Silverlight : How to bind a result of loadoperation to LineSeries chart which contains few null values - wpf

Question

I have bound a my chart to a result of load operation. The result returned by the load operation returns complex type with values for some of the object's properties is null.
So I am getting an error in my silver light application.
The code of my XAML is as follows:
<Grid x:Name="LayoutRoot">
<toolkit:Chart Name="historicalTotalChart" Title="Chart Title">
<toolkit:LineSeries >
</toolkit:LineSeries>
</toolkit:Chart>
</Grid>
Code of in my CS file is as follows:
LoadOperation<GetHistoricalTotalReport_Result> hisTotalsLoadOp =
context.Load(context.GetHistoricalToalReportQuery(tableName, sD, startDate, endDate));
LineSeries line = new LineSeries();
line.ItemsSource = hisTotalsLoadOp.Entities;
//line.DependentValuePath ="rep_date";
//line.IndependentValuePath = "expr1";
line.DependentValueBinding = new Binding("[rep_date]");
line.IndependentValueBinding = new Binding("[expr1]");
line.Title = "Historical Totals";
historicalTotalChart.Series.Add(line);
Can any one say how can I over come this error?
rep_date, expr1 are the properties with in my complex type GetHistoricalTotalReport_Result. I am I binding to the properties correctly?
Any help much appreciated.
Thanks

Answer 1

There are 3 possible issues in your application:
Your bindings shouldn't contain square brackets, they are for arrays and dictionaries. Also I would rather use the properties Dependent/IndependentValuePath, you shouldn't comment them, they are completely correct.
The DependentValuePath property must be of a numerical data type, because it is situated on the Y-axis. In your example the rep_date property could be of the double type.
The IndependentValuePath is situated on the X-axis and could be of any type but the values can't contain nulls. Really, I have no idea where a null value can be displayed on the X-axis, it doesn't make sense.
Here is the example of the correct code which works fine:
LineSeries line = new LineSeries();
line.ItemsSource = new[]
{
new ItemViewModel{expr1 = "Item1", rep_date = 25},
new ItemViewModel{expr1 = "Item2", rep_date = null},
new ItemViewModel{expr1 = "Item3", rep_date = 31},
new ItemViewModel{expr1 = "Item4", rep_date = null},
};
line.DependentValuePath = "rep_date";
line.IndependentValuePath = "expr1";
line.Title = "Historical Totals";
historicalTotalChart.Series.Add(line);
The next code will not work:
line.ItemsSource = new[]
{
new ItemViewModel{expr1 = null, rep_date = 25} //wrong, x-value can't be null
}
But you can filter your entities before displaying them:
line.ItemsSource = hisTotalsLoadOp.Entities.Where(e => e.expr1 != null).ToList();