Dexterity Types II: Growing Up

Get the code!

Get the code for this chapter (More info) using this command in the buildout directory:

cp -R src/ploneconf.site_sneak/chapters/09_dexterity_2_p5/ src/ploneconf.site

Las charlas existentes todavía faltan algunas funciones que queremos utilizar.

En esta parte vamos a:

  • add a marker interface to our talk type
  • create custom catalog indexes

  • consultar el catálogo para ellos

  • enable some more default features for our type

Add a marker interface to the talk type

Marcador de interfaces

The content type Talk is not yet a first class citizen because it does not implement its own interface. Interfaces are like nametags, telling other elements who and what you are and what you can do. A marker interface is like such a nametag. The talks actually have an auto-generated marker interface plone.dexterity.schema.generated.Plone_0_talk.

The problem is that the name of the Plone instance Plone is part of that interface name. If you now moved these types to a site with another name, code that uses these Interfaces would no longer find the objects in question.

To solve this we add a new Interface to interfaces.py:

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# -*- coding: utf-8 -*-
"""Module where all interfaces, events and exceptions live."""

from zope.publisher.interfaces.browser import IDefaultBrowserLayer
from zope.interface import Interface


class IPloneconfSiteLayer(IDefaultBrowserLayer):
    """Marker interface that defines a browser layer."""


class ITalk(Interface):
    """Marker interface for Talks
    """

ITalk is a marker interface. We can bind Views and Viewlets to content that provide these interfaces. Lets see how we can provide this Interface. There are two solution for this.

  1. dejemosla ser instancias de una clase que implementa esta interfaz

  2. Registra esta interfaz como un comportamiento y habilitalo en su llamadas.

The first option has an important drawback: Only new talks would be instances of the new class. We would either have to migrate the existing talks or delete them.

So let’s register the interface as a behavior in behaviors/configure.zcml

<plone:behavior
  title="Talk"
  description="Marker interface for talks to be able to bind views to."
  provides="..interfaces.ITalk"
  />

And enable it on the type in profiles/default/types/talk.xml

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<property name="behaviors">
 <element value="plone.app.dexterity.behaviors.metadata.IDublinCore"/>
 <element value="plone.app.content.interfaces.INameFromTitle"/>
 <element value="ploneconf.site.behaviors.social.ISocial"/>
 <element value="ploneconf.site.interfaces.ITalk"/>
</property>

Either reinstall the addon, apply the behavior by hand or run an upgrade step (see below) and the interface will be there.

Then we can safely bind the talkview to the new marker interface.

<browser:page
  name="talkview"
  for="ploneconf.site.interfaces.ITalk"
  layer="zope.interface.Interface"
  class=".views.TalkView"
  template="templates/talkview.pt"
  permission="zope2.View"
  />

Now the /talkview can only be used on objects that implement said interface. We can now also query the catalog for objects providing this interface catalog(object_provides="ploneconf.site.interfaces.ITalk"). The talklistview and the demoview do not get this constraint since they are not only used on talks.

Nota

Just for completeness sake, this is what would have to happen for the first option:

  • Create a new class that inherits from plone.dexterity.content.Container and implements the marker interface.

    from plone.dexterity.content import Container
from ploneconf.site.interfaces import ITalk
from zope.interface import implements

class Talk(Container):
    implements(ITalk)

  • Modify the class for new talks in profiles/default/types/talk.xml

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    ...
<property name="add_permission">cmf.AddPortalContent</property>
<property name="klass">ploneconf.site.content.talk.Talk</property>
<property name="behaviors">
...

  • Create an upgrade step that changes the class of the existing talks. A reuseable method to do such a thing is in is plone.app.contenttypes.migration.dxmigration.migrate_base_class_to_new_class.

Upgrade steps

When projects evolve you’ll sometimes have to modify various things while the site is already up and brimming with content and users. Upgrade steps are pieces of code that run when upgrading from one version of an addon to a newer one. They can do just about anything.

We will create an upgrade step that

  • runs the typeinfo step (i.e. loads the GenericSetup configuration stores in profiles/default/types.xml and profiles/default/types/... so we don’t have to reinstall the addon to have our changes from above take effect) and
  • cleans up some content that might be scattered around the site in the early stages of creating it. We will move all talks to a folder talks (unless they already are there).

Upgrade steps are usually registered in their own zcml file. Create upgrades.zcml

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<configure
  xmlns="http://namespaces.zope.org/zope"
  xmlns:i18n="http://namespaces.zope.org/i18n"
  xmlns:genericsetup="http://namespaces.zope.org/genericsetup"
  i18n_domain="ploneconf.site">

  <genericsetup:upgradeStep
    title="Update and cleanup talks"
    description="Updates typeinfo and moves talks to a folder 'talks'"
    source="1000"
    destination="1001"
    handler="ploneconf.site.upgrades.upgrade_site"
    sortkey="1"
    profile="ploneconf.site:default"
    />

</configure>

The upgrade step bumps the version number of the GenericSetup profile of ploneconf.site from 1 to 1001. The version is stored in profiles/default/metadata.xml. Change it to

<version>1001</version>

Include the new upgrades.zcml in our configure.zcml by adding:

<include file="upgrades.zcml" />

GenericSetup now expects the code as a method upgrade_site in the file upgrades.py. Let’s create it.

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from plone import api
import logging

default_profile = 'profile-ploneconf.site:default'
logger = logging.getLogger(__name__)


def upgrade_site(setup):
    setup.runImportStepFromProfile(default_profile, 'typeinfo')
    catalog = api.portal.get_tool('portal_catalog')
    portal = api.portal.get()
    # Create a folder 'The event' if needed
    if 'the-event' not in portal:
        theevent = api.content.create(
            container=portal,
            type='Folder',
            id='the-event',
            title='The event')
    else:
        theevent = portal['the-event']

    # Create folder 'Talks' inside 'The event' if needed
    if 'talks' not in theevent:
        talks = api.content.create(
            container=theevent,
            type='Folder',
            id='talks',
            title='Talks')
    else:
        talks = theevent['talks']
    talks_url = talks.absolute_url()

    # Get all talks
    brains = catalog(portal_type='talk')
    for brain in brains:
        if talks_url in brain.getURL():
            # Skip if the talk is already in target-folder
            continue
        obj = brain.getObject()
        logger.info('Moving %s to %s' % (obj.absolute_url(), talks.absolute_url()))
        # Move each talk to the folder '/the-event/talks'
        api.content.move(
            source=obj,
            target=talks,
            safe_id=True)

After restarting the site we can run the step:

On the console you should see logging messages like:

INFO ploneconf.site Moving http://localhost:8080/Plone/old-talk1 to http://localhost:8080/Plone/the-event/talks

Alternatively you can select which upgrade steps to run like this:

  • In the ZMI got to portal_setup
  • Go to the tab Upgrades
  • Select ploneconf.site from the dropdown and click Choose profile
  • Run the upgrade step.

Ver también

http://docs.plone.org/develop/addons/components/genericsetup.html#id1

Nota

Upgrading from an older version of Plone to a newer one also runs upgrade steps from the package plone.app.upgrade. You should be able to upgrade a clean site from 2.5 to 5.0a2 with a click.

For an example see the upgrade-step to Plone 5.0a1 https://github.com/plone/plone.app.upgrade/blob/master/plone/app/upgrade/v50/alphas.py#L23

Add a browserlayer

A browserlayer is another such marker interface. Browserlayers allow us to easily enable and disable views and other site functionality based on installed add-ons and themes.

Since we want the features we write only to be available when ploneconf.site actually is installed we can bind them to a browserlayer.

Our package already has a browserlayer (bobtemplates.plone added it). See interfaces.py:

from zope.publisher.interfaces.browser import IDefaultBrowserLayer

class IPloneconfSiteLayer(IDefaultBrowserLayer):
    """Marker interface that defines a browser layer."""

Is is enabled by GenericSetup when installing the package since it is registered in profiles/default/browserlayer.xml

<?xml version="1.0"?>
<layers>
  <layer
    name="ploneconf.site"
    interface="ploneconf.site.interfaces.IPloneconfSiteLayer"
  />
</layers>

We should bind all views to it. Here is an example using the talkview.

<browser:page
  name="talklistview"
  for="*"
  layer="..interfaces.IPloneconfSiteLayer"
  class=".views.TalkListView"
  template="templates/talklistview.pt"
  permission="zope2.View"
  />

Note the relative python path ..interfaces.IPloneconfSiteLayer. It is equivalent to the absolute path ploneconf.site.interfaces.IPloneconfSiteLayer.

Ver también

http://docs.plone.org/develop/plone/views/layers.html

Exercise

Do you need to bind the Social viewlet from chapter 22 to this new browser layer?

Solution

No, it would make no difference since the viewlet is already bound to the marker interface ploneconf.site.behaviors.social.ISocial.

Add catalog indexes

In the talklistview we had to wake up all objects to access some of their attributes. That is ok if we don’t have many objects and they are light dexterity objects. If we had thousands of objects this might not be a good idea.

Instead of loading them all into memory we will use catalog indexes to get the data we want to display.

Add a new file profiles/default/catalog.xml

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<?xml version="1.0"?>
<object name="portal_catalog">
  <index name="type_of_talk" meta_type="FieldIndex">
    <indexed_attr value="type_of_talk"/>
  </index>
  <index name="speaker" meta_type="FieldIndex">
    <indexed_attr value="speaker"/>
  </index>
  <index name="audience" meta_type="KeywordIndex">
    <indexed_attr value="audience"/>
  </index>

  <column value="audience" />
  <column value="type_of_talk" />
  <column value="speaker" />
</object>

This adds new indexes for the three fields we want to show in the listing. Not that audience is a KeywordIndex because the field is multi-valued, but we want a separate index entry for every value in an object.

The column .. entry allows us to display the values of these indexes in the tableview of collections.

Nota

Until Plone 4.3.2 adding indexes in catalog.xml was harmful because reinstalling the addon purged the indexes! See http://www.starzel.de/blog/a-reminder-about-catalog-indexes.

Ver también

http://docs.plone.org/develop/plone/searching_and_indexing/indexing.html

Query for custom indexes

The new indexes behave like the ones that Plone has already built in:

>>> (Pdb) from Products.CMFCore.utils import getToolByName
>>> (Pdb) catalog = getToolByName(self.context, 'portal_catalog')
>>> (Pdb) catalog(type_of_talk='Keynote')
[<Products.ZCatalog.Catalog.mybrains object at 0x10737b9a8>, <Products.ZCatalog.Catalog.mybrains object at 0x10737b9a8>]
>>> (Pdb) catalog(audience=('Advanced', 'Professionals'))
[<Products.ZCatalog.Catalog.mybrains object at 0x10737b870>, <Products.ZCatalog.Catalog.mybrains object at 0x10737b940>, <Products.ZCatalog.Catalog.mybrains object at 0x10737b9a8>]
>>> (Pdb) brain = catalog(type_of_talk='Keynote')[0]
>>> (Pdb) brain.speaker
u'David Glick'

We now can use the new indexes to improve the talklistview so we don’t have to wake up the objects any more. Instead we use the brains new attributes.

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class TalkListView(BrowserView):
    """ A list of talks
    """

    def talks(self):
        results = []
        portal_catalog = api.portal.get_tool('portal_catalog')
        current_path = "/".join(self.context.getPhysicalPath())

        brains = portal_catalog(portal_type="talk",
                                path=current_path)
        for brain in brains:
            results.append({
                'title': brain.Title,
                'description': brain.Description,
                'url': brain.getURL(),
                'audience': ', '.join(brain.audience or []),
                'type_of_talk': brain.type_of_talk,
                'speaker': brain.speaker,
                'uuid': brain.UID,
                })
        return results

The template does not need to be changed and the result in the browser did not change, either.

Add collection criteria

To be able to search content in collections using these new indexes we would have to register them as criteria for the querystring widget that collections use. As with all features make sure you only do this if you really need it!

Add a new file profiles/default/registry.xml

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<registry>
  <records interface="plone.app.querystring.interfaces.IQueryField"
           prefix="plone.app.querystring.field.audience">
    <value key="title">Audience</value>
    <value key="description">A custom speaker index</value>
    <value key="enabled">True</value>
    <value key="sortable">False</value>
    <value key="operations">
      <element>plone.app.querystring.operation.string.is</element>
    </value>
    <value key="group">Metadata</value>
  </records>
  <records interface="plone.app.querystring.interfaces.IQueryField"
           prefix="plone.app.querystring.field.type_of_talk">
    <value key="title">Type of Talk</value>
    <value key="description">A custom index</value>
    <value key="enabled">True</value>
    <value key="sortable">False</value>
    <value key="operations">
      <element>plone.app.querystring.operation.string.is</element>
    </value>
    <value key="group">Metadata</value>
  </records>
  <records interface="plone.app.querystring.interfaces.IQueryField"
           prefix="plone.app.querystring.field.speaker">
    <value key="title">Speaker</value>
    <value key="description">A custom index</value>
    <value key="enabled">True</value>
    <value key="sortable">False</value>
    <value key="operations">
      <element>plone.app.querystring.operation.string.is</element>
    </value>
    <value key="group">Metadata</value>
  </records>
</registry>

Ver también

http://docs.plone.org/develop/plone/functionality/collections.html#add-new-collection-criteria-new-style-plone-app-collection-installed

Add versioning through GenericSetup

Configure the versioning policy and a diff-view for talks through GenericSetup.

Add new file profiles/default/repositorytool.xml

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<?xml version="1.0"?>
<repositorytool>
  <policymap>
    <type name="talk">
      <policy name="at_edit_autoversion"/>
      <policy name="version_on_revert"/>
    </type>
  </policymap>
</repositorytool>

Add new file profiles/default/diff_tool.xml

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<?xml version="1.0"?>
<object>
  <difftypes>
    <type portal_type="talk">
      <field name="any" difftype="Compound Diff for Dexterity types"/>
    </type>
  </difftypes>
</object>

Finally you need to activate the versioning behavior on the content type. Edit profiles/default/types/talk.xml:

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<property name="behaviors">
 <element value="plone.app.dexterity.behaviors.metadata.IDublinCore"/>
 <element value="plone.app.content.interfaces.INameFromTitle"/>
 <element value="ploneconf.site.behaviors.social.ISocial"/>
 <element value="ploneconf.site.interfaces.ITalk"/>
 <element value="plone.app.versioningbehavior.behaviors.IVersionable" />
</property>