Re: jsonb_set for nested new item? - Mailing list pgsql-general

From Deven Phillips
Subject Re: jsonb_set for nested new item?
Date
Msg-id CAJw+4ND1Vg__axTgh0aiwhR3vDPYVMfKRNEaMFnD1RwC5LYTMw@mail.gmail.com
Whole thread Raw
In response to jsonb_set for nested new item?  (Deven Phillips <deven.phillips@gmail.com>)
Responses Re: jsonb_set for nested new item?  (Vitaly Burovoy <vitaly.burovoy@gmail.com>)
List pgsql-general

Thanks for the confirmation. Unfortunately, I will need to handle more complex situations. I will look into creating a recursive subroutine to handle things.


On Sep 23, 2016 5:12 PM, "Vitaly Burovoy" <vitaly.burovoy@gmail.com> wrote:
On 9/23/16, Deven Phillips <deven.phillips@gmail.com> wrote:
> On Fri, Sep 23, 2016 at 10:14 AM, Deven Phillips <deven.phillips@gmail.com>
> wrote:
>
>> Is there a way to set a nested element for which the parent paths do not
>> yet exist?
>>
>> For example, if I have a JSONB value called 'data':
>>
>> {
>>     "foo": "bar"
>> }
>>
>> and run
>>
>> jsonb_set(data, {'boo', 'baz'}, 'newvalue')
>>
>> I would expect the output to be:
>>
>> {
>>     "foo": "bar",
>>     "boo": {
>>         "baz": "newvalue"
>>      }
>> }
>>
>> But that does not appear to work..
>>
>> Any suggestions would be appreciated.
>>
>
> Actually, it looks like I have to create all of the parent objects first
> before it would work... Is that correct?
>
> Deven

Yes, you are correct. The documentation[1] says:
> Returns target ... with new_value added if create_missing is true ...
> and the item designated by path does not exist.

There is nothing about a "path", only about a "new_value".
I think it is because of impossibility to understand what intermediate
objects are needed to be created (objects or arrays).

There is no easy way to create variadic intermediate objects, but in
your particular case (only one subobject) it can be like:

SELECT
    jsonb_set(
        CASE
            WHEN DATA ? 'boo'
                THEN DATA
                ELSE jsonb_set(DATA, array['boo'], '{}')
        END,
        '{boo,baz}'::text[],
        '"newvalue"'
    )
FROM (VALUES('{"foo": "bar"}'::jsonb)) AS t(data)


[1] https://www.postgresql.org/docs/devel/static/functions-json.html
--
Best regards,
Vitaly Burovoy

pgsql-general by date:

Previous
From: Joy Arulraj
Date:
Subject: Re: C++ port of Postgres
Next
From: René Leonhardt
Date:
Subject: Re: jsonb_set for nested new item?