Custom aggregate signature

[David]

I am trying to implement a custom aggregate function so I can use values from multiple columns.

The GridView is bound to a collection of row ViewModels which expose a set of properties of type double.

I have created a custom aggregate function:

public class CustomAggregateFunction : EnumerableSelectorAggregateFunction

    {

        protected override string AggregateMethodName

        {

            get { return "CustomAggregate"; }

        }

        protected override Type ExtensionMethodsType

        {

            get { return typeof (CustomAggregateCalculator); }

        }

    }

I am struggling with the signature of the aggregation method, the following:

public static class CustomAggregateCalculator 

    {

        public static double CustomAggregate<TSource>(this IEnumerable<TSource> source, Func<TSource, double> selector)

        {

            return 0;

        }

    }

Gives me the following exception:

System.InvalidOperationException occurred

  Message=No method 'CustomAggregate' on type 'IntelHedgerGUI.ViewModel.CustomAggregateCalculator' is compatible with the supplied arguments.

  Source=System.Core

  StackTrace:

       at System.Linq.Expressions.Expression.FindMethod(Type type, String methodName, Type[] typeArgs, Expression[] args, BindingFlags flags)

       at System.Linq.Expressions.Expression.Call(Type type, String methodName, Type[] typeArguments, Expression[] arguments)

       at Telerik.Windows.Data.Expressions.EnumerableSelectorAggregateFunctionExpressionBuilder.CreateMethodCallExpression(LambdaExpression memberSelectorExpression) in c:\Builds\WPF_Scrum\Release_WPF_2010_Q2\Sources\Development\Core\Data\Expressions\Grouping\Aggregates\EnumerableSelectorAggregateFunctionExpressionBuilder.cs:line 48

What signature should the CustomAggregate method have?

[Maya]

Hi David,

In order to provide you with an appropriate solution, we would need more details. Mainly, about the source for that Aggregate Function, its SourceField and the basic settings of the project. It would be great if you could send us a sample project or at least paste some of your code here.
 

All the best,
Maya
the Telerik team