infrae.plone.relations.schema 1.0

Zope 3 schema for plone.app.relations items.

Contents

• Interface definition

• Create a simple content for test purpose

  • Utility to display relation

• Simple field use

  • Direct set, and reverse access

  • Deletion

  • Field independence

• More Constraints

• Use of context object

• Many to Many Relation Interface

  • Simple test of the interface

  • Direction

  • Bigger example with transitivity

  • Accessor

  • Deletion

• Changes

• Credits

The purpose of this extension is to provide a Zope 3 schema for plone relations. This has been tested with Plone 2.5 and Plone 3.

Interface definition

A new field:

>>> from infrae.plone.relations.schema import PloneRelation

A simple interface with an field:

>>> from zope.interface import Interface, implements
>>> class IContent(Interface):
...    """Sample interface."""
...    relation = PloneRelation(relation="my relation")

I can get the field from the interface:

>>> r_field = IContent.get('relation')

And this is a field:

>>> from zope.interface.verify import verifyObject
>>> from zope.schema.interfaces import IField
>>> verifyObject(IField, r_field)
True

Now, a field to look up reverse relations:

>>> class IBackContent(Interface):
...    """Sample interface."""
...    relation = PloneRelation(relation="my relation",
...                             reverse=True)

Create a simple content for test purpose

And a simple implementation:

>>> from OFS.Folder import Folder
>>> class BaseContent(Folder):
...    def __init__(self, id):
...       super(BaseContent, self).__init__()
...       self.id = id
...    def UID(self):
...       return 'uid-%s' % self.id

UID are used by the context factory.

Standard base class:

>>> class MyContent(BaseContent):
...    implements(IContent)

And:

>>> class MyBackContent(BaseContent):
...    implements(IBackContent)

Now, create some items:

>>> for id in range(1, 5):
...    name = 'it%d' % id
...    item = MyContent(name)
...    self.portal._setObject(name, item)
'it1'
'it2'
'it3'
'it4'
>>> it1 = self.portal.it1
>>> it2 = self.portal.it2
>>> it3 = self.portal.it3
>>> it4 = self.portal.it4

>>> itb1 = MyBackContent('itb1')
>>> self.portal._setObject('itb1', itb1)
'itb1'
>>> itb1 = self.portal.itb1

Utility to display relation

An helper to display a relation:

>>> def display(rels):
...     for rel in rels:
...        print "Objects: %s" % list(rel['objects'])
...        if rel.has_key("context"):
...            print "Context: %s" % rel['context']
...     if not rels:
...        print "Empty"

Simple field use

Direct set, and reverse access

And try some validation on data. Data is a list of dictionary, representing all relations of the field. In the dictionary:

• objects: represent a list of object for the relation;

• context: may be an object stored as context of the relation.

Example:

>>> bad_relation1 = [{'bad': None},]
>>> r_field.validate(bad_relation1)
Traceback (most recent call last):
  ...
ValidationError: Invalid structure
>>> good_relation = [{'objects': [it2, itb1]},]
>>> r_field.validate(good_relation)

And set the field:

>>> r_field.set(it1, good_relation)

And get data from the field:

>>> relation = r_field.get(it1)
>>> relation
[{'objects': <plone.relations.relationships.IntIdSubObjectWrapper object at ...>}]
>>> display(relation)
Objects: [<MyContent at /plone/it2>, <MyBackContent at /plone/itb1>]

Now, we can ask from itb1 content, which has a reverse field:

>>> rb_field = IBackContent.get('relation')
>>> relation = rb_field.get(itb1)
>>> relation
[{'objects': <plone.relations.relationships.IntIdSubObjectWrapper object at ...>}]
>>> display(relation)
Objects: [<MyContent at /plone/it1>]

We update the relation:

>>> good_relation = [{'objects': [it2, it3]},]
>>> r_field.set(it1, good_relation)

So change is reflected:

>>> display(r_field.get(it1))
Objects: [<MyContent at /plone/it2>, <MyContent at /plone/it3>]

And there is no more relation in the reverse field:

>>> rb_field = IBackContent.get('relation')
>>> rb_field.get(itb1)
[]

Now, set on reverse field:

>>> good_relation = [{'objects': [it1, it2]}]
>>> rb_field.set(itb1, good_relation)
>>> display(rb_field.get(itb1))
Objects: [<MyContent at /plone/it1>, <MyContent at /plone/it2>]

And on the normal:

>>> display(r_field.get(it1))
Objects: [<MyContent at /plone/it2>, <MyContent at /plone/it3>]
Objects: [<MyBackContent at /plone/itb1>]

Deletion

You can delete value by setting the relation to an empty list []:

>>> display(r_field.get(it2))
Objects: [<MyBackContent at /plone/itb1>]
>>> r_field.set(it2, [])
>>> display(r_field.get(it2))
Empty
>>> display(rb_field.get(itb1))
Objects: [<MyContent at /plone/it1>]

And:

>>> display(r_field.get(it1))
Objects: [<MyContent at /plone/it2>, <MyContent at /plone/it3>]
Objects: [<MyBackContent at /plone/itb1>]
>>> r_field.set(it1, [])
>>> display(r_field.get(it1))
Empty
>>> display(rb_field.get(itb1))
Empty

Field independence

One other relation schema:

>>> class IComplexContent(Interface):
...    """A content with two relation."""
...    relation1 = PloneRelation(relation="relation1")
...    relation2 = PloneRelation(relation="relation2")

And the related content:

>>> class MyComplexContent(BaseContent):
...    implements(IComplexContent)

Create three objects like this:

>>> itcx1 = MyComplexContent("itcx1")
>>> self.portal._setObject("itcx1", itcx1)
'itcx1'
>>> itcx1 = self.portal.itcx1
>>> itcx2 = MyComplexContent("itcx2")
>>> self.portal._setObject("itcx2", itcx2)
'itcx2'
>>> itcx2 = self.portal.itcx2
>>> itcx3 = MyComplexContent("itcx3")
>>> self.portal._setObject("itcx3", itcx3)
'itcx3'
>>> itcx3 = self.portal.itcx3

Now, add relation:

>>> r1_field = IComplexContent.get("relation1")
>>> r1_field.set(itcx1, [{'objects': [itcx2,]}])
>>> display(r1_field.get(itcx1))
Objects: [<MyComplexContent at /plone/itcx2>]
>>> r2_field = IComplexContent.get("relation2")
>>> r2_field.set(itcx1, [{'objects': [itcx3,]}])
>>> display(r2_field.get(itcx1))
Objects: [<MyComplexContent at /plone/itcx3>]

And delete one:

>>> r2_field.set(itcx1, [])
>>> display(r2_field.get(itcx1))
Empty
>>> display(r1_field.get(itcx1))
Objects: [<MyComplexContent at /plone/itcx2>]

More Constraints

Now, you have to give at least 1 value, and no more than 3:

>>> class ILengthContent(Interface):
...    """Sample interface with length control."""
...    relation = PloneRelation(relation="my relation",
...                             min_length=1,
...                             max_length=3)

The field implements IMinMaxLen:

>>> from zope.schema.interfaces import IMinMaxLen
>>> rl_field = ILengthContent.get('relation')
>>> verifyObject(IMinMaxLen, rl_field)
True

Ok, now some bad tries:

>>> bad_relation = []
>>> rl_field.validate(bad_relation)
Traceback (most recent call last):
  ...
TooSmall: Less than 1 values

>>> bad_relation = [{'objects': [it2,]},
...                 {'objects': [it3,]},
...                 {'objects': [it4,]},
...                 {'objects': [itb1,]},]
>>> rl_field.validate(bad_relation)
Traceback (most recent call last):
  ...
TooBig: More than 3 values

And now, one correct:

>>> good_relation = [{'objects': [it2,]},]
>>> rl_field.validate(good_relation)

But we want also to have uniques objects in the relation:

>>> class IUniqueContent(Interface):
...    """Sample interface only one item per relation."""
...    relation = PloneRelation(relation="my relation",
...                             unique=True)
>>> ru_field = IUniqueContent.get('relation')

Some tries now:

>>> bad_relation = [{'objects': [it2, it3,]}]
>>> ru_field.validate(bad_relation)
Traceback (most recent call last):
  ...
ValidationError: Not uniques values in relation

>>> good_relation = [{'objects': [it2,]}]
>>> ru_field.validate(good_relation)

We want that every object in the relation implements a particular interface:

>>> class IConstraintContent(Interface):
...    """Sample interface with constraint on relation."""
...    relation = PloneRelation(relation="my relation",
...                             relation_schema=IUniqueContent)
>>> rs_field = IConstraintContent.get('relation')

Use of context object

Two interfaces let you work with context objects:

>>> from infrae.plone.relations.schema import IPloneRelationContext
>>> from infrae.plone.relations.schema import IPloneRelationContextFactory

This two next import are helpers, but you can use them since it’s good content start:

>>> from infrae.plone.relations.schema import BasePloneRelationContext
>>> from infrae.plone.relations.schema import BasePloneRelationContextFactory

The following context interface:

>>> class IContextObject(IPloneRelationContext):
...    """Simple context object."""

And its corresponding object:

>>> class MyContextObject(BasePloneRelationContext):
...    implements(IContextObject)

We will declare the field like this:

>>> class IContentWithContext(Interface):
...    """Simple content with a context."""
...    relation = PloneRelation(relation="context relation",
...                             context_schema=IContextObject)

We want an object with this schema:

>>> class MyContentWithContext(BaseContent):
...    implements(IContentWithContext)

Create the object:

>>> itc1 = MyContentWithContext('itc1')
>>> self.portal._setObject('itc1', itc1)
'itc1'
>>> itc1 = self.portal.itc1

Prepare one context object:

>>> ctxt_fac = BasePloneRelationContextFactory(MyContextObject, IContextObject)
>>> verifyObject(IPloneRelationContextFactory, ctxt_fac)
True
>>> ctxt1 = ctxt_fac(itc1, it1, dict())
>>> ctxt1
<MyContextObject at /plone/itc1/uid-it1>
>>> verifyObject(IContextObject, ctxt1)
True

Get the field:

>>> rc_field = IContentWithContext.get('relation')

Now we can try this relation:

>>> bad_relation = [{'objects': [it2, itb1,], 'context': it3,}]
>>> rc_field.validate(bad_relation)
Traceback (most recent call last):
  ...
ValidationError: Invalid context
>>> good_relation = [{'objects': [it2, itb1,], 'context': ctxt1,}]
>>> rc_field.validate(good_relation)
>>> rc_field.set(itc1, good_relation)

If we consult the relation:

>>> display(rc_field.get(itc1))
Objects: [<MyContent at /plone/it2>, <MyBackContent at /plone/itb1>]
Context: <MyContextObject at uid-it1>

Many to Many Relation Interface

This interface provides a more generic way to edit relations than the one provided by plone.app.relations, to let the Zope 3 schema work in both way (normal access to the relation, and reverse access).

Create simple content:

>>> from OFS.SimpleItem import SimpleItem
>>> class BaseContent(SimpleItem):
...    def __init__(self, id):
...       super(BaseContent, self).__init__()
...       self.id = id


>>> for num in range(1, 20):
...    id = 'it%02d' % num
...    it = BaseContent(id)
...    _ = self.portal._setObject(id, it)

>>> self.portal.it01
<BaseContent at /plone/it01>

Contents must be IPersistent:

>>> from persistent import IPersistent
>>> from zope.interface.verify import verifyObject
>>> verifyObject(IPersistent, self.portal.it01)
True

Simple test of the interface

We have a new adapter to work on your relation:

>>> from infrae.plone.relations.schema import IManyToManyRelationship
>>> manager = IManyToManyRelationship(self.portal.it01)
>>> verifyObject(IManyToManyRelationship, manager)
True

Ok, try to add relation:

>>> rel = manager.createRelationship((self.portal.it11, self.portal.it12,),
...                                  sources=(self.portal.it02,),
...                                  relation='test')
>>> list(rel.sources)
[<BaseContent at /plone/it01>, <BaseContent at /plone/it02>]
>>> list(rel.targets)
[<BaseContent at /plone/it11>, <BaseContent at /plone/it12>]

Now, we can retrieve a list of relation:

>>> list(manager.getRelationships())
[<Relationship 'test' from (<BaseContent at /plone/it01>, <BaseContent at /plone/it02>) to (<BaseContent at /plone/it11>, <BaseContent at /plone/it12>)>]

Direction

You can reverse the way a relation works, with the setDirection method:

>>> rel = manager.createRelationship(self.portal.it05, relation='reverse')
>>> list(rel.targets)
[<BaseContent at /plone/it05>]
>>> manager.setDirection(False)
>>> rel = manager.createRelationship(self.portal.it04, relation='reverse')
>>> list(rel.targets)
[<BaseContent at /plone/it01>]

You have also the transitivity for search:

>>> manager = IManyToManyRelationship(self.portal.it04)
>>> list(manager.getRelationshipChains(relation='reverse',
...                                    target=self.portal.it05,
...                                    maxDepth=2))
[(<Relationship 'reverse' from (<BaseContent at /plone/it04>,) to (<BaseContent at /plone/it01>,)>, <Relationship 'reverse' from (<BaseContent at /plone/it01>,) to (<BaseContent at /plone/it05>,)>)]

But relation are always followed from source to target. So if we reverse the search, we won’t found a result:

>>> manager.setDirection(False)
>>> list(manager.getRelationshipChains(relation='reverse',
...                                    target=self.portal.it05,
...                                    maxDepth=2))
[]

Direction just change the meaning of source or target on the relation object. It’s doesn’t change the relation itself.

Bigger example with transitivity

Taking back the first test, and add a suite:

>>> manager = IManyToManyRelationship(self.portal.it16)
>>> manager.setDirection(False)
>>> rel = manager.createRelationship((self.portal.it12, self.portal.it14),
...                                  relation='test')
>>> manager.setDirection(True)
>>> rel = manager.createRelationship((self.portal.it17, self.portal.it18),
...                                  sources=(self.portal.it19,),
...                                  relation='test')

New chain try:

>>> manager = IManyToManyRelationship(self.portal.it02)
>>> list(manager.getRelationshipChains(relation='test',
...                                    target=self.portal.it18,
...                                    maxDepth=3))
[(<Relationship 'test' from (<BaseContent at /plone/it01>, <BaseContent at /plone/it02>) to (<BaseContent at /plone/it11>, <BaseContent at /plone/it12>)>, <Relationship 'test' from (<BaseContent at /plone/it12>, <BaseContent at /plone/it14>) to (<BaseContent at /plone/it16>,)>, <Relationship 'test' from (<BaseContent at /plone/it16>, <BaseContent at /plone/it19>) to (<BaseContent at /plone/it17>, <BaseContent at /plone/it18>)>)]

Accessor

getTargets returns a lazy list of objects having a relation with the given object as source, and getSources returns a lazy list of objects having a relation with the given object as target:

>>> manager = IManyToManyRelationship(self.portal.it16)
>>> list(manager.getTargets())
[<BaseContent at /plone/it17>, <BaseContent at /plone/it18>]
>>> list(manager.getSources())
[<BaseContent at /plone/it12>, <BaseContent at /plone/it14>]

If we reverse the direction:

>>> manager.setDirection(False)
>>> list(manager.getTargets())
[<BaseContent at /plone/it12>, <BaseContent at /plone/it14>]
>>> list(manager.getSources())
[<BaseContent at /plone/it17>, <BaseContent at /plone/it18>]

Deletion

Delete relation:

>>> manager.setDirection(True)
>>> manager.deleteRelationship()
>>> list(manager.getRelationships())
[]

>>> manager = IManyToManyRelationship(self.portal.it19)
>>> list(manager.getRelationships())
[<Relationship 'test' from (<BaseContent at /plone/it19>,) to (<BaseContent at /plone/it17>, <BaseContent at /plone/it18>)>]

>>> manager.deleteRelationship(target=self.portal.it17)
>>> list(manager.getRelationships())
[<Relationship 'test' from (<BaseContent at /plone/it19>,) to (<BaseContent at /plone/it18>,)>]

>>> manager.deleteRelationship()
>>> list(manager.getRelationships())
[]

>>> manager = IManyToManyRelationship(self.portal.it01)
>>> manager.deleteRelationship(remove_all_sources=True, multiple=True)
>>> manager = IManyToManyRelationship(self.portal.it02)
>>> list(manager.getRelationships())
[]

Changes

1.0

• First release.

Credits

Powered by the Flemish government of Belgium, for the application <http://www.zonderisgezonder.be>.