Version 13 (modified by Fran Boon, 12 years ago) ( diff )

no longer limited to int

IS_ONE_OF Validator

(For large lookup tables use IS_ONE_OF_EMPTY)

The IS_ONE_OF() validator is a custom version of web2py's IS_IN_DB() for foreign key lookups in a key table. In forms, the respective field will be rendered as a drop-down field.

Unlike IS_IN_DB, the IS_ONE_OF validator is deletion status sensitive, i.e. records in the key table that are flagged as 'deleted' will be ignored.

Furthermore, it is possible to filter the key records by a type field for certain options.


db.table.field.requires = IS_ONE_OF(db, "keytable.keyfield", represent, filterby="fieldname", filter_opts=options)

  • keytable = Name of the key table
  • keyfield = Name of the key field
  • represent = how to build the option label (in drop-downs in forms) from the key entry, one of the following:
    • string template, e.g. "%(first_name)s %(last_name)s"
    • list or tuple of field names, e.g. ('first_name', 'last_name')
    • function or lambda, e.g. lambda r: "%(first_name)s %(last_name)s" % dict(r)
  • filterby="fieldname" = the type field to filter for
  • filter_opts="options" = a list or tuple of allowed values for the filterby-field


  • Without represent and if no 'name' field can be detected in the table, the keyfield itself will be used as option label.
  • If filterby is specified, the drop-down fields get sorted by this field (unless overriden by orderby).
  • IS_ONE_OF can be cascaded through IS_NULL_OR to include empty selection


db[table].pe_id.requires = IS_NULL_OR(IS_ONE_OF(db,
    "pr_pentity.pe_id",                       # key table=pr_pentity, key field=pe_id
    shn_pentity_represent,                    # function to represent a pr_pentity entry as string
    filterby="instance_type",                 # type field in the pr_pentity table
    filter_opts=("pr_person",),               # select only entries with instance_type in ("pr_person",) (select only persons)
    orderby="pr_pentity.pe_id"                # NB Need explicit orderby, otherwise it orders by all fields!


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