[Grok-dev] object relationships

Jeroen Michiel jmichiel at yahoo.com
Thu Jan 29 11:17:44 EST 2009

OK, I got it working!

This is how I managed it:

First of all, the IIntIds utility and a RelationCatalog need to be
registered, so I made an event subscription to grok.IObjectAddedEvent to do

@grok.subscribe(Test, grok.IObjectAddedEvent)
def added(app, event):
     app['intids'] = intids = IntIds()
     app['catalog'] = catalog = relationfield.RelationCatalog()

you also need an IObjectPath implementation, so I did this:
class ObjectPath(grok.GlobalUtility):
    def path(self, obj):
        return path(grok.getSite(), obj)
    def resolve(self, path):
        return resolve(grok.getSite(), path)

Then I have some data I want to refer to:
class IReferedData(Interface):
    name = schema.TextLine(title=u'The Name')

class ReferedData(grok.Model):
    grok.implements(IReferedData, IHasIncomingRelations)
    def __init__(self, Name):
        self.name = Name

The the data that has a reference to ReferedData:
class ITestData(Interface):
    rel = relationfield.Relation(title=u'Relation')

class TestData(grok.Model):
    grok.implements(ITestData, HasOutgoingRelations)

and in my add form I do this:
class Add(grok.AddForm):
    form_fields = grok.Fields(ITestData,
select=schema.Choice(title=u'Relation', source=TestSource())).omit('rel')

    def Add(self, **data):
        testdata = TestData()
        intids = component.getUtility(IIntIds)
        id = intids.getId(data['select'])
        del data['select']
        self.applyData(testdata, **data)
        testdata.rel = relationfield.RelationValue(id)  
        grok.getSite()['testdata'][str(len(grok.getSite()['testdata']))] =

(the applyData is strictly not necessary, but will be if there would be
other fields associated to ITestData)

And that seems to do it! I can search relations and everything.

Anyone who has any remarks about things I should have done differently
perhaps, let me know, I can only learn from it.
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