PageQuerySet.specific docs should mention filtering/ordering restrictions

As suggested at https://stackoverflow.com/a/55532616/1853523, the docs for PageQuerySet.specific should:

• go into more detail about the sequence of queries that happens internally
• explain that adding specific() to a queryset expression does not make fields from the specific page available for use within filter / order_by clauses
• mention that if your query is targetting one Page subclass in particular, you can work around this by reorganising your query to not require specific, e.g. article_index_page.get_children().specific() becomes ArticlePage.objects.child_of(article_index_page)
• possibly also mention that the above workaround won’t help you if you have multiple page types with same-named fields on them (because they aren’t actually the same field from the database’s point of view).

[gasman]

@brylie Assuming field_on_model is a field defined on the Contact model, then Contact.objects.child_of(self).filter(field_on_model="something") (without the specific()) should work.

[brylie]

Thanks for the quick response! It works! Will be glad to see this in the docs, as I have been spending nearly one hour trying to figure this out by guesswork 😃