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How to remove columns using DataSourceSettings.Fields collection


eric.m.smith
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I have a DataTable that I am trying to filter to display multiple pie charts from one set. I am able to filter my data using a DataView but once the data is assigned to the Chart, I want to remove the filtered column from the bound fields. I want to do this because the filtered data is being used as labels when I want other fields from the dataview.

 In my sample code below. I want to remove the "REGION" column so that my labels are pulled from the "TYPE" column. If I try to do this by removing the REGION from usage, the chart displays no data. How can I do this? Is there a completely different approach to doing this in the chart? I know i can do this my manually building a new Data Table that doesnt contain the "REGION" column, but it looks like the chart should be able to exclude the column for me.

 Thanks - Eric Smith 

 [replace page_load of a blank aspx page to run the code]

  protected void Page_Load(object sender, EventArgs e)   {   ChartFX.WebForms.Chart cht = new ChartFX.WebForms.Chart();   cht.Gallery = ChartFX.WebForms.Gallery.Pie;   System.Data.DataTable dt = new DataTable();   dt.Columns.Add("REGION", System.Type.GetType("System.String"));   dt.Columns.Add("TYPE", System.Type.GetType("System.String"));   dt.Columns.Add("PCT", System.Type.GetType("System.Int16"));   dt.Rows.Add(new object[] { "R1", "O", 20 });   dt.Rows.Add(new object[] { "R1", "W", 80 });   dt.Rows.Add(new object[] { "R2", "O", 50 });   dt.Rows.Add(new object[] { "R2", "W", 50 });     //cht.DataSourceSettings.Fields.Add(new ChartFX.WebForms.FieldMap("REGION", ChartFX.WebForms.FieldUsage.NotUsed));   cht.DataSource = new System.Data.DataView(dt, "REGION='R1'", "", DataViewRowState.CurrentRows);   form1.Controls.Add(cht);   } 

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If there is no elegant way to do this using the ChartFX API you may want to consider:

Filtering the data in DataView #1

Pushing DataView #1 to new DataTable #2

Removing the columns you don't want from DataTable #2

Creating DataView #3 based on DataTable #2

Binding DataView #3 to the chart (or you could skip this step and bind DataTable #2)

Definitely a kludge but it will work.

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cht.DataSourceSettings.Fields is empty by default.

If at the time of DataBinding, the Fields collection is empty, the fields collection is read from the schema.

If you want only a few fields to be display you must Add (not remove) these to the Fields collection. You add the ones you want (as opposed to removing those you don't).

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