Custom aggregate in Blazor Grid component

30 Oct 202315 minutes to read

The custom aggregate feature in Syncfusion’s Blazor Grid component allows you to calculate aggregate values using your own aggregate function. This feature can be useful in scenarios where the built-in aggregate functions do not meet your specific requirements. To use the custom aggregate option, follow the steps below:

  • Set the AggregateType as Custom in GridAggregateColumn component.

  • Provide your custom aggregate function in the customAggregate property.

The custom aggregate function will be invoked differently for total and group aggregations:

Total Aggregation: The custom aggregate function will be called with the whole dataset and the current aggregate column object as arguments.

Group Aggregation: The custom aggregate function will be called with the current group details and the aggregate column object as arguments.

Here’s an example that demonstrates how to use the custom aggregate feature in the Blazor Grid component:

@using Syncfusion.Blazor.Grids
@using BlazorApp1.Data

<SfGrid @ref="Grid" DataSource="@Orders" AllowPaging="true">
   <GridAggregates>
    <GridAggregate>
            <GridAggregateColumns>
                <GridAggregateColumn Field=@nameof(OrderData.ShipCountry) Type="AggregateType.Custom" >
                    <FooterTemplate>
                        @{
                            <div>
                                <p>Brazil Count: @CustomAggregateFunction()</p>
                            </div>
                        }
                    </FooterTemplate>
                </GridAggregateColumn>
            </GridAggregateColumns>
        </GridAggregate>
    </GridAggregates>    
    <GridColumns>
        <GridColumn Field=@nameof(OrderData.OrderID) HeaderText="Order ID" Width="120"></GridColumn>
        <GridColumn Field=@nameof(OrderData.CustomerID) HeaderText="Customer ID" Width="150"></GridColumn>
        <GridColumn Field=@nameof(OrderData.Freight) HeaderText="Freight" Format="C2" Width="120"></GridColumn>
        <GridColumn Field=@nameof(OrderData.ShipCountry) HeaderText="Ship Country" Width="150"></GridColumn>
    </GridColumns>
</SfGrid>
@code {
    private SfGrid<OrderData> Grid;
    public List<OrderData> Orders { get; set; }
  
    protected override void OnInitialized()
    {
        Orders = OrderData.GetAllRecords();
    }
    private int CustomAggregateFunction()
    {
        int Count = Queryable.Count(Orders.Where(x => x.ShipCountry.Contains("Brazil")).AsQueryable());
        return Count;
    }    
}
public class OrderData
    {
        public static List<OrderData> Orders = new List<OrderData>();
        public OrderData()
        {

        }
        public OrderData(int? OrderID, string CustomerID, string ShipCountry, DateTime OrderDate, double Freight)
        {
            this.OrderID = OrderID;
            this.CustomerID = CustomerID;   
            this.ShipCountry = ShipCountry;
            this.OrderDate = OrderDate;
            this.Freight = Freight;           
        }

        public static List<OrderData> GetAllRecords()
        {
            if (Orders.Count() == 0)
            {
                int code = 10;
                for (int i = 1; i < 2; i++)
                {
                    Orders.Add(new OrderData(10248, "ERNSH", "Austria",140.51));
                    Orders.Add(new OrderData(10249, "SUPRD", "Belgium",51.30));
                    Orders.Add(new OrderData(10250, "WELLI", "Brazil",65.83));
                    Orders.Add(new OrderData(10251, "HANAR", "France",58.17));
                    Orders.Add(new OrderData(10252, "WELLI", "Germany",13.97));
                    Orders.Add(new OrderData(10253, "HANAR", "Mexico",3.05));
                    Orders.Add(new OrderData(10254, "QUEDE", "Switzerland",32.38));
                    Orders.Add(new OrderData(10255, "RICSU", "Austria",41.34));
                    Orders.Add(new OrderData(10256, "WELLI", "Belgium",11.61));
                    code += 5;
                }
            }
            return Orders;
        }

        public int? OrderID { get; set; }
        public string CustomerID { get; set; }
        public double Freight { get; set; }
        public string ShipCountry { get; set; }
    }

To access the custom aggregate value inside template, use the key as Custom

Show the count of distinct values in aggregate row

You can calculate the count of distinct values in an aggregate row by using custom aggregate functions. By specifying the Type as Custom and providing a custom aggregate function in the CustomAggregate property, you can achieve this behavior.

Here’s an example that demonstrates how to show the count of distinct values for the ShipCountry column using a custom aggregate.

@using Syncfusion.Blazor.Grids
@using BlazorApp1.Data

<SfGrid @ref="Grid" DataSource="@Orders" AllowPaging="true">
    <GridAggregates>
        <GridAggregate>
            <GridAggregateColumns>
                <GridAggregateColumn Field=@nameof(OrderData.ShipCountry) Type="AggregateType.Custom">
                    <FooterTemplate>
                        @{

                            <div>
                                <p>Distinct Count: @CustomAggregateFunction()</p>
                            </div>
                        }
                    </FooterTemplate>
                </GridAggregateColumn>
            </GridAggregateColumns>
        </GridAggregate>
    </GridAggregates>
    <GridColumns>
        <GridColumn Field=@nameof(OrderData.OrderID) HeaderText="Order ID" Width="120"></GridColumn>
        <GridColumn Field=@nameof(OrderData.CustomerID) HeaderText="Customer ID" Width="150"></GridColumn>
        <GridColumn Field=@nameof(OrderData.Freight) HeaderText="Freight" Format="C2" Width="120"></GridColumn>
        <GridColumn Field=@nameof(OrderData.ShipCountry) HeaderText="Ship Country" Width="150"></GridColumn>
    </GridColumns>
</SfGrid>


@code {
    private SfGrid<OrderData> Grid;
    public List<OrderData> Orders { get; set; }
  
    protected override void OnInitialized()
    {
        Orders = OrderData.GetAllRecords();
    }
    private int CustomAggregateFunction()
    {
        int Count = Orders.Where(item => item.ShipCountry != null).Select(item => item.ShipCountry).Distinct().Count();
        return Count;
    }   
}
public class OrderData
    {
        public static List<OrderData> Orders = new List<OrderData>();
        public OrderData()
        {

        }
        public OrderData(int? OrderID, string CustomerID, string ShipCountry, double Freight)
        {
            this.OrderID = OrderID;
            this.CustomerID = CustomerID;   
            this.ShipCountry = ShipCountry;
            this.Freight = Freight;           
        }

        public static List<OrderData> GetAllRecords()
        {
            if (Orders.Count() == 0)
            {
                int code = 10;
                for (int i = 1; i < 2; i++)
                {
                    Orders.Add(new OrderData(10248, "ERNSH", "Austria", 140.51));
                    Orders.Add(new OrderData(10249, "SUPRD", "Belgium", 51.30));
                    Orders.Add(new OrderData(10250, "WELLI", "Brazil", 65.83));
                    Orders.Add(new OrderData(10251, "HANAR", "France", 58.17));
                    Orders.Add(new OrderData(10252, "WELLI", "Germany", 13.97));
                    Orders.Add(new OrderData(10253, "HANAR", "Mexico", 3.05));
                    Orders.Add(new OrderData(10254, "QUEDE", "Switzerland", 32.38));
                    Orders.Add(new OrderData(10255, "RICSU", "Austria", 41.34));
                    Orders.Add(new OrderData(10256, "WELLI", "Belgium", 11.61));
                    code += 5;
                }
            }
            return Orders;
        }

        public int? OrderID { get; set; }
        public string CustomerID { get; set; }
        public double Freight { get; set; }
        public string ShipCountry { get; set; }
    }

To display the aggregate value of the current column in another column, you can use the ColumnName property. If the ColumnName property is not defined, the field name value will be assigned to the ColumnName property.

You can refer to the Blazor DataGrid feature tour page for its groundbreaking feature representations. You can also explore Blazor DataGrid example to understand how to present and manipulate data.