Opened 6 years ago

Closed 6 years ago

#29504 closed Cleanup/optimization (wontfix)

JSONField dictionary/object lookup using an "integer" key

Reported by: Shaheed Haque Owned by: nobody
Component: Documentation Version: dev
Severity: Normal Keywords:
Cc: Carlton Gibson Triage Stage: Accepted
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description (last modified by Shaheed Haque)

The documentation on performing queries inside JSONField values https://docs.djangoproject.com/en/2.0/ref/contrib/postgres/fields/#key-index-and-path-lookups says:

If the key is an integer, it will be interpreted as an index lookup in an array:

>>> Dog.objects.filter(data__owner__other_pets__0__name='Fishy')

Note the specific mention of array. While this might be true, it is not the whole truth as applied to dict/object. For example, given a dict/object whose keys are strings (as always in JSON) but which look like integers:

  "employee": {
    "415": {
      "email": "Sherlock.Holmes@acme.co.uk",
      "mobile": "0700 1234567",

how is one supposed to select the "415" bit? It turns out that the same syntax as for the array case applies:

Foo.objects.filter(snapshot__employee__415__mobile='0700 1234567')

This was not at all obvious to me at least, especially as if the "415" is looked up as the final key in the query, the syntax becomes very different:

Foo.objects.filter(snapshot__employee__has_key='415')

Since I wasted quite a bit of time on this, I thought it might be useful to strengthen the documentation in this area to clarify how to lookup:

  • In arrays and dict/objects
    • if the key is the final term in the query
    • if the key is not the final term in the query

Change History (6)

comment:1 by Shaheed Haque, 6 years ago

Description: modified (diff)

comment:2 by Carlton Gibson, 6 years ago

Triage Stage: UnreviewedAccepted
UI/UX: unset
Version: 2.0master

OK, I'm going to provisionally accept this. If you can put together a patch we can have a look and see if there's a clarification to be made.

I'm half-minded to say wontfix since JSON keys must always be strings, and whilst, like '415', they might look like integers, there's no real ambiguity.
But lets see what improvement you have in mind. :)

comment:3 by Carlton Gibson, 6 years ago

Cc: Carlton Gibson added

comment:4 by Shaheed Haque, 6 years ago

I've created PR 10077. Please consider.

Last edited 6 years ago by Shaheed Haque (previous) (diff)

comment:5 by Shaheed Haque, 6 years ago

Has patch: set

comment:6 by Tim Graham, 6 years ago

Resolution: wontfix
Status: newclosed
Type: UncategorizedCleanup/optimization

Closing per discussion on PR.

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