This talk covers the basics of building content types with Dexterity, and how it compares to doing so with Archetypes; what sorts of tasks Dexterity is best suited for, and which ones it isn't ready for yet * an update on the most recent improvements to Dexterity

1. A Dexterity Intro for Recovering
Archetypes Addicts
David Glick
Plone Symposium East, 2010

2. What is a content type?

3. ZODB stores objects

4. Content type (or portal_type)
categorizes objects
Page Something Else

5. Schema
(what sort of data can be stored)

6. Workflow
(who can do things when)

7. Custom view templates
(what it looks like)

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

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

10. 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

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

12. Dexterity
Martin Aspeli

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

14. Make filesystem content type
development sane

15. Make through-the-web content
type development possible

16. Make it possible to switch
back and forth between the 2

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

18. Reuse over reinvention

19. 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

20. Natural interaction over
excessive generality
understanding
time

21. Real code over generated
code

22. Zope 3 over Zope 2

23. Automated testing over
wishful thinking

24. Example: Photo Gallery
(example.dexgallery in the collective)
• Photo Gallery content type
• Photo content type
• Tagging
• Geolocation

26. Rapid Development
Archetypes Dexterity
• ArchGenXML • collective.dexteritypaste
• ZopeSkel $ bin/zopeskel dexterity
• Though-the-web
content type creation

27. TTW type development

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

29. Base class
Archetypes Dexterity
• BaseObject, usually via • plone.dexterity.content.Item or
plone.dexterity.content.Container
ATContentTypes
• fewer mixins
• many mixins
• custom subclasses
• typically need a custom typically unneeded
subclass

30. Schemas
Archetypes Dexterity
• unique schema format • Zope 3 schemas
• define a schema, assign it • Can also be represented in
to the content class's a unique XML schema
'schema' attribute format
• Associated with a content
type via the FTI in
portal_types

31. 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

32. Schemas
Archetypes Dexterity
From content/photo.py: From content/photo.py:
PhotoSchema = atapi.Schema(( class IPhoto(form.Schema):
# (fields here) # (fields here)
))
From profles/default/types/photo.xml:
schemata.finalizeATCTSchema(PhotoSchema,
moveDiscussion=False) <property name="schema">
example.dexgallery.dexterity.content.photo.
class Photo(base.ATCTContent): IPhoto
implements(IPhoto) </property>
meta_type = "Photo"
schema = PhotoSchema

33. Accessing fields
Archetypes Dexterity
• obj.getField('fieldname') • obj.fieldname
.get(obj) (values are simply stored
• obj.getFieldname() as attributes)
(magically generated • Use property descriptors if
accessor on the content you need custom accessor/
class) mutator logic
• __getattr__ makes sure to
get default value from
schema if there's no
attribute stored yet

34. Field security
• Controlled access (from RestrictedPython)
• Implemented using
__allow_access_to_unprotected_subobjects__
Archetypes Dexterity
• Read/write permissions • Read/write permissions
can be specified per field can be specified per field
in the schema in the schema

35. Caption field (rich text)
Archetypes Dexterity
From content/photo.py: From content/photo.py:
atapi.TextField('caption', from plone.app.textfield import RichText
required = False,
searchable = True, caption = RichText(
storage = title = _(u'Caption'),
atapi.AnnotationStorage(migrate=True), required = False,
validators = )
('isTidyHtmlWithCleanup',),
default_content_type = 'text/html',
default_output_type = 'text/x-html-
safe',
widget = atapi.RichWidget(
label = _(u'Caption'),
),
),

36. Photo field (image)
Archetypes
from plone.app.blob.field import ImageField
ImageField('image',
required = True,
storage = atapi.AnnotationStorage(migrate=True),
languageIndependent = True,
swallowResizeExceptions =
zconf.swallowImageResizeExceptions.enable,
pil_quality = zconf.pil_config.quality,
pil_resize_algo = zconf.pil_config.resize_algo,
max_size = zconf.ATNewsItem.max_image_dimension,
validators = (('isNonEmptyFile', V_REQUIRED),
('checkNewsImageMaxSize', V_REQUIRED)),
widget = atapi.ImageWidget(
label = _(u'Photo'),
show_content_type = False
),
),
Dexterity
from plone.namedfile.field import NamedBlobImage
image = NamedBlobImage(
title = _(u'Photo'),
)

37. Image scaling
• Now supports arbitrary sizes, e.g.
<img tal:defne="scale photo_obj/@ @ images"
tal:replace="structure python:scale.scale('image', width=1200,
height=300, direction='keep').tag()"/>
• (supported for both Archetypes and
Dexterity in Plone 4)

38. Tags field (relations)
Archetypes Dexterity
From content/photo.py: From content/photo.py:
atapi.ReferenceField( from z3c.relationfield.schema import
'tags', RelationList, RelationChoice
storage=atapi.AnnotationStorage(), tags = RelationList(
widget=atapi.ReferenceWidget( title = _(u'Tags'),
label=_(u"Tags"), default = [],
), value_type=RelationChoice(
required=False, title = _(u'Tag'),
relationship='photo_tag', source = ObjPathSourceBinder(
allowed_types=('Document',), navigation_tree_query = {'path':
multiValued=True, {'query':'/'}},
), portal_type = 'Document',
),
),
required = False,
)

39. Content tree widget

40. Indexing fields
• similar for both
• for Dexterity you may need to implement
your own SearchableText indexer, e.g.
from plone.indexer import indexer
@indexer(IPhoto)
def SearchableText(obj):
return ' '.join([obj.Title(), obj.Description(), obj.caption.output])

41. Custom views
Archetypes Dexterity
• default: base_view.cpt • default: view class in
• add a skin layer template plone.dexterity.browser.view
or browser view, register • add a skin layer template or
in the FTI browser view, register in the
FTI

42. Grok-style configuration
• Configuration via directives inline with
code, instead of via ZCML declarations. e.g.
from five import grok
class View(grok.View):
grok.context(IPhoto)
grok.require('zope2.View')
• Supported but not required

43. Custom forms
Archetypes Dexterity
• difficult • full power of z3c.form
(write custom forms that
reference fields from the
type's schema)
• or, use grok directives on the
schema to influence how
fields appear in all forms (e.g.,
custom widget, etc.)

44. Adding items
Archetypes Dexterity
• Autogenerated factory • z3c.form add form
method • Default works in many
• In Plone, portal_factory cases, but can be replaced
prevents premature by setting add_view_expr
creation and indexing in the FTI
• No content is constructed
until the form is submitted

45. Extending content types
Archetypes Dexterity
• archetypes.schemaextender • “behaviors”
• “schema extender” adapters • can provide additional
can provide additional fields fields
• “schema modifier” adapters • can mark the content item
can make arbitrary changes with a particular interface
to a schema • can be turned on/off
through the web for each
content type

46. 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

47. Geolocation behavior

48. Geolocation behavior
• Adds a geolocation field
• Provides an adapter to store the value of
that field in an annotation
• Marks the item with IGeolocatableMarker
• Some adapters so that Products.Maps
knows how to get a geolocation from an
item with IGeolocatableMarker

49. Registering a type
Archetypes Dexterity
• registerType() after class • Just GenericSetup
definition magically (profiles/default/types/
generates Zope 2-style [Type_Id].xml)
factory methods
• boilerplate in __init__.py
finds types and completes
registration
• type configuration in
GenericSetup profile
references the factory
method

50. """Main product initializer from zope.i18nmessageid import MessageFactory
"""
_ = MessageFactory('example.dexgallery')
from zope.i18nmessageid import MessageFactory
from example.dexgallery.archetypes import config
from Products.Archetypes import atapi
from Products.CMFCore import utils
# Define a message factory for when this product is internationalised.
# This will be imported with the special name "_" in most modules. Strings
# like _(u"message") will then be extracted by i18n tools for translation.
archetypesMessageFactory = MessageFactory('example.dexgallery.archetypes')
def initialize(context):
"""Initializer called when used as a Zope 2 product.
This is referenced from configure.zcml. Regstrations as a "Zope 2 product"
is necessary for GenericSetup profiles to work, for example.
Here, we call the Archetypes machinery to register our content types
with Zope and the CMF.
"""
# Retrieve the content types that have been registered with Archetypes
# This happens when the content type is imported and the registerType()
# call in the content type's module is invoked. Actually, this happens
# during ZCML processing, but we do it here again to be explicit. Of
# course, even if we import the module several times, it is only run
# once.
content_types, constructors, ftis = atapi.process_types(
atapi.listTypes(config.PROJECTNAME),
config.PROJECTNAME)
# Now initialize all these content types. The initialization process takes
# care of registering low-level Zope 2 factories, including the relevant
# add-permission. These are listed in config.py. We use different
# permissions for each content type to allow maximum flexibility of who
# can add which content types, where. The roles are set up in rolemap.xml
# in the GenericSetup profile.
for atype, constructor in zip(content_types, constructors):
utils.ContentInit('%s: %s' % (config.PROJECTNAME, atype.portal_type),
content_types=(atype, ),
permission=config.ADD_PERMISSIONS[atype.portal_type],
extra_constructors=(constructor,),
).initialize(context)

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

52. Core functionality

53. Schema serialization

54. Automatic form
generation

55. Portlet assignments

56. Content rules

57. Relations
• Support for referencing Dexterity content
from AT content is in progress

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

59. TTW schema editing

60. Image & file support
(via plone.namedfile)

61. Text transform support
(via plone.app.textfield)

62. WebDAV support

63. Versioning & staging
• In progress

64. TTW behavior creation

65. Automatic migration
from Archetypes
content

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

67. Link integrity checks

68. Upcoming releases
• First beta release was on Apr. 20
• But, being used in production
• Future releases will support upgrades

69. Compatibility
• Plone 3
• Plone 4

70. Performance

71. Further information
• Installation howto:
http://plone.org/products/dexterity/documentation/how
-to/install
• Dexterity manual:
http://plone.org/products/dexterity/documentation/man
ual/developer-manual
• Behaviors manual:
http://plone.org/products/dexterity/documentation/man
ual/behaviors

72. Example Code
• example.dexterity
• example.conference
• example.dexgallery
(in the collective)

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

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