How to update JSONB array based on property name? - json

Question

I would like to update fields of the following JSON array (stored in a column with JSONB datatype) based on the objectId.
[
{
objectId: 'gDKn1jM5d',
objectType: 'type1',
posX: 50,
posY: 100,
},
{
objectId: '4dg5E8BDv',
objectType: 'type2',
posX: 50,
posY: 100,
},
{
objectId: 'ZmCwOf5N2',
objectType: 'type3',
posX: 100,
posY: 150,
}
]
In Mongodb I can use a simple update statement but I was not able to find a way in postgres.
For example I would like to update all array elements with objectId 'ZmCwOf5N2' to the posX value 300 (that means it would only affect the 3rd array item).
I'm looking for a plain SQL statement in order to execute the update.
The postgres version is 11.
It is not possible for me to install extensions because I'm using a database as a service provider. However, in case there is no easy way to accomplish the update statement, I would be able to add a postgres function using e.g. C code.

Answer 1

UPDATE tbl t
SET js =
(
SELECT jsonb_agg(CASE WHEN elem->>'objectId' = 'ZmCwOf5N2'
THEN jsonb_set(elem, '{posX}', to_jsonb(int '300'))
ELSE elem
END) AS js1
FROM jsonb_array_elements(t.js) elem
)
WHERE t.js #> '[{"objectId": "ZmCwOf5N2"}]';
Note that this ..
adds the 'posX' key if it's missing
updates rows even where nothing changes
To only update existing keys and only update the row if the update actually changes the value:
UPDATE tbl t
SET js =
(
SELECT jsonb_agg(CASE WHEN elem->>'objectId' = 'ZmCwOf5N2'
THEN jsonb_set(elem, '{posX}', to_jsonb(int '300'), false) -- !
ELSE elem
END) AS js1
FROM jsonb_array_elements(t.js) elem
)
WHERE t.js #> '[{"objectId": "ZmCwOf5N2"}]'
AND js <>
(
SELECT jsonb_agg(CASE WHEN elem->>'objectId' = 'ZmCwOf5N2'
THEN jsonb_set(elem, '{posX}', to_jsonb(int '300'), false)
ELSE elem
END) AS js1
FROM jsonb_array_elements(t.js) elem
); --!
See:
How to update complex jsonb column?
Update key value in jsonb array of objects