Parent containers always created as Folder rather than the related @type as defined in parent

[zopyx]

Situation:

• fresh Plone 6.0.0a4 site
• importing a File.json
• some FIle objects have parents that are not Folder instances but more specialized DX container classes
• these parent folders are being created as Folder independent of @type value of the parent item:

https://github.com/collective/collective.exportimport/blob/main/src/collective/exportimport/import_content.py#L831

[zopyx]

The basic assumption that every parent is a Folder of this code

https://github.com/collective/collective.exportimport/blob/main/src/collective/exportimport/import_content.py#L816

is wrong. Parent containers can be arbitrary containerish types. This must be taken into account.

It also does not help (as a workaround) to import some container type before the other container type because there parents might be mixed in any arbitrary combination.

[zopyx]

There is perhaps another flaw in the parent handling. Our File.json contains an item https://nohost/eteaching/praxis/digital-learning-map-2020/180202_CfP_pdf.pdf with this parent:

 'parent': {'@id': 'https://nohost/eteaching/praxis/digital-learning-map-2020',
            '@type': 'eteaching.policy.projectsite',
            'description': 'Was macht Lernen mit digitalen Medien an '
                           'Hochschulen erfolgreich? Das untersuchte das vom '
                           'BMBF geförderte Projekt Digital Learning Map 2020 '
                           '(LearnMap). Das dreijährige Projekt lief von 2017 '
                           'bis Anfang 2020 am Leibniz-Institut für '
                           'Wissensmedien (IWM) in Tübingen und betrachtete '
                           'das Thema Digitalisierung von Hochschulen aus '
                           'unterschiedlichen Perspektiven.',
            'review_state': 'published',
            'title': 'Digital Learning Map 2020'},

With the current implementation, both parent folders praxis/digital-learning-map-2020 would be created as Folder which is wrong as discussed above. The container type for digital-learning-map-2020 could be created correctly with the information given from parent. However, there is no information about praxis which could a non-Folder too.

I think, we need

• the full parents information on the export side rather than only parent
• collective.exportimport would have to deal with multiple parents and arbitrary @type information for each parent rather than assuming Folder

[zopyx]

I implemented the @parents export through a customer export hook like

        def global_dict_hook(self, item, obj):
            """Use this to modify or skip the serialized data by type.
            Return the modified dict (item) or None if you want to skip this particular object.
            """

            def getAcquisitionChain(object):
                inner = object.aq_inner
                iter = inner
                while iter is not None:
                    yield iter
                    if ISiteRoot.providedBy(iter):
                       break
                    if not hasattr(iter, "aq_parent"):
                        raise RuntimeError("Parent traversing interrupted by object: " + str(parent))
                    iter = iter.aq_parent


            parents = list()

            p_chain = reversed(list(getAcquisitionChain(obj)))
            for p in p_chain:

                try:
                    state = get_state(p)
                except:
                    state = ""

                if p.portal_type != 'Plone Site' and p != obj:
                    parents.append({
                        "@id": p.absolute_url(),
                        "@type": p.portal_type,
                        "description": p.Description(),
                        "title": p.Title(),
                        "review_state": state
                        })

            item["parents"] = parents

[zopyx]

The following (ugly) code recreates the folderish objects with the correct portal_type and workflow state:

https://github.com/collective/collective.exportimport/blob/eteaching-fixes/src/collective/exportimport/import_content.py#L833-L862