataSource = MyApiCall();
        RadChart1.LegendLabelField = "Name";
        RadChart1.DataBind();
}

Ross

answered on 02 Oct 2008, 01:33 PM

I have to thank both Ross and Telerik for this posting. I just ran across the same issue and was able to do it in seconds with Ross' followup.

For Telerik - I'd second the request for the ability to set properties as suggested.

I would also like to add a request or more information on how I could append or swap the text from the series.item.name with the DefaultLabelValue?

What I would like to do is to not display the legend, but rather have the name of the series item display by the pie chart in addition to the percentage. Example:

Right now it's showing 53% and 47%, but the legend shows Not Seen 53% and Seen 47%. How do I go about having this combined and shown on the chart rather than in the legend? If I change defaultlabelvalue to #ITEM it shows Item 1 and Item 2, not very useful to the user.

answered on 27 Aug 2010, 07:43 PM

[edit: I figured out the solution, see my post below this one]

I am also facing this issue, and it seems silly to me that so much work has to go into getting the Labels to be displayed instead of "Item 0", "item 1"... perhaps I'm missing something. The pie chart legend obviously knows which colors map to with item, so why wouldn't it also know the label for that item.

I have tried many combinations of setting LegendDisplayMode, SmartLabelsEnabled and UseAutoGeneratedItems. I really don't want to have to write a separate event handler for the ItemDataBound event, or setup custom label items since then I also have to deal with setting up correct Style palettes so that the items have the correct colors.

This is how I'm setting up my Pie Series:

// Create my Pie series definition

SeriesMapping sMap = new SeriesMapping();

sMap.ChartAreaName = "_ChartArea"; // Custom layout chart area

sMap.CollectionIndex = SeriesIndex;

sMap.LegendLabel = sInfo.Title;

PieSeriesDefinition PieDefintion = new PieSeriesDefinition();

PieDefintion.LegendDisplayMode = LegendDisplayMode.DataPointLabel;

sMap.SeriesDefinition = PieDefintion;

// I tried mapping my "Label" item variable to both the DataPointMemeber Label and XCategory, in hopes that it would be picked up by the above LegendDisplayMode.

sMap.ItemMappings.Add(new ItemMapping("Label", DataPointMember.Label));

sMap.ItemMappings.Add(new ItemMapping("Label", DataPointMember.XCategory));

sMap.ItemMappings.Add(new ItemMapping("Value", DataPointMember.YValue));

// Add mapping

_RadChart.SeriesMappings.Add(sMap);

// My data is Updated at a later time, this code is just the series setup.

But I am still faced with "Item 0", "Item 1" etc... in my legend. There must be an elegant way to handle this that I am missing.

Thanks!