How to assign the update method with class param of ObjectDataSour

[Guest]

The type ObjectDataSource1.UpdateParameters[0].DefaultValue is string.
However, the update method of the ObjectDataSource1 is a class:

[DataObjectMethod(DataObjectMethodType.Update)]
public void UpdateEvent(EventInfo eventInfo)
{
dal.UpdateEvent(eventInfo);
}


protected void DataList1_UpdateCommand(object source,
DataListCommandEventArgs e)
{
//ObjectDataSource1.UpdateParameters[0].DefaultValue = ????
ObjectDataSource1.Update();

DataList1.EditItemIndex = -1;
DataList1.DataBind();
}