Unbound Columns

• Oct 29, 2020
• 3 minutes to read

This topic describes the main concepts of using unbound columns within the GridView extension.

Unbound Columns Overview

GridView supports both bound and unbound columns. Bound columns obtain their data from a data source. Unbound columns are not bound to any field in a data source. These columns can be populated manually by handling the GridViewSettings.CustomUnboundColumnData event or by specifying an expression via the GridViewDataColumn.UnboundExpression used to evaluate values for this field. The Expressions section describes the syntax for creating expressions.

There is no difference between working with bound and unbound columns. You can sort, group, display summaries and filter unbound columns in the same manner as bound columns.

An unbound column meets the following requirements.

• Its GridViewDataColumn.FieldName property must be set to a unique value and not refer to any field in the GridView ‘s data source.
• The column’s GridViewDataColumn.UnboundType property must be set to an appropriate value based on the type of data the column is supposed to display (Boolean, DateTime, Decimal, Integer, String, Object). It should not be set to UnboundColumnType.Bound.

Providing Data for Unbound Columns

ASP.NET MVC GridView provides two approaches to generate data for unbound columns.

• Using an Unbound Expression

• Using a Delegate Method

When the GridView extension is bound to a data source in Database Server Mode, you can only enable sorting, grouping, filtering and summary calculation for unbound columns that are populated with unbound expressions.

Note

The GridViewSettings.CustomUnboundColumnData event’s ASPxGridColumnDataEventArgs.IsSetData parameter isn’t in effect.

Limitations

• The grid cannot sort or group unbound columns whose GridViewDataColumn.UnboundType property is set to Object.