Class CustomAggregators

Provides methods that manipulate custom aggregators.

Inheritance

Object

CustomAggregators

Namespace: DevExtreme.AspNet.Data.Aggregation

Assembly: DevExtreme.AspNet.Data.dll

Syntax

public static class CustomAggregators

Remarks

When implementing a custom data aggregator, derive it from the Aggregator<T> class as shown in the following example. The custom aggregator in it calculates total sales:

class TotalSalesAggregator<T> : Aggregator<T> {
    decimal _total = 0;

    public TotalSalesAggregator(IAccessor<T> accessor)
        : base(accessor) {
    }

    public override void Step(T container, string selector) {
        var quantity = Convert.ToInt32(Accessor.Read(container, "Quantity"));
        var unitPrice = Convert.ToDecimal(Accessor.Read(container, "UnitPrice"));
        var discount = Convert.ToDecimal(Accessor.Read(container, "Discount"));
        _total += quantity * unitPrice * (1 - discount);
    }

    public override object Finish() {
        return _total;
    }
}

Then, register the aggregator under a string identifier at the application's start (for instance, in Global.asax or Startup.cs):

CustomAggregators.RegisterAggregator("totalSales", typeof(TotalSalesAggregator<>));

Important

Custom aggregators are ignored if the LINQ provider groups data and calculates summaries. Set RemoteGrouping to false for custom aggregators to apply.

Methods

RegisterAggregator(String, Type)

Registers a custom aggregator.

Declaration

public static void RegisterAggregator(string summaryType, Type aggregatorType)

Parameters

Type	Name	Description
String	summaryType	The aggregator's string identifier.
Type	aggregatorType	The aggregator's type declaration without the generic type parameter T.