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Apply a marker interface to a request to code for special presentation of a subsection.

Project description

Section Sub Skin

Section Sub Skin is a system for applying an interface to a request that maps
into a description of how a theme should change for a subsection of the site.
These mappings do not automatically change things about the theme, but they
are available in Zope3 style browser views for conditional inclusion.

The recommended way of doing this currently (as DTML views are not supported)
is to create a view that uses TAL rather than the standard DTML method of
generating customised CSS files.

Browser views that inherit from `collective.sectionsubskin.browser.subskin.SubSkin`
have a "subskin" variable set which is accessible from the view.

For example, if all subskins contain a `colour` attribute, the current colour can be found with::

<tal:colour replace="view/subskin/colour" on-error="string:MyDefaultColour"/>

Boring imports and setup (move to You probably want to ignore all this.::

>>> from import ztapi
>>> import zope.interface
>>> from AccessControl.SecurityManagement import newSecurityManager
>>> from AccessControl.User import UnrestrictedUser
>>> from Testing.makerequest import makerequest
>>> app = makerequest(app)
>>> portal = portal.__of__(app)
>>> newSecurityManager(None, UnrestrictedUser('god', '', ['Manager'], ''))
>>> from Products.Five.testbrowser import Browser
>>> browser = Browser()
>>> from Testing.ZopeTestCase import user_password
>>> browser.addHeader('Authorization', 'Basic %s:%s' % ('portal_owner', user_password)) # Only needed as our view is a dummy, if registered through ZCML we'd use permission=zope2.View

Creating a new theme definition is very easy::

>>> from collective.sectionsubskin.definition import BaseDefinition
>>> from collective.sectionsubskin.interfaces import ISubskinDefinition
>>> from collective.sectionsubskin.test_support import IRedSkin, RedSkin

Again, on the filesystem, the value of this code is::

class IRedSkin(ISubskinDefinition):

class RedSkin(BaseDefinition):
title = u"RedSkin"
colour = u"FF0000"
type_interface = IRedSkin

We can keep an instance of this in a list so we can poke it later::

>>> skins = []
>>> skins.append(RedSkin())
>>> skins
[<SectionSubSkin named RedSkin>]
>>> skins[0].colour

These are just basic python objects that inherit from BaseDefinition, which
conditionally inherits from p4a.subtyper as well as providing some helper methods.
This means you can do anything with them that you can with normal objects::

>>> from collective.sectionsubskin.test_support import IBlueSkin, BlueSkin
>>> skins.append(BlueSkin())

Again, on the filesystem, the value of this code is::

class IBlueSkin(ISubskinDefinition):

class BlueSkin(BaseDefinition):
title = u"BlueSkin"
colour = u"0000FF"
type_interface = IBlueSkin

The skins variable now contains both skins::

>>> skins
[<SectionSubSkin named RedSkin>, <SectionSubSkin named BlueSkin>]
>>> skins[1].colour

Now, if we create a browser view for the site (registed in test_support)::

>>> from collective.sectionsubskin.test_support import colours

These things need to be in filesystem code so Zope doesn't throw a paddy, so it's actually::

from collective.sectionsubskin.browser.subskin import SubSkin
class colours(SubSkin):
""" Colours. """

def render(self):
""" Render the CSS. """
return """html { background-color: #%s; }""" % (self.subskin.colour)
return """"""

__call__ = render

def __of__(self, parent):
# We don't care about acquisition for this toy example
return self

We can instantiate one directly, traverse to it or visit it in a browser::

>>> colours(portal, app.REQUEST).render()
>>> portal.unrestrictedTraverse("colours.css").render()
>>>"%s/colours.css" % self.portal.absolute_url())
>>> browser.contents

Only the last of these will trigger the subskin, as it only activates on HTTP requests traversing over the object.

As there is no subskin active for the root it correctly renders an empty string.
If, however, we create some subfolders we can assign them subskins::

>>> red = portal[portal.invokeFactory("Folder","red")]
>>> zope.interface.alsoProvides(red, (IRedSkin, ))
>>> blue = portal[portal.invokeFactory("Folder","blue")]
>>> zope.interface.alsoProvides(blue, (IBlueSkin, ))
>>> noskin = portal[portal.invokeFactory("Folder","noskin")]

Now when we traverse to the red folder we see the red skin::

>>>"%s/red/colours.css" % self.portal.absolute_url())
>>> browser.contents
'html { background-color: #FF0000; }'

But if we go blue we see the other option::

>>>"%s/blue/colours.css" % self.portal.absolute_url())
>>> browser.contents
'html { background-color: #0000FF; }'

Any unmarked folders still show no subskin::

>>>"%s/noskin/colours.css" % self.portal.absolute_url())
>>> browser.contents

Weird traversal will give the last skin encountered::

>>>"%s/red/blue/colours.css" % self.portal.absolute_url())
>>> browser.contents
'html { background-color: #0000FF; }'


>>>"%s/blue/red/colours.css" % self.portal.absolute_url())
>>> browser.contents
'html { background-color: #FF0000; }'


Added support to the traverser to remove an existing subskin when a new definition is traversed over
Matthew Wilkes


Works in 2.10 well. 2.9 with Five 1.4.4 works but is unsupported.

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