Re: [Modeling-users] Foreign Keys

[Yannick G. <yan...@sa...>]

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On July 23, 2003 10:09 am, Sebastien Bigaret wrote:
> > But if I have some of the records that have been
> > deleted, the PKs are not in a continuous sequence so FKs become out of
> > synch.
>
> Ok. But could you tell how you are doing this exactly? Are you
> building/inserting-in-ec new objects, then saving changes, or are you
> using some of the low-level functionalities to execute raw sql inserts,
> or something else? Asking this, because I'm trying to understand at
> which point exactly you need to provide the PK, where it is stored, etc.

Ehh humm like this :

            exec ("global %s" % childClassName)
            exec (importCmd % (childClassName, childClassName))

            posElem = xpath.Evaluate(("./%s/text()" % fkStr), elem)[0]
            curPos = int(posElem.nodeValue)

            i18nPath = '/db_dump/%s[%s/text()="%d"]' % ( childClassName,
                                                         fkStr,
                                                         curPos )
            i18nElems = xpath.Evaluate(i18nPath, self.i18nDoc)

            # create i18ns
            for i18nElem in i18nElems:
                i18nObj = eval("%s()" % childClassName)
                self.fillObject(i18nObj, i18nElem)
                obj.addObjectToBothSidesOfRelationshipWithKey(i18nObj, 'i18n')
                self.ec.insertObject(i18nObj)
            self.ec.insertObject(obj)


I process the table dumps 2 by 2, one for the master, one for i18ns.
I must admit that I don't know how I will restore the more complex
relations.  The way I do it now fix the missing PKs problem because I
find the matching ones in the i18n dump with i18nPath but it's a hack,
a really slow hack.  I have to do a XPath query on a 1400 nodes file
700 time : 300 secs avg.

So skiping PKs would be much more simple but having the framework
doing the dump and restoration would be even beter.  I do the dump
like this (phpMyAdmin is full Latin-1) :

if __name__ == "__main__":
    if not len(sys.argv) == 2:
        print "USAGE : dump_xml.py <entity-name>"
        sys.exit(1)

    sys.path.append("..")

    entityName = sys.argv[1]
    ec = EditingContext()
    mm = ModelManager(ec)

    importCmd = "from Autogen.%s import %s" % (entityName, entityName)
    exec(importCmd)

    objs = mm.fetch(entityName)

    # get the primary key name
    key = ec.globalIDForObject(objs[0]).keyValues().keys()[0]

    objs = map(lambda obj:mm.snapshot(obj), objs)

    objs = sortById(objs, key)

    domDoc = getDomDoc()
    for obj in objs:
        elem = domDoc.createElement(entityName)
        for key in obj.keys():
            tagName = externalNameForInternalName(key).lower()
            property = domDoc.createElement(tagName)
            if key != "i18n":
                elem.appendChild(property)
                dataStr = toStr(obj[key])
                data = domDoc.createTextNode(dataStr)
                property.appendChild(data)
        xpath.Evaluate("/db_dump", domDoc)[0].appendChild(elem)

    PrettyPrint(domDoc)


Yes, i18n is hardcoded... : \

- --
Yannick Gingras
Byte Gardener, Savoir-faire Linux inc.
(514) 276-5468


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