Using DataPointMember.XValue vs. DataPointMember.XCategory

[Eric]

I am binding my chart to a DataTable.  Using the following code in the chart's constructor to display two bar series works:

SeriesMapping histCostSeriesMapping = new SeriesMapping { LegendLabel = "Historic Cost", SeriesDefinition = new BarSeriesDefinition()};

histCostSeriesMapping.ItemMappings.Add(new ItemMapping("YEAR", DataPointMember.XCategory));

histCostSeriesMapping.ItemMappings.Add(new ItemMapping("HISTCOST", DataPointMember.YValue));

chart.SeriesMappings.Add(histCostSeriesMapping);

  

SeriesMapping replCostSeriesMapping = new SeriesMapping { LegendLabel = "Replacement Cost", SeriesDefinition = new BarSeriesDefinition()};

replCostSeriesMapping.ItemMappings.Add(new ItemMapping("YEAR", DataPointMember.XCategory));

replCostSeriesMapping.ItemMappings.Add(new ItemMapping("REPLCOST", DataPointMember.YValue));

chart.SeriesMappings.Add(replCostSeriesMapping);

chart.ItemsSource = _model.Data;

However, if I replace both instances of DataPointMember.XCategory with DataPointMember.XValue, I get the following error:

InvalidOperationException - The binary operator GreaterThanOrEqual is not defined for the types 'System.Object' and 'System.Double'.

Also if I use just one series on the chart (with DataPointMember.XValue), it works fine. 

[Yavor]

Hello Eric,

I tested the functionality, which you mentioned, and the control behaved as expected. Attached to this message, is the code, which I used for testing. You can take a look at it, and let me know whether this is the expected behavior. You can also use this as the initial setup, to replicate any erroneous behavior, and post the code back.

Greetings,
Yavor
the Telerik team

[Eric]

Hi Yavor,

The example you provided only maps one data series, and it uses DataPointMember.XCategory instead of DataPointMember.XValue, so it does not demonstrate the issue I am having.

The modified code which replicates the error is as follows:

private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
    //radChart.ItemsSource = TradeData.GetWeeklyData("MSFT");
    radChart.ItemsSource = TradeData.GetDataTable();

    mapping1 = new SeriesMapping();
    mapping1.SeriesDefinition = new LineSeriesDefinition();

    ItemMapping itemmapping1 = new ItemMapping("High", DataPointMember.YValue);
    mapping1.ItemMappings.Add(itemmapping1);
    ItemMapping temp1 = new ItemMapping("Year", DataPointMember.XValue);
    mapping1.ItemMappings.Add(temp1);

    radChart.SeriesMappings.Add(mapping1);

    mapping2 = new SeriesMapping();
    mapping2.SeriesDefinition = new LineSeriesDefinition();

    ItemMapping itemmapping2 = new ItemMapping("Low", DataPointMember.YValue);
    mapping2.ItemMappings.Add(itemmapping2);
    ItemMapping temp2 = new ItemMapping("Year", DataPointMember.XValue);
    mapping2.ItemMappings.Add(temp2);

    radChart.SeriesMappings.Add(mapping2);

    radChart.Rebind();
}

public static DataTable GetDataTable() {
    DataTable tradeData = new DataTable("TradeData");

    DataColumn myColumn = new DataColumn();
    myColumn.DataType = System.Type.GetType("System.Int32");
    myColumn.AllowDBNull = false;
    myColumn.Caption = "Year";
    myColumn.ColumnName = "Year";
    tradeData.Columns.Add(myColumn);
    myColumn = new DataColumn();
    myColumn.DataType = System.Type.GetType("System.Decimal");
    myColumn.AllowDBNull = false;
    myColumn.Caption = "High";
    myColumn.ColumnName = "High";
    tradeData.Columns.Add(myColumn);
    myColumn = new DataColumn();
    myColumn.DataType = System.Type.GetType("System.Decimal");
    myColumn.AllowDBNull = false;
    myColumn.Caption = "Low";
    myColumn.ColumnName = "Low";
    tradeData.Columns.Add(myColumn);

    DataRow myRow;
    for (int i = 0; i < 100; i++) {
        myRow = tradeData.NewRow();
        myRow[0] = 1900 + i + 1;
        myRow[1] = i + 5;
        myRow[2] = i + 7;
        tradeData.Rows.Add(myRow);
    }
    return tradeData;
}

One thing to note is that the error does not occur if I map to an ObservableCollection, but it does occur if I map to a DataTable.

[Ves]

Hi Eric,

Thanks for this  clarification. Indeed, when using DataTable you need to provide the field type for the item mappings. Please, find attached a small example which works as expected

Best regards,
Ves
the Telerik team

[Eric]

Thanks, that works well.