Duplicating pie charts on postbacks? What's happening?

[LSUgirl]

Hi,

I have a single pie chart my page with some date range text boxes.  The user enters a date range and it populates the pie chart.  If the user selects another date range, it retrieves the data and creates a chart with 2 pie charts.  If the users searches again, I get 3 pie charts.  And so on.  What is going on?  The ldt is always created with one set of 7 rows.  It's not a data issue.

 My code behind:

 

Chart1.Data.Clear();

DataTable ldt = iPDDataAdapterTop5.RetrievePBToDt(0);

// if table has label, value, value use thisChart1.DataSourceSettings.Fields.Add(new FieldMap("code_desc", FieldUsage.Label));

Chart1.DataSourceSettings.Fields.Add(

new FieldMap("per_stds", FieldUsage.Value));Chart1.DataSourceSettings.Fields.Add(new FieldMap("nbr_stds", FieldUsage.NotUsed));

Chart1.DataSourceSettings.DataSource = ldt.DefaultView;

 

// do this to make mapping workSystem.IO.MemoryStream objStream = new System.IO.MemoryStream();

Chart1.Export(ChartFX.WebForms.

FileFormat.Jpeg, objStream);

Chart1.DataBind();

[Frank]

this code should be withing:

if (!IsPostBack) {

}

Otherwise you will be executing it every time a clallbsack/postpack occurs. In particular the problem is with the Fields collection. You are adding to it every time. If you want to start fresh you must do:

Chart1.Fields.Clear();

However, the IsPostBack check is a better option. You don't need to be doing any databinding again unless you need to.