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Slight extension of get/setRelationSingle() to allow for using for attribute on 'second'

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git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@1083 fd906abe-77d9-0310-91a1-e0d9ade77398
This commit is contained in:
helmutm 2006-02-18 10:56:14 +00:00
parent b79cfea129
commit dc5c09afdd
2 changed files with 12 additions and 6 deletions
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1
__init__.py
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@ -1,4 +1,3 @@
""" """
$Id$ $Id$
""" """

17
relation/registry.py
View file

@ -162,29 +162,36 @@ def getRelations(first=None, second=None, third=None, relationships=None):
result.update(registry.query(**query)) result.update(registry.query(**query))
return result return result
def getRelationSingle(first, relationship): def getRelationSingle(obj=None, relationship=None, forSecond=True):
""" Returns the one and only relation for first having relationship """ Returns the one and only relation for first having relationship
or None if there is none. or None if there is none.
Raise an error if there is more than one hit. Raise an error if there is more than one hit.
""" """
rels = getRelations(first, relationships=[relationship]) if forSecond:
rels = getRelations(second=obj, relationships=[relationship])
else:
rels = getRelations(first=obj, relationships=[relationship])
if len(rels) == 0: if len(rels) == 0:
return None return None
if len(rels) > 1: if len(rels) > 1:
raise ValueError('Multiple hits when only one relation expected: ' raise ValueError('Multiple hits when only one relation expected: '
'%s, relationship: %s' % (zapi.getName(first), '%s, relationship: %s' % (zapi.getName(obj),
relationship.getPredicateName())) relationship.getPredicateName()))
return list(rels)[0] return list(rels)[0]
def setRelationSingle(relation): def setRelationSingle(relation, forSecond=True):
""" Register the relation given, unregistering already existing """ Register the relation given, unregistering already existing
relations for first and relationship. After this operation there relations for first and relationship. After this operation there
will be only one relation for first with the relationship given. will be only one relation for first with the relationship given.
""" """
first = relation.first first = relation.first
second = relation.second
registry = zapi.getUtility(IRelationRegistry) registry = zapi.getUtility(IRelationRegistry)
rels = list(registry.query(first=first, relationship=relation)) if forSecond:
rels = list(registry.query(second=second, relationship=relation))
else:
rels = list(registry.query(first=first, relationship=relation))
for oldRel in rels: for oldRel in rels:
registry.unregister(oldRel) registry.unregister(oldRel)
registry.register(relation) registry.register(relation)