Re: Extracting data from jsonb array?

On Mon, Dec 7, 2020 at 3:22 PM David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
wrote:

> On Mon, Dec 7, 2020 at 4:13 PM Steve Baldwin <steve(dot)baldwin(at)gmail(dot)com>
> wrote:
>
>> Try:
>>
>> select _message_body->'Charges'->>'Name' from ...
>>
>
> Not so much..."Charges" is an array so "->>" doesn't do anything useful.
>
> The OP needs to use "json_array_elements" to navigate past the array and
> get to the next layer of the json where ->>'Name' will then work.
>
>
Thank you David. I had tried that function without much luck. But with
your inspiration, I made progress and got to this:

select
_message_exchange_id,jsonb_array_elements(_message_body->'Charges')->>'Name'
FROM message_import_court_case WHERE _message_exchange_id = 1296;
_message_exchange_id | ?column?
----------------------+--------------------------------------------
1296 | Possession Of Burglary Tools
1296 | Burglary In The Second Degree (Commercial)
(2 rows)

But what I really want is one line per message, with the charges in an
array. I can't seem to find the right syntax to make this work:

=> select
_message_exchange_id,array_agg(jsonb_array_elements(_message_body->'Charges')->>'Name')
FROM message_import_court_case WHERE _message_exchange_id = 1296;
ERROR: column "message_import_court_case._message_exchange_id" must appear
in the GROUP BY clause or be used in an aggregate function
LINE 1: select _message_exchange_id,array_agg(jsonb_array_elements(_...
^

=> select
_message_exchange_id,array_agg(jsonb_array_elements(_message_body->'Charges')->>'Name')
FROM message_import_court_case WHERE _message_exchange_id = 1296 GROUP BY 1;
ERROR: set-valued function called in context that cannot accept a set

=> select _message_exchange_id,(SELECT
array_agg(jsonb_array_elements(_message_body->'Charges')->>'Name')) FROM
message_import_court_case WHERE _message_exchange_id = 1296 GROUP BY 1;
ERROR: set-valued function called in context that cannot accept a set

=> select _message_exchange_id,(SELECT
array_agg(jsonb_array_elements(_message_body->'Charges')->>'Name')) FROM
message_import_court_case WHERE _message_exchange_id = 1296;
ERROR: column "message_import_court_case._message_exchange_id" must appear
in the GROUP BY clause or be used in an aggregate function
LINE 1: select _message_exchange_id,(SELECT array_agg(jsonb_array_el...

Thanks!

Ken

--
AGENCY Software
A Free Software data system
By and for non-profits
*http://agency-software.org/ <http://agency-software.org/>*
*https://demo.agency-software.org/client
<https://demo.agency-software.org/client>*
ken(dot)tanzer(at)agency-software(dot)org
(253) 245-3801

Subscribe to the mailing list
<agency-general-request(at)lists(dot)sourceforge(dot)net?body=subscribe> to
learn more about AGENCY or
follow the discussion.