old web2py blog

Consider:

db.recipe.category.requires=IS_IN_DB(db,'category.id','category.name')

The parameters are:

1. a set of records
2. category.id describes how the field will be represented in the database
3. category.name describes how the field will be represented to the user

For example you can do things like:

requires=IS_IN_DB(db(db.category.name.like('d%')),
                  'category.id',
                  'Name: %(name)s, id: %(id)s any text your like')