= Noneable widgets =

In the spirit of Postel's Law, the Noneable widgets permits users to enter
just whitespace, while ensuring that the schema's field value is None.


== Noneable TextLine widget ==

This custom widget is used to normalise the value of meaning less
text value to None.

    >>> from lp.app.widgets.textwidgets import NoneableTextWidget

The IMilestone code_name field cannot be an empty string or a string
composed of whitespace; the value is considered to be None.

    >>> from canonical.launchpad.webapp.servers import LaunchpadTestRequest
    >>> from lp.registry.interfaces.milestone import IMilestone

    >>> field = IMilestone['code_name']
    >>> request = LaunchpadTestRequest(
    ...     form={'field.code_name' : ' '})
    >>> widget = NoneableTextWidget(field, request)

The widget converted the meaningless value to None.

    >>> print widget.getInputValue()
    None

Excess whitespace and newlines are stripped.

    >>> request = LaunchpadTestRequest(
    ...     form={'field.code_name' : ' flower \n'})
    >>> widget = NoneableTextWidget(field, request)
    >>> print widget.getInputValue()
    flower


== Noneable Description widget ==

This custom widget is used to normalise the value of meaning less
text value to None.

    >>> from lp.app.widgets.textwidgets import (
    ...     NoneableDescriptionWidget)

The IMilestone description field cannot be an empty string or a string
composed of whitespace; the value is considered to be None.

    >>> field = IMilestone['summary']
    >>> request = LaunchpadTestRequest(
    ...     form={'field.summary' : ' '})
    >>> widget = NoneableDescriptionWidget(field, request)

The widget converted the meaningless value to None.

    >>> print widget.getInputValue()
    None

Excess whitespace is stripped, but newlines are preserved.

    >>> request = LaunchpadTestRequest(
    ...     form={'field.summary' : ' flower \n grass '})
    >>> widget = NoneableDescriptionWidget(field, request)
    >>> widget.getInputValue()
    u'flower \n grass'