Unbound Columns

You can create unbound columns to display custom information in the DataGrid control. An unbound column is not bound to a field in the underlying data source. You should populate this column with data manually, using the DataGridControl.CustomUnboundColumnData event.

To create an unbound column, do the following:

Create a GridColumn object.
Set the column's UnboundDataType property to the type of data this column is intended to display.
Set the column's FieldName property to a unique field name.
Add the column to the DataGridControl.Columns collection, using the Add or Insert method. You can also position the column with the GridColumn.VisibleIndex property.

Note that the control does not store or cache data for unbound columns. It invokes the CustomUnboundColumnData event, which you need to handle to specify data for unbound columns.

The CustomUnboundColumnData event fires in two cases:

When DataGrid needs to display a cell value in an unbound column. In this case, the IsGettingData event parameter returns true. You need to assign a value to the Value event parameter.
When a user changes data in an unbound column's cells. In this case, the IsGettingData event parameter returns false. Read the Value event parameter and cache it manually in your storage for further use.

Example 1

The following example creates an unbound read-only Total column, and handles the CustomUnboundColumnData event to calculate column values based on values of other fields, according to the expression: Total=UnitPrice*Quantity. The event handler checks the IsGettingData event parameter, and retrieves values when this parameter is true.

xmlns:mxdg="https://schemas.eremexcontrols.net/avalonia/datagrid"
xmlns:sys="clr-namespace:System;assembly=System.Runtime"
...
<mxdg:DataGridControl Grid.Column="5" Width="400" Name="dataGrid1" 
 CustomUnboundColumnData="dataGrid1_CustomUnboundColumnData" >
    <mxdg:DataGridControl.Columns>
        <mxdg:GridColumn Name="colUnitPrice" FieldName="UnitPrice" 
         Header="Unit Price" Width="*"  />
        <mxdg:GridColumn Name="colQuantity" FieldName="Quantity" 
         Header="Quantity" Width="*"/>
        <mxdg:GridColumn Name="colTotal" FieldName="Total" Header="Total" 
         Width="*" ReadOnly="True" UnboundDataType="{x:Type sys:Decimal}" />
    </mxdg:DataGridControl.Columns>
</mxdg:DataGridControl>

List<PurchaseRecord> list = new List<PurchaseRecord>();
list.Add(new PurchaseRecord() { UnitPrice = 1.3m, Quantity = 2 });
list.Add(new PurchaseRecord() { UnitPrice = 4m, Quantity = 1 });
list.Add(new PurchaseRecord() { UnitPrice = 10m, Quantity = 20 });
list.Add(new PurchaseRecord() { UnitPrice = 7m, Quantity = 12 });

dataGrid1.ItemsSource = list;

private void dataGrid1_CustomUnboundColumnData(object? sender, DataGridUnboundColumnDataEventArgs e)
{
    if (e.IsGettingData && e.Column.FieldName == "Total")
    {
        PurchaseRecord rec = e.Item as PurchaseRecord;
        if (rec != null)
        {
            e.Value = rec.Quantity * rec.UnitPrice;
        }
    }
}

public partial class PurchaseRecord : ObservableObject
{
    [ObservableProperty]
    decimal unitPrice;
    [ObservableProperty]
    int quantity;
}

Table of Contents

Unbound Columns

Example 1