Feedback-ID: ie0a040ee:Fastmail
Content-Type: multipart/mixed; boundary="------------fuCc1w0q4jXrRAzHBOccfMK4"
Message-ID: <0919c21e-af83-458b-8e40-1228429eaaa4@eisentraut.org>
Date: Wed, 4 Sep 2024 12:16:31 +0200
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: json_query conditional wrapper bug
From: Peter Eisentraut <peter@eisentraut.org>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
References: <8022e067-818b-45d3-8fab-6e0d94d03626@eisentraut.org>
Content-Language: en-US
In-Reply-To: <8022e067-818b-45d3-8fab-6e0d94d03626@eisentraut.org>
Archived-At: <https://www.postgresql.org/message-id/0919c21e-af83-458b-8e40-1228429eaaa4%40eisentraut.org>
Precedence: bulk

This is a multi-part message in MIME format.
--------------fuCc1w0q4jXrRAzHBOccfMK4
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

On 28.08.24 11:21, Peter Eisentraut wrote:
> These are ok:
> 
> select json_query('{"a": 1, "b": 42}'::jsonb, 'lax $.b' without wrapper);
>   json_query
> ------------
>   42
> 
> select json_query('{"a": 1, "b": 42}'::jsonb, 'lax $.b' with 
> unconditional wrapper);
>   json_query
> ------------
>   [42]
> 
> But this appears to be wrong:
> 
> select json_query('{"a": 1, "b": 42}'::jsonb, 'lax $.b' with conditional 
> wrapper);
>   json_query
> ------------
>   [42]
> 
> This should return an unwrapped 42.

If I make the code change illustrated in the attached patch, then I get 
the correct result here.  And various regression test results change, 
which, to me, all look more correct after this patch.  I don't know what 
the code I removed was supposed to accomplish, but it seems to be wrong 
somehow.  In the current implementation, the WITH CONDITIONAL WRAPPER 
clause doesn't appear to work correctly in any case I could identify.

--------------fuCc1w0q4jXrRAzHBOccfMK4
Content-Type: text/plain; charset=UTF-8;
 name="0001-WIP-Fix-JSON_QUERY-WITH-CONDITIONAL-WRAPPER.patch"
Content-Disposition: attachment;
 filename="0001-WIP-Fix-JSON_QUERY-WITH-CONDITIONAL-WRAPPER.patch"
Content-Transfer-Encoding: base64
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--------------fuCc1w0q4jXrRAzHBOccfMK4--