Validators

norman.validate.ifset(func)

Return func(value) if value is not NotSet, otherwise return `NotSet.

This is normally used as a wrapper around another validator to permit NotSet values to pass. For example:

>>> validator = ifset(istype(float))
>>> validator(4.3)
4.3
>>> validator(NotSet)
NotSet
>>> validator(None)
Traceback (most recent call last):
    ...
TypeError: None

norman.validate.isfalse(func[, default])

Return a Field validator which passes if func returns False.

Parameters:

• func – A callable which returns False if the value passes.
• default – The value to return if func returns True. If this is omitted, an exception is raised.

norman.validate.istrue(func[, default])

Return a Field validator which passes if func returns True.

Parameters:

• func – A callable which returns True if the value passes.
• default – The value to return if func returns False. If this is omitted, an exception is raised.

norman.validate.istype(t[, t2[, t3[, ...]]])

Return a Field validator which raises an exception on an invalid type.

Parameters:t – The expected type, or types.

norman.validate.settype(t, default)

Return a Field validator which converts the value to a type

Parameters:

• t – The required type.
• default – If the value cannot be converted, then use this value instead.

norman.validate.todate([fmt])

Return a validator which converts a string to a datetime.date.

If fmt is omitted, the ISO representation used by datetime.date.__str__ is used, otherwise it should be a format string for datetime.strptime.

If the value passed to the validator is a datetime.datetime, the date component is returned. If it is a datetime.date it is returned unchanged.

The return value is always a datetime.date object. If the value cannot be converted an exception is raised.

norman.validate.todatetime([fmt])

Return a validator which converts a string to a datetime.datetime.

If fmt is omitted, the ISO representation used by datetime.datetime.__str__ is used, otherwise it should be a format string for datetime.strptime.

If the value passed to the validator is a datetime.datetime it is returned unchanged. If it is a datetime.date or datetime.time, it is converted to a datetime.datetime, replacing missing the missing information with 1900-1-1 or 00:00:00.

The return value is always a datetime.datetime object. If the value cannot be converted an exception is raised.

norman.validate.totime([fmt])

Return a validator which converts a string to a datetime.time.

If fmt is omitted, the ISO representation used by datetime.time.__str__ is used, otherwise it should be a format string for datetime.strptime.

If the value passed to the validator is a datetime.datetime, the time component is returned. If it is a datetime.time it is returned unchanged.

The return value is always a datetime.time object. If the value cannot be converted an exception is raised.