Timespan Sum Aggregation Function

[Adam]

When I try to apply the Summ Aggregation function to a column containing Timespans I get the following exception:

"No generic method 'Sum' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic."

My column declaration looks like this:

 

<telerikGridView:GridViewDataColumn Header="Duration" UniqueName="Duration">
    <telerikGridView:GridViewDataColumn.AggregateFunctions>
        <data:SumFunction Caption="Total: " />
    </telerikGridView:GridViewDataColumn.AggregateFunctions>
</telerikGridView:GridViewDataColumn>

 

Can anyone point me in the right direction or an example of a custom aggregation faunction, if that's what I need to do?

Thanks.

 

 

 

[Milan]

Hi Adam,

RadGridView uses the standard extension methods like Sum, Average, etc to calculate the result of its aggregate function and if such methods are not defined an exception is thrown. 

The solution is to create a simple custom aggregate function to do the job:

public class TimeSpanSumFunction : EnumerableSelectorAggregateFunction
{
    protected override string AggregateMethodName
    {
        get
        {
            // which method of the ExtensionMethodsType will handle the summation
            return "Sum";
        }
    }

    // assign new type to handle summation
    protected override Type ExtensionMethodsType
    {
        get
        {
            return typeof(Statistics);
        }
    }
}

public static class Statistics
{
    public static TimeSpan Sum<T, TTimeSpan>(IEnumerable<T> source, Func<T, TimeSpan> selector)
    {
        return source.Select(selector).Aggregate(TimeSpan.Zero, (t1, t2) => t1 + t2);
    }
}

One the custom function is ready it is straightforward to use:

<telerik:GridViewDataColumn Header="Position" DataMemberBinding="{Binding Position}">
            <telerik:GridViewDataColumn.AggregateFunctions>
                <local:TimeSpanSumFunction SourceField="Position"/>
            </telerik:GridViewDataColumn.AggregateFunctions>
        </telerik:GridViewDataColumn>
</telerik:GridViewDataColumn>

Greetings,
Milan
the Telerik team

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[Camron]

Milan,

I am still encountering the problem Adam was encountering even after implementing your solution. Perhaps you can help? I am using Blend 4 Ultimate and VS2010 to develop a prototype.

My XAML:

    <Grid x:Name="LayoutRoot" Background="White" DataContext="{Binding Source={StaticResource JobGLSummaryCurrent}}">
        <telerik:RadGridView DataContext="{Binding Collection}" ItemsSource="{Binding}" >
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding JobNo}" Header="Job"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Type}" Header="Type"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding CostCode}" Header="Cost Type"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Actuals}" Header="Actuals (Inc. Accruals)" DataFormatString="{}{0:c}">
                    <telerik:GridViewDataColumn.AggregateFunctions>
                        <local:SumFunction/>
                    </telerik:GridViewDataColumn.AggregateFunctions>
                </telerik:GridViewDataColumn>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Budget}" Header="Budget (Inc. CO's)"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding BudRem}" Header="Bud. Rem."/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding BudPercentRem}" Header="% Bud. Rem."/>
            </telerik:RadGridView.Columns>
        </telerik:RadGridView>
    </Grid>

My C# classes:

    public class SumFunction : EnumerableSelectorAggregateFunction
    {

        protected override string AggregateMethodName
        {
            get { return "Sum"; }
        }

        protected override Type ExtensionMethodsType
        {
            get
            {
                return typeof (Amounts);
            }
        }
    }

    public static class Amounts
    {
        public static double Sum<T, TDouble>(IEnumerable<T> source, Func<T, System.Double> selector)
        {
            return source.Select(selector).Aggregate(Double.Parse("0"), (t1, t2) => t1 + t2);
        }
    }

I'm using the latest version as of this post. The target version is Silverlight 4.

I still receive the error when I implement the solution you suggested. Once I take the Aggregate function out of the column, everything works fine. I am binding to a sample data source made in Blend. The DataType value of the GridViewDataColumn is "System.Double", which is automatically put in by Blend after I bind the collection I'm using.

Any help on this matter would be appreciated.

Camron

[Vlad]

Hello Camron,

 Do you have our latest service pack (Q1 2010 SP2)? Please post more info about the grid version. 

Kind regards,
Vlad
the Telerik team

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[Camron]

Vlad,

I have "RadControls for Silverlight Q1 2010 SP2" installed. As a note, I also have "RadControls for WinForms Q1 2010" installed alongside (just in case that makes a difference).

I am using the following references:

Telerik.Windows.Controls

Telerik.Windows.Controls.Gridview

Telerik.Windows.Controls.Input

Telerik.Windows.Controls.Data

All are version 2010.1.603.1040 with a runtime version of v2.0.50727.

Camron

[Vlad]

Hello Camron,

 Sorry - I've missed that SourceField is not specified. Please set this to desired property to avoid this error.

Kind regards,
Vlad
the Telerik team

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[Camron]

Vlad,

The error is still occuring.

 <Grid x:Name="LayoutRoot" Background="White" DataContext="{Binding Source={StaticResource JobGLSummaryCurrent}}">
        <telerik:RadGridView DataContext="{Binding Collection}" ItemsSource="{Binding}" >
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding JobNo}" Header="Job"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Type}" Header="Type"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding CostCode}" Header="Cost Type"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Actuals}" Header="Actuals (Inc. Accruals)">
                    <telerik:GridViewDataColumn.AggregateFunctions>
                        <local:SumFunction SourceField="Actuals"/>
                    </telerik:GridViewDataColumn.AggregateFunctions>
                </telerik:GridViewDataColumn>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Budget}" Header="Budget (Inc. CO's)"/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding BudRem}" Header="Bud. Rem."/>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding BudPercentRem}" Header="% Bud. Rem."/>
            </telerik:RadGridView.Columns>
        </telerik:RadGridView>
    </Grid>

[Vlad]

Hello Camron,

 Can you send us an example project (via support ticket) demonstrating this problem? 

Sincerely yours,
Vlad
the Telerik team

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[David Cronin]

Vlad,

The ticket number is 319174. I had to submit it via our development account.

Camron

[Vlad]

Camron,

 I saw the ticket however in your project your are trying to call Sum for Property1 which is string. You cannot do that.

Regards,
Vlad
the Telerik team

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[Maya]

Hello David Cronin,

The problem here is in the definition of your custom function. So, instead of defining it as follow:

public static class Statistics
   {
       public static Double Sum<T, TDouble>(IEnumerable<T> source, Func<T, Double> selector)
       {
        return source.Select(selector).Aggregate(Double.MaxValue, (t1, t2) => t1 + t2);
       }
   }

You need to remove the second parameter in Sum<>:

public static class Statistics
    {
        public static Double Sum<T>(IEnumerable<T> source, Func<T, Double> selector)
        {
         return source.Select(selector).Aggregate(Double.MaxValue, (t1, t2) => t1 + t2);
        }
    }

 

All the best,
Maya
the Telerik team

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[Camron]

Thank you, Maya. The problem is no longer present. Thank you for your support!