James Gregory

The version of the ObjectField that this post refers to is now out of date. Please go to the ObjectField 1.1 post for the latest version.

I encountered a problem while binding a complex object to a GridView, in that the BoundField doesn’t support specifying a nested value in it’s DataField property. So if you have a list of Customer’s, and want to display the TelephoneNumber property from inside the customer’s ContactDetails property, you’re out of luck.

<asp:BoundField DataField="ContactDetails.TelephoneNumber" />

The above would fall over with an exception along the lines of: A field or property with the name 'ContactDetails.TelephoneNumber' was not found on the selected data source.

This is a mind-boggling flaw in the BoundField, with the main solution being to create a nested GridView, which is just overkill for most situations. This problem especially rears it’s ugly head if you’re using an ORM layer such as NHibernate or SubSonic.

So what have I done? I’ve just gone and created a solution to this problem.

Introducing the ObjectField, a GridView field that allows binding against hierarchical structured objects. In short, it takes a BoundField and splits it on full-stops (periods!) using each element to find an object.

<jag:ObjectField DataField="ContactDetails.TelephoneNumber" />

The above is now possible! Huzzah.

Extras

There’s one extra thing you should know about. The field has a couple of additional properties that can be useful.

The first is AllowNulls which defaults to true, this will make the field return silently when a null is encountered anywhere along the object hierarchy; this can be useful if you know that there might be a null somewhere along the lines.

The second property is NullValue, which is displayed by the field when AllowNulls is true and a null is encountered. Setting this value allows you to give a user-friendly message if a value is null.

Downloads

The ObjectField is open-source under the new BSD License; read the license for what you’re allowed to do.