Building Content Types
with Dexterity
David Glick
Plone Conference 2009

Groundwire uses the power of technology
to connect people, organizations, and communities
working to build a sustainable society.

What is a content type?

A way of categorizing
the items in your site
Page Something Else

Schema

Workflow

Custom view templates

Miscellaneous settings
• Placeful restrictions
• Comments
• Searchability
• Per-type portlet assignments
• etc.

History Lesson
http://commons.wikimedia.org/wiki/File:1893_Nina_Pinta_Santa_Maria_replicas.jpg

Content Management
Framework (CMF)
• Underlying framework for registering
types, assigning workflow
• CMFDefault contains sample types which
used to be used by Plone
• Not schema-based

Archetypes
• Schema-based form generation
• Basis of Plone's current default content
types (ATContentTypes)
• Not going away anytime soon

Dexterity
Martin Aspeli

Goals
http://www.fickr.com/photos/paul-w-locke/1662634481/sizes/m/

Make filesystem content type
development sane

Make through-the-web content
type development sane

Make it possible to switch
back and forth between the 2

Philosophy
http://www.fickr.com/photos/ulrichsson/3519217737/

Reuse over reinvention

Small over big
Pro duc ts .Arc he ty pe s
plone.app.dexterity
base classes
metadata plone.behavior
felds schema plone.directives.*
plone.autoform
widgets
plo ne .de x te rity
storage
plone.supermodel z3c.form
reference
engine
plone.schemaeditor
plone.app.relations

Natural interaction over
excessive generality
diffculty
time

Real code over generated
code

Zope 3 over Zope 2

Automated testing over
wishful thinking

Let's build a content type!

Installing Dexterity
[buildout]
extends =
http://dist.plone.org/release/3.3.1/versions.cfg
http://good-py.appspot.com/release/dexterity/1.0a2
…
[instance]
…
eggs =
…
plone.app.dexterity

Installing Dexterity

Dexterity Types Control Panel

Adding a Type

Adding a Type

Adding a 'Plonista' instance

Adding a 'Plonista' instance

The default 'Plonista' view

A few issues
• Bad short name for URL (“plonista”)
• Showing lots of metadata fields we don't
care about
• We want it to say “Name” instead of “Title”
• Doesn't store anything interesting yet :)
...so let's fix it!

Behaviors
s ubc la s s ing s c he m a be ha v io rs
schema e x te ns io n
ATFile schema
model
schema
schema
schema Deco thumbnail
schema
layout image
ATFile
Dexterity
versioned File name from
CustomATFile ATFile title
geolocatable
ratings

Editing the 'Plonista' Behaviors
Disable this to hide the metadata
Enable this to generate short
name from title

Adding a Field

Adding a Field
This will replace the title
feld that used to come
from the Dublin Core
behavior.

Adding a Field

Editing a field We are changing the title
of this feld to 'Name'.

Edit a revised 'Plonista'

Rapid Prototyping
• The schema object in memory is directly
modified, so changes take effect
immediately.
• The changes are also serialized to XML and
stored in the ZODB (in a property of the
FTI), so they are persistent when Zope
restarts.

Modifying a Type
• You can add, remove, and rename fields
through the web.
• But, values stored in existing instances will
not be automatically removed or converted.
So be careful.

Some more desired refinements
• Custom add permission
• Show the 'bio' field in a separate fieldset.
…we can't do these through the web
(at least not yet)

Filesystem roundtripping
We b File s y s te m
Zope 3 Schema Schema as
Python interface
Content
Editing py
Schema
Editing
xml xml External
GenericSetup tools
import/export
XML schema in XML schema
FTI on flesystem

Exporting a type
• GenericSetup export for now;
better UI coming :)

Minimal Dexterity package structure
• example.ploneconf09
» /example
• /ploneconf09
• /__init__.py
• /configure.zcml
• /profiles
• /default
• /metadata.xml
• /types.xml
• /types
• plonista.xml
» /setup.py

setup.py
setup(name='example.ploneconf09',
...
install_requires=[
'setuptools',
'plone.app.dexterity', Make sure we automatically get Dexterity
# -*- Extra requirements: -*-
],
entry_points="""
[z3c.autoinclude.plugin]
Make sure we don't need a ZCML slug
target = plone (in Plone 3.3 and greater)
""",
)

__init__.py
# Nothing to see here; move along. :)

configure.zcml
<configure
xmlns="http://namespaces.zope.org/zope"
xmlns:grok="http://namespaces.zope.org/grok"
xmlns:genericsetup="http://namespaces.zope.org/genericsetup"
i18n_domain="example.ploneconf09">
Loads ZCML for all dependency
<includeDependencies package="."/> packages listed in setup.py
<genericsetup:registerProfile
name="default"
title="Plone conference Dexterity example"
directory="profiles/default"
description="Installs the Dexterity example for the Plone conference."
provides="Products.GenericSetup.interfaces.EXTENSION"
/>
</configure>

types.xml
<?xml version="1.0"?>
<object name="portal_types" meta_type="Plone Types Tool">
<object name="plonista" meta_type="Dexterity FTI"/>
</object>
metadata.xml
<metadata>
<version>1</version>
<dependencies>
<dependency>profile-plone.app.dexterity:default</dependency>
</dependencies>
</metadata>

plonista.xml
<?xml version="1.0"?>
<object name="plonista" meta_type="Dexterity FTI"
xmlns:i18n="http://xml.zope.org/namespaces/i18n">
<property name="title">Plonista</property>
<property name="description">A member of the Plone community.</property>
<property name="content_icon">document_icon.png</property>
<property name="icon_expr">string:${portal_url}/document_icon.png</property>
<property name="factory">plonista</property>
<property name="link_target"></property>
<property name="immediate_view">view</property>
<property name="global_allow">True</property>
<property name="filter_content_types">True</property>
<property name="allowed_content_types"/>
<property name="allow_discussion">False</property>
<property name="default_view">view</property>
<property name="view_methods">
<element value="view"/>
</property>
<property name="default_view_fallback">False</property>

plonista.xml (continued)
<property name="add_permission">cmf.AddPortalContent</property>
<property name="klass">plone.dexterity.content.Item</property>
<property name="behaviors">
<element value="plone.app.content.interfaces.INameFromTitle"/>
</property>
<property name="schema"></property> Can put model in a Zope 3 schema.
<property
name="model_source">&lt;model xmlns="http://namespaces.plone.org/supermodel/schema"&gt;
&lt;schema&gt;
&lt;field name="title" type="zope.schema.TextLine"&gt;
&lt;description /&gt;
&lt;title&gt;Name&lt;/title&gt;
&lt;/field&gt;
&lt;field name="portrait" type="plone.namedfile.field.NamedBlobImage"&gt;
&lt;title&gt;Portrait&lt;/title&gt;
&lt;/field&gt;
&lt;field name="bio" type="plone.app.textfield.RichText"&gt;
&lt;title&gt;Bio&lt;/title&gt;
&lt;/field&gt;
&lt;/schema&gt;
&lt;/model&gt;</property>
<property name="model_file"></property> Can put model in a separate fle.
(These are the Dexterity-specifc bits.)

plonista.xml (continued)
<alias from="(Default)" to="(selected layout)"/>
<alias from="edit" to="@@edit"/>
<alias from="sharing" to="@@sharing"/>
<alias from="view" to="@@view"/>
<action title="View" action_id="view" category="object" condition_expr=""
icon_expr="" link_target="" url_expr="string:${object_url}"
visible="True">
<permission value="View"/>
</action>
<action title="Edit" action_id="edit" category="object" condition_expr=""
icon_expr="" link_target="" url_expr="string:${object_url}/edit"
visible="True">
<permission value="Modify portal content"/>
</action>
</object>

Custom add permission
• In configure.zcml:
<permission
id="example.ploneconf09.AddPlonista"
title="example.ploneconf09: Add plonista"
/>
• In plonista.xml:
<property name="add_permission">example.ploneconf09.AddPlonista</property>
• Add collective.autopermission dependency
in setup.py, rerun buildout

Using a Zope 3 schema
• In plonista.py:
from zope import schema
from plone.directives import form
from plone.namedfile.field import NamedBlobImage
from plone.app.textfield import RichText
class IPlonista(form.Schema):
title = schema.TextLine(
title = u'Name',
)
portrait = NamedBlobImage(
title = u'Portrait',
required = False,
)
bio = RichText(
title=u'Bio',
required = False,
)

Using a Zope 3 Schema
• In configure.zcml:
<configure
...
xmlns:grok="http://namespaces.zope.org/grok">
<grok:grok package="."/>
...
</configure>
• Add five.grok to dependencies in setup.py
• In plonista.xml:
<property name="schema">example.ploneconf09.plonista.IPlonista</property>
<property name="model_source"></property>

Specifying a fieldset
class IPlonista(form.Schema):
…
bio = RichText(
title=u'Bio',
required = False,
)
form.fieldset(
'bio',
label=u'Bio',
fields=['bio'],
)

More form directives
• widget – specify alternate widget
• omitted – omits fields
• mode – input, display, or hidden
• order_before, order_after – adjust position

plone.directives.dexterity
• read_permission
• write_permission

Custom view template
• In plonista.py:
from five import grok
class View(grok.View):
grok.context(IPlonista)
grok.require('zope2.View')

• In plonista_templates/view.pt
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"
xmlns:tal="http://xml.zope.org/namespaces/tal"
xmlns:metal="http://xml.zope.org/namespaces/metal"
xmlns:i18n="http://xml.zope.org/namespaces/i18n"
lang="en" metal:use-macro="context/main_template/macros/master"
i18n:domain="example.conference">
<body>
<metal:main fill-slot="main">
<tal:main-macro metal:define-macro="main">
<div tal:replace="structure provider:plone.abovecontenttitle" />
<h1 class="documentFirstHeading" tal:content="context/title" />
<div tal:replace="structure provider:plone.belowcontenttitle" />
<div tal:replace="structure provider:plone.abovecontentbody" />
<div tal:define="portrait nocall:context/portrait" tal:condition="nocall:portrait"><img
tal:attributes="src string:${context/absolute_url}/@@download/portrait/${portrait/filename};
height portrait/_height | nothing;
width portrait/_width | nothing;" />
</div>
<div tal:content="structure context/bio/output" />
<div tal:replace="structure provider:plone.belowcontentbody" />
</tal:main-macro>
</metal:main>
</body>
</html>

Add the package to buildout
[buildout]
develop = src/example.ploneconf09
[instance]
…
eggs =
…
example.ploneconf09

Install the new package

Existing content automatically
provides the new schema

The custom view

The pieces
http://www.fickr.com/photos/intvgene/370973576/

five.grok
• Allows for writing configuration directives
in Python and in place, instead of using
ZCML.
• “Grok” a package using the following
ZCML, and it will register anything its
grokkers find and recognize.
<grok:grok package="." />

plone.dexterity
• Base content classes.
• FTI (Factory Type Information)
provides for dynamic lookup
of model and schema.
• Default edit form and view.

plone.autoform
• Dexterity renders widgets using z3c.form.
• Plone.autoform makes it possible for a form
to be composed by schemas and form hints
from different sources.
(Main schema + behavior schemas,
in the case of Dexterity.)

plone.schemaeditor
• Provides the UI for editing Zope 3
interfaces through the web.
• Dexterity integrates it with the Dexterity
types control panel, but it could be used
separately.
• IFieldFactory lookup determines what
fields can be edited.

plone.supermodel
• Serializer translates a Zope 3 schema into
XML.
• Parser translates an XML schema into a
Zope 3 schema.
• Easily extensible
» Field handlers found via adapter lookup
» Additional metadata handlers may handle
custom XML namespaces

plone.directives.form
• Defines the form rendering hint directives
that may be included in schemas for use by
plone.autoform when rendering forms and
views.

plone.directives.dexterity
• Grok directives for custom content classes
and forms.

plone.folder
• Orderable Btree-based folder
implementation.
• Will also be the basis for AT-based folders
in Plone 4.

plone.behavior
• A behavior is a conditional adapter.
• In Dexterity, the condition is whether the
behavior is listed in the FTI for an item.
• ZCML directive for registering new
behaviors.

plone.rfc822
• Supports the marshalling of Dexterity
content into RFC 822 format.
• Used to support access via WebDAV.

plone.app.dexterity
• Pulls in everything you need.
• Standard behaviors.
» Dublin Core
» Related Items
• Dexterity types control panel.

Status report / roadmap
http://www.fickr.com/photos/brianatwebbmoto/2392041992/sizes/m/

Core functionality

Schema serialization

Automatic form
generation

Portlet assignments

Content rules

Relations
• Not working between Archetypes and
Dexterity content in the same site

Widgets
• Not as rich as Archetypes yet, but better
than formlib. We have autocomplete,
browse-for-content, file/image upload.

TTW schema editing
• Works fine, but needs more real-life use.

Image & file support
(via plone.namedfile &
plone.formwidget.namedfile)
• No support for image scaling yet.

Text transform support
(via plone.app.textfield)

Select field support
• No way to define vocabularies through the
web yet.

WebDAV support

Versioning & staging
• In progress

TTW behavior creation

Automatic migration
from Archetypes
content

Multi-lingual content
• Some discussion, but no code yet.

Link integrity checks

Upcoming releases
• Second alpha release was on Oct. 12
• First beta release coming soon

Compatibility
• Plone 3
• Plone 4 compatibility coming soon

Performance

Further information
• Dexterity manual:
http://plone.org/products/dexterity/docu
mentation/manual/developer-manual
• Behaviors manual:
http://plone.org/products/dexterity/docu
mentation/manual/behaviors
• Over 30,000 words!

Example Code
• example.dexterity
• example.conference
(both in the collective)
• Example code from this talk:
http://svn.plone.org/svn/plone/plone.dext
erity/example.ploneconf09

Thanks to everyone who has
contributed to making
Dexterity a reality!
http://www.fickr.com/photos/torley/2862255105/

Getting involved
• Google Code project:
http://code.google.com/p/dexterity/
• Google Group:
http://groups.google.com/group/dexterity-
development