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IGridSummaryItem Interface

An interface that defines a Grid summary item‘s API members (properties and methods).

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v21.2.dll

Declaration

public interface IGridSummaryItem

The following members accept/return IGridSummaryItem objects:

Remarks

We recommend that you use the IGridSummaryItem interface when you access a Grid summary item’s API members in any of the following cases:

  • You use the @ref attribute to reference a Grid summary item. For example, you set or change values of the Grid summary item’s parameters outside the markup.
  • You access an Item object from summary templates or event handlers.
  • You access elements of the Grid summary item collection. For example, the collection of Grid total summary items that is returned by the GetTotalSummaryItems() method.

In all other cases, bind your data to a summary item’s parameters.

The following code snippet handles the CustomizeSummaryDisplayText event to customize a custom summary item‘s text. The event’s Item argument (which returns an IGridSummaryItem object) provides access to the processed summary item.

@using Microsoft.EntityFrameworkCore
@inject IDbContextFactory<NorthwindContext> NorthwindContextFactory
@implements IDisposable

<DxGrid Data="GridDataSource"
        UnboundColumnData="Grid_CustomUnboundColumnData"
        CustomizeSummaryDisplayText="Grid_CustomizeSummaryDisplayText"
        CustomSummary="Grid_CustomSummary"
        AllowSelectRowByClick="true"
        SelectedDataItems="@SelectedDataItems"
        SelectedDataItemsChanged="Grid_SelectedDataItemsChanged"
        @ref="Grid">
    <Columns>
        <DxGridSelectionColumn />
        <DxGridDataColumn FieldName="ProductId" Caption="Product ID" DisplayFormat="d" />
        <DxGridDataColumn FieldName="UnitPrice" />
        <DxGridDataColumn FieldName="Quantity" />
        <DxGridDataColumn FieldName="Discount" DisplayFormat="p0" />
        <DxGridDataColumn FieldName="TotalPrice"
                          DisplayFormat="c"
                          UnboundType="GridUnboundColumnType.Decimal" />
    </Columns>
    <TotalSummary>
        <DxGridSummaryItem SummaryType="GridSummaryItemType.Custom" Name="Custom" FieldName="TotalPrice" />
    </TotalSummary>
</DxGrid>

@code {
    IEnumerable<object> GridDataSource { get; set; }
    NorthwindContext Northwind { get; set; }
    IReadOnlyList<object> SelectedDataItems { get; set; }
    IGrid Grid { get; set; }

    protected override void OnInitialized() {
        Northwind = NorthwindContextFactory.CreateDbContext();
        GridDataSource = Northwind.OrderDetails
            .Include(i => i.Order)
            .Include(i => i.Product)
            .ToList();
        SelectedDataItems = GridDataSource.Skip(1).Take(2).ToList();
    }

    void Grid_CustomSummary(GridCustomSummaryEventArgs e) {
        switch (e.SummaryStage) {
            case GridCustomSummaryStage.Start:
                e.TotalValue = 0m;
                break;
            case GridCustomSummaryStage.Calculate:
                if (e.Grid.IsDataItemSelected(e.DataItem))
                    e.TotalValue = (decimal)e.TotalValue + (decimal)e.GetRowValue("TotalPrice");
                break;
            case GridCustomSummaryStage.Finalize:
                e.TotalValueReady = true;
                break;
        }
    }

    void Grid_CustomizeSummaryDisplayText(GridCustomizeSummaryDisplayTextEventArgs e) {
        if (e.Item.Name == "Custom")
            e.DisplayText = string.Format("Sum of Selected: {0:c}", e.Value);
    }

    void Grid_CustomUnboundColumnData(GridUnboundColumnDataEventArgs e) {
        if (e.FieldName == "TotalPrice") {
            var UnitPrice = Convert.ToDecimal(e.GetRowValue("UnitPrice"));
            var Quantity = Convert.ToDecimal(e.GetRowValue("Quantity"));
            var Discount = Convert.ToDecimal(e.GetRowValue("Discount"));
            e.Value = Quantity * UnitPrice * (1 - Discount);
        }
    }

    void Grid_SelectedDataItemsChanged() {
        Grid.RefreshSummary();
    }

    public void Dispose() {
        Northwind?.Dispose();
    }
}

DevExpress Blazor Grid - Custom Summary

Run Demo: Grid - Custom Summary

See Also