#29504: JSONField dictionary/object lookup using an "integer" key
-------------------------------+--------------------------------------
Reporter: Shaheed Haque | Owner: nobody
Type: Uncategorized | Status: new
Component: Documentation | Version: 2.0
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 1
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Description changed by Shaheed Haque:
Old description:
> 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.hol...@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 terminal level 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
New description:
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.hol...@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
--
--
Ticket URL: <https://code.djangoproject.com/ticket/29504#comment:1>
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