Class AggregateFunctionAttribute

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

Inheritance
System.Object
System.Attribute
AggregateFunctionAttribute
Namespace: Telerik.Reporting.Expressions
Assembly: Telerik.Reporting.dll

Syntax

[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public sealed class AggregateFunctionAttribute : Attribute, _Attribute
Examples

This example shows the usage of the attribute.

[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;
        }
    }
}

 _
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

Constructors

AggregateFunctionAttribute()

Initializes a new instance of the AggregateFunctionAttribute class.

Declaration
public AggregateFunctionAttribute()

Fields

Default

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

Declaration
public static readonly AggregateFunctionAttribute Default
Field Value
AggregateFunctionAttribute

Properties

Description

Gets the description of the aggregate function displayed in the expression builder.

Declaration
public string Description { get; set; }
Property Value
System.String

IsVisible

Gets a value indicating whether the aggregate should be shown at design time. Default value is true.

Declaration
public bool IsVisible { get; set; }
Property Value
System.Boolean

Name

Gets the name of the aggregate function as it should be used in the expressions.

Declaration
public string Name { get; set; }
Property Value
System.String

ReturnType

Gets or sets the return type of the aggregate function as it should be used in the expressions.

Declaration
public Type ReturnType { get; set; }
Property Value
System.Type

Methods

Equals(Object)

Indicates whether this attribute instance and a specified object are equal.

Declaration
public override bool Equals(object obj)
Parameters
System.Object obj

Another object to compare to.
Returns
System.Boolean

true if obj is equal to this instance; otherwise, false.
Overrides
System.Attribute.Equals(System.Object)

GetHashCode()

Returns the hash code for this attribute instance.

Declaration
public override int GetHashCode()
Returns
System.Int32

A 32-bit signed integer hash code.
Overrides
System.Attribute.GetHashCode()

IsDefaultAttribute()

Determines if this attribute is the default.

Declaration
public override bool IsDefaultAttribute()
Returns
System.Boolean

true if the attribute is the default value for this attribute class; otherwise, false.
Overrides
System.Attribute.IsDefaultAttribute()