Delete value from nested json - postgres - json

Question

I have the json block modeled below. I want to selectively delete individual blocks from my_items based on the id which is AAA and BBB in my sample. ie if I tried to delete the AAA block under my_items I would want tojust delete the {"id" : "AAA"} but if wanted to delete the BBB block it would delete the larger {"name" : "TestRZ", "id" : "BBB", "description" : ""} block.
I know I can use the #- to remove whole blocks like SELECT '{sample_json}'::jsonb #- '{my_items}' would purge out the whole my_items block. But I dont know how to use this to conditionally delete children under a parent block of json. I have also used code similar to this example to append data inside a nested structure by reading in the node of the nested structure cat-ing new data to it and rewriting it. UPDATE data SET value= jsonb_set(value, '{my_items}', value->'items' || (:'json_to_adds'), true) where id='testnofeed'.
But I dont know how to apply either of these methods to: 1)Delete data in nested structure using #- or 2)Do the same using `jsonb_set. Anyone have any guidance for how to do this using either of these(or another method).
{
"urlName" : "testurl",
"countryside" : "",
"description" : "",
"my_items" : [
{
"id" : "AAA"
},
{
"name" : "TestRZ",
"id" : "BBB",
"description" : ""
},
],
"name" : "TheName"
}
Data is stored in value jsonb. when I update I will be able to pass in a unique kind so that it only updates this json in one row in db.
-- Table Definition
CREATE TABLE "public"."data" (
"id" varchar(100) NOT NULL,
"kind" varchar(100) NOT NULL,
"revision" int4 NOT NULL,
"value" jsonb
);

Answer 1

This works in PostgreSQL 12 and later with jsonpath support. If you do not have jsonpath, then please leave a comment.
with data as (
select '{
"urlName" : "testurl",
"countryside" : "",
"description" : "",
"my_items" : [
{
"id" : "AAA"
},
{
"name" : "TestRZ",
"id" : "BBB",
"description" : ""
}
],
"name" : "TheName"
}'::jsonb as stuff
)
select jsonb_set(stuff, '{my_items}',
jsonb_path_query_array(stuff->'my_items', '$ ? (#."id" <> "AAA")'))
from data;
jsonb_set
---------------------------------------------------------------------------------------------------------------------------------------------------
{"name": "TheName", "urlName": "testurl", "my_items": [{"id": "BBB", "name": "TestRZ", "description": ""}], "countryside": "", "description": ""}
(1 row)
To update the table directly, the statement would be:
update data
set value = jsonb_set(value, '{my_items}',
jsonb_path_query_array(value->'my_items',
'$ ? (#."id" <> "AAA")'));
This works for versions before PostgreSQL 12:
with data as (
select 1 as id, '{
"urlName" : "testurl",
"countryside" : "",
"description" : "",
"my_items" : [
{
"id" : "AAA"
},
{
"name" : "TestRZ",
"id" : "BBB",
"description" : ""
}
],
"name" : "TheName"
}'::jsonb as stuff
), expand as (
select d.id, d.stuff, e.item, e.rn
from data d
cross join lateral jsonb_array_elements(stuff->'my_items') with ordinality as e(item, rn)
)
select id, jsonb_set(stuff, '{my_items}', jsonb_agg(item order by rn)) as new_stuff
from expand
where item->>'id' != 'AAA'
group by id, stuff;
id | new_stuff
----+---------------------------------------------------------------------------------------------------------------------------------------------------
1 | {"name": "TheName", "urlName": "testurl", "my_items": [{"id": "BBB", "name": "TestRZ", "description": ""}], "countryside": "", "description": ""}
(1 row)
The direct update for this is a little more involved:
with expand as (
select d.id, d.value, e.item, e.rn
from data d
cross join lateral jsonb_array_elements(value->'my_items')
with ordinality as e(item, rn)
), agg as (
select id, jsonb_set(value, '{my_items}', jsonb_agg(item order by rn)) as new_value
from expand
where item->>'id' != 'AAA'
group by id, value
)
update data
set value = agg.new_value
from agg
where agg.id = data.id;