I'm having trouble figuring out how to add a custom column type to a list with the object model.
SPFieldCollection.Add() has a parameter SPFieldType, but that must be one of the enumerated values in the Microsoft.SharePoint.SPFieldType enumeration, thus it cannot be used to create columns of a custom type.
I next attempted using SPFieldCollection.CreateNewField() but when I call SPField.Update() on the returned value I get an exception: "ArgumentException was unhandled. Value does not fall within the expected range.".
I see a reference to SPFieldCollection.AddFieldAsXml() here: How do I add custom column to existing WSS list template but there's hardly any info and I'm not sure that's the right track to take.
UPDATE: I found a post on AddFieldAsXml: http://weblogs.asp.net/bsimser/archive/2005/07/21/420147.aspx and it turns out it's very easy and worked well for me. Posting anyway in hopes it will help someone else.
SPFieldCollection.AddFieldAsXml() is the way to go as far as I can tell. See here for an example: http://weblogs.asp.net/bsimser/archive/2005/07/21/420147.aspx
Try with: SPField newField = null; newField= web.Fields.CreateNewField("MyFieldTypeName", fieldName); web.Fields.Add(newField); newField = web.Fields[fieldName]; // set some properties newField.ShowInDisplayForm = false; newField.ShowInViewForms = true; newField.Update();