Skip to main content

Dolmen Layout/View Selector

Project description

The package dolmen.app.viewselector is an extension for Dolmen applications, allowing a basic management of alternative views.

About

In a CMS, it’s often very useful to be able to design and provide several views for a single item. These views can be relevant, according to a given context and situation. dolmen.app.viewselector allows you to define a view as being an “alternate” option to render a given context. A menu then provides you the machinery to select the most relevant view for your usecase.

A quick overview

To know that a component can provide alternative views, we need to explicitly specify it. An interface defines the “selector” capability:

>>> from dolmen.app.viewselector import IViewSelector
>>> list(IViewSelector)
['selected_view']

>>> IViewSelector['selected_view']
<...TextLine...>

The IViewSelector interface defines a single field, known as ‘selected_view’. The field value is merely the name of the Page component currently used:

>>> IViewSelector['selected_view'].default
u'base_view'

Out of the box, the default value is set to ‘base_view’.

Defining the content

To demonstrate the alternative views, we first need a context that is aware of the views selection:

>>> from zope.location import Location
>>> from zope.interface import implements

>>> class Bear(Location):
...  implements(IViewSelector)
...  selected_view = u"sleeping"

We defined the default view to the view named “sleeping”.

Defining alternate views

The alternative views are ‘pages’ (see megrok.layout and dolmen.app.layout) that are registered onto a dedicated menu. To define an alternative view, we inherit from the AlternativeView base class:

>>> import grokcore.view as grok
>>> from grokcore.component import testing
>>> from dolmen.app.viewselector import AlternativeView

>>> class Sleeping(AlternativeView):
...   grok.context(Bear)
...   grok.title("Sleeping bear")
...
...   def render(self):
...     return u"RRrrr..."

>>> testing.grok_component('sleeping', Sleeping)
True

The “sleeping” view that we defined as a default value for our IViewSelector is now defined and registered. Let’s register 2 other views, to populate the menu and provide a “realistic” usecase:

>>> class PolarFur(AlternativeView):
...   grok.context(Bear)
...   grok.title("Polar bear")
...
...   def render(self):
...     return u"I'm white !"

>>> testing.grok_component('polar', PolarFur)
True

>>> class SpringFur(AlternativeView):
...   grok.context(Bear)
...   grok.title("Spring bear")
...   grok.require("dolmen.content.Edit")
...
...   def render(self):
...     return u"I'm brown !"

>>> testing.grok_component('spring', SpringFur)
True

Default dynamic index

In order to render the selected view, another view is used. We may call it a “routing” view, as it’s used to lookup and render the desired component.

We first need to instance the two needed components, the content and the request

>>> from zope.publisher.browser import TestRequest

>>> herman = Bear()
>>> request = TestRequest()

The content provides IViewSelector, the interface for which the “routing” view is registered:

>>> IViewSelector.providedBy(herman)
True

The “routing” view is by convention called “index” and can be looked up as a basic view:

>>> from zope.component import getMultiAdapter
>>> index = getMultiAdapter((herman, request), name="index")
>>> index
<dolmen.app.viewselector.select.SelectedView...>

This view, when rendered, will look up and render the view named as the selected_view attribute, registered for the same content and request:

>>> herman.selected_view
u'sleeping'

>>> index.render()
u'RRrrr...'

If we set a different value for the selected_view attribute, the looked up view changes accordingly:

>>> herman.selected_view = u"polarfur"
>>> index.render()
u"I'm white !"

>>> herman.selected_view = u"springfur"
>>> index.render()
u"I'm brown !"

If the view doesn’t exist, a base message is returned:

>>> herman.selected_view = u"nothing"
>>> index.render()
u'The selected view is not a valid IPage component.'

Applying the view via the User interface

The selected view can be chosen from a list of available alternative view. This choice is made via a menu, for which the views are registered.

Apply

The menu above exposes the view ‘viewselector’, registered for a IViewSelector content. This view is the component that effectively changes the selected_view attribute to the clicked value.

Let’s simulate a click to test that view. The current value of the selected_view attribute is inconsistant:

>>> herman.selected_view
u'nothing'

We want it changed to something existing, like the PolarFur view:

>>> request = TestRequest(form={'name': u'polarfur'})
>>> handler = getMultiAdapter((herman, request), name="viewselector")
>>> handler
<dolmen.app.viewselector.select.ApplyView ...>

Logged in as an admin user, we can apply the selected view:

>>> login('zope.mgr', request)
>>> handler()
'http://127.0.0.1/herman'

The view redirects you to the base view of the content. The value is now changed:

>>> herman.selected_view
u'polarfur'

Changes

0.2.1 (2010-05-31)

  • Fixed the egg dist, by removing the zip-safe flag.

0.2 (2010-03-26)

  • Fixed missing MANIFEST.

0.1 (2010-03-25)

  • Initial release.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
dolmen.app.viewselector-0.2.1.tar.gz (8.8 kB) Copy SHA256 hash SHA256 Source None May 31, 2010

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page