Basic usage

To use this feature, you should:

• declare plone.browserlayer as a dependency, e.g. in setup.py:

  install_requires=[
        'plone.browserlayer',
    ],
  

• ensure that its ZCML is loaded, e.g. with an include from your own package:

  <include package="plone.browserlayer" />
  

• create a layer marker interface unique to your product:

  from zope.interface import Interface
  class IMyProductLayer(Interface):
      """A layer specific to my product
      """
  

• register this with GenericSetup, in a browserlayer.xml file:

  <layers>
      <layer name="my.product"
             interface="my.product.interfaces.IMyProductLayer" />
  </layers>
  

• register visual components in ZCML for this layer, e.g.:

  <browser:page
      name="my-view"
      for="*"
      layer=".interfaces.IMyProductLayer"
      permission="zope.Public"
      template="my-view.pt"
      />
  

No seriously, it works, just look here

In testing.zcml we have registered a view, layer-test-view, available only for the layer plone.browserlayer.tests.interfaces.IMyProductLayer.

Before the product is installed, we cannot view this:

>>> from plone.browserlayer.tests.interfaces import IMyProductLayer
>>> from plone.browserlayer import utils
>>> IMyProductLayer in utils.registered_layers()
False

>>> from Products.Five.testbrowser import Browser
>>> browser = Browser()
>>> browser.open(self.portal.absolute_url() + '/@@layer-test-view')
Traceback (most recent call last):
...
HTTPError: HTTP Error 404: Not Found

We can view a view registered for the default layer, though:

>>> browser.open(self.portal.absolute_url() + '/@@standard-test-view')
>>> print browser.contents
A standard view

However, if we install the product the interface is registered in the local site manager. Here we use the utility method directly, though we could also use GenericSetup.

>>> utils.register_layer(IMyProductLayer, name='my.product')
>>> IMyProductLayer in utils.registered_layers()
True

And if we now traverse over the site root and render the view, it should be there.

>>> browser.open(self.portal.absolute_url() + '/@@layer-test-view')
>>> print browser.contents
A local view

Unlike when applying a new skin, layers installed in this way do not override views registered for the default layer.

>>> browser.open(self.portal.absolute_url() + '/@@standard-test-view')
>>> print browser.contents
A standard view

It is also possible to uninstall a layer:

>>> IMyProductLayer in utils.registered_layers()
True
>>> utils.unregister_layer(name='my.product')
>>> IMyProductLayer in utils.registered_layers()
False

>>> browser.open(self.portal.absolute_url() + '/@@layer-test-view')
Traceback (most recent call last):
...
HTTPError: HTTP Error 404: Not Found

GenericSetup support

Most of the time, you will be registering layers using GenericSetup. Here is how that looks.

>>> from Products.CMFCore.utils import getToolByName
>>> portal_setup = getToolByName(self.portal, 'portal_setup')

We should be able to install our product's profile. For the purposes of this test, the profile is defined in tests/profiles/default/testing and registered in testing.zcml. It has a file called browserlayer.xml which contains:

<layers>
    <layer name="plone.browserlayer.tests"
           interface="plone.browserlayer.tests.interfaces.IMyProductLayer" />
</layers>

Let's import it:

>>> IMyProductLayer in utils.registered_layers()
False
>>> _ = portal_setup.runAllImportStepsFromProfile('profile-plone.browserlayer:testing')
>>> IMyProductLayer in utils.registered_layers()
True

And just to prove that everything still works:

>>> browser.open(self.portal.absolute_url() + '/@@layer-test-view')
>>> print browser.contents
A local view

>>> browser.open(self.portal.absolute_url() + '/@@standard-test-view')
>>> print browser.contents
A standard view

1.0.1 - 2009-09-09

• Be more robust against broken layer registrations. These can occur when packages with registered layers are removed. [wichert]
• Clarified license and copyright. [hannosch]
• Register ourselves for the more generic ISiteRoot from CMFCore and not IPloneSiteRoot. [hannosch]
• Declare test dependencies in an extra. [hannosch]
• Specify package dependencies. [hannosch]

1.0.0 - 2008-04-20

• Unchanged from 1.0rc4

1.0rc4

• Register the GenericSetup import and export steps using zcml. This means you will no longer need to install this package manually. [wichert]

1.0rc3

• Include README.txt and HISTORY.txt in the package's long description. [wichert]
• Add metadata.xml to the GenericSetup profile. This fixes a deprecation warning for Plone 3.1 and later. [wichert]

1.0b1

• Initial package structure. [zopeskel]