Progress® Telerik® Reporting R2 2018

AggregateFunctionAttribute Class

Used to specify the usage and the design time description of the aggregate function. This class cannot be inherited.

Inheritance Hierarchy

SystemObject
SystemAttribute
Telerik.Reporting.ExpressionsAggregateFunctionAttribute

Namespace: Telerik.Reporting.Expressions
Assembly: Telerik.Reporting (in Telerik.Reporting.dll)

Syntax

public sealed class AggregateFunctionAttribute : Attribute

Public NotInheritable Class AggregateFunctionAttribute
	Inherits Attribute

The AggregateFunctionAttribute type exposes the following members.

Constructors

	Name	Description
	AggregateFunctionAttribute	Initializes a new instance of the AggregateFunctionAttribute class.

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Properties

	Name	Description
	Description	Gets the description of the aggregate function displayed in the expression builder.
	IsVisible	Gets a value indicating whether the aggregate should be shown at design time. Default value is true.
	Name	Gets the name of the aggregate function as it should be used in the expressions.
	ReturnType	Gets or sets the return type of the aggregate function as it should be used in the expressions.

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Methods

	Name	Description
	Equals	Indicates whether this attribute instance and a specified object are equal. (Overrides AttributeEquals(Object).)
	GetHashCode	Returns the hash code for this attribute instance. (Overrides AttributeGetHashCode.)
	IsDefaultAttribute	Determines if this attribute is the default. (Overrides AttributeIsDefaultAttribute.)

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Fields

	Name	Description
	Default	Returns the default instance of the attribute with all its properties set to default values.

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Examples

This example shows the usage of the attribute.

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[AggregateFunction(Description = "Concatenation aggregate. Output: (value1, value2, ...)", Name = "Concatenate")]
class ConcatenateAggregate : IAggregateFunction
{
    string result;

    public void Accumulate(object[] values)
    {
        // The aggregate function expects one parameter
        object value = values[0];

        // null values are not aggregated
        if (null == value)
        {
            return;
        }

        // The actual accumulation
        if (this.result.Length > 0)
        {
            result += ", ";
        }
        this.result += value.ToString();
    }

    public object GetValue()
    {
        return string.Format("({0})", this.result);
    }

    public void Init()
    {
        // Add aggregate function initialization code here if needed
        this.result = string.Empty;
    }

    public void Merge(IAggregateFunction aggregateFunction)
    {
        ConcatenateAggregate aggregate = (ConcatenateAggregate)aggregateFunction;

        if (aggregate.result.Length > 0)
        {
            if (this.result.Length > 0)
            {
                result += ", ";
            }
            this.result += aggregate.result;
        }
    }
}

<AggregateFunction(Description:="Concatenation aggregate. Output: (value1, value2, ...)", Name:="Concatenate")> _
Class ConcatenateAggregate
    Implements IAggregateFunction
    Private result As String

    Public Sub Accumulate(ByVal values As Object()) Implements IAggregateFunction.Accumulate
        ' The aggregate function expects one parameter
        Dim value As Object = values(0)

        ' null values are not aggregated
        If value Is Nothing Then
            Return
        End If

        ' The actual accumulation
        If Me.result.Length > 0 Then
            result += ", "
        End If
        Me.result += value.ToString()
    End Sub

    Public Function GetValue() As Object Implements IAggregateFunction.GetValue
        Return String.Format("({0})", Me.result)
    End Function

    Public Sub Init() Implements IAggregateFunction.Init
        ' Add aggregate function initialization code here if needed
        Me.result = String.Empty
    End Sub

    Public Sub Merge(ByVal aggregateFunction As IAggregateFunction) Implements IAggregateFunction.Merge
        Dim aggregate As ConcatenateAggregate = DirectCast(aggregateFunction, ConcatenateAggregate)

        If aggregate.result.Length > 0 Then
            If Me.result.Length > 0 Then
                result += ", "
            End If
            Me.result += aggregate.result
        End If
    End Sub
End Class