Export_content and export_relations together?

Plone Support Add-on Development
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1

Specifically to @pbauer and @fredvd

What were the decisions that lead to a relation export being separate from a content export?

My first instinct is to get these relation fields directly into exported content- probably as URL's, rather than a separate export. Since my content is leaving Plone and going somewhere else ( :cry: :sob:).

But before I go down the path of combining relations and content exports into one export file, is there a big headache coming my way I don't see yet?

2

The problem here is chicken and egg. When you import a content item from the content.json, it passes the plone.restapi deserialisation calls and also all validators are run. When you want to recreate a relation like on the related items, you need to instantiate and persist a RelationValue.

If the target content item you want to relate to hasn't been imported yet into the Plone site, you basically can't. The current solution is to have a 2 phase import: create the content tree in phase1, re-apply al relations in phase 2 when all content is there.

An alternative solution would be to store the relations in the content.json file, but make the import process smart by pushing al relations onto a queue in memory or a temporary annotation on the site root or wherever, and process the queue after all content has been imported. Still 2 phases, but store the relations in the content itself.

We could simplify the import for other 'metadata' values like the default page as well. There we have the same problem: if you try to set a content item as default page on a folder, but the content item itself hasn't been created yet in the folder, you can't set that default page.

3

Thanks.

If it's an import issue, then I can avoid it. (This makes me super sad, but I have a therapist).

The new CMS doesn't have the validation on import and the object's reference error is postponed until rendering (this referenced image isn't here: 404).

So, yes. My export can (and will) contain references. Thank you @fredvd for this insight.

Edit:

In the transmogrifier days, we used to just import twice - ignoring the errors on the first round :nerd_face:

But the "right" way to do it was to catch the validation error and annotate the pipeline to "try this guy again", and a source would pull in those for a second try. But who uses transmogrifier anymore?