SharePoint 2007 Custom Fields and “Edit property on server”

When developing custom fields in SharePoint 2007 you may encounter this warning when adding the field to a document library but not to a list:

“The field type cannot be edited from most client programs and might block the programs from saving documents to this library.”

The warning is given because an ASPX control is used for editing the column/property values in SharePoint but this ASPX control cannot be used for editing column values in client applications such as Microsoft Word. When a document is created in Microsoft Word the column is shown with the “Edit property on server” error:

To allow the column to be edited in client applications you need to specify a parent type for the field. This parent type is one of the standard field types that a client application can edit. You then specify that the parent type edit mechanism (such as a standard edit box or combo box) can be used by setting the AllowBaseTypeRendering property for the field.

To do this edit the fldtypes_*xml file for the custom field; add the AllowBaseTypeRendering Field element with the value “TRUE” and set the ParentType field element to a standard field type, such as “Number”:

<Field Name=“TypeName“>RatingField</Field>

<Field Name=“ParentType“>Number</Field>

<Field Name=“SQLType“>float</Field>

<Field Name=“TypeDisplayName“>Rating Field</Field>

<Field Name=“TypeShortDescription“>Rating Field</Field>

<Field Name=“Sortable“>TRUE</Field>

<Field Name=“AllowBaseTypeRendering“>TRUE</Field>

<Field Name=“Filterable“>TRUE</Field>

The field will now be editable in client applications like Microsoft Word.