fredag den 2. august 2019 kl. 13.46.46 UTC+2 skrev Sage M.A.:
>
> As a follow-up to this message
> <https://groups.google.com/forum/#!msg/django-developers/M4dYz7T2SUo/b5RVjJHxBQAJ>
> and this ticket <https://code.djangoproject.com/ticket/12990>, I have
> completed the implementation of a cross-DB JSONField.
>
As someone who has been using the Postgres-specific JSONField extensively
for dynamic, custom fields for the past couple of years, can I humbly
suggest that the some more thought goes into the field lookup before the
current approach is enshrined?
The simple .filter(field__foo="hello world") is actually fine, but it gets
really weird if you let users define foo. What if they call foo something
like "contains"? What if "foo" is actually "Foo the bar?". The JSON makes
sense:
{
"Foo the bar?": true
}
but the Django filter does not.
The current documentation says you can use __contains, but as far as I can
tell, __contains, besides being difficult to understand, cannot be used for
queries like __icontains. And it overwrites a built-in, otherwise useful
operator.
My current wish list is:
- kill special contains and contained_by (use Q(field__foo="xxx") |
Q(field__bar="yyy") instead)
- kill has_keys and has_any_keys (use Q(field__has_key="xxx") |
Q(field__has_key="yyy") instead)
- add possibility of using something more robust than __ for path
traversal, perhaps just a JSON extract string like
JSONExtract("owner.other_pets[0].name")
This could perhaps also allow us to use the JSONField content in places
where you currently can't (e.g. annotate). I'm not sure how exactly to
combine it with field lookup and operators, but I'm personally okay with
something like
.filter(**{ "myfield__" + JSONExtract("owner.other_pets[0].name") +
"__icontains": "baz" })
That's way better than what we have now.
The neat thing about JSONField is that it can store some of the things that
are otherwise difficult to handle with traditional schemas. I think with
some love and a set of more orthogonal primitives, we could query it easily
from Django, too.
Ole
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