Updating JSON in postgres based on dynamic input of type json array - arrays

Question

I have a column in postgres table which is of JSON type and looks something like
{
"Name": "Some Name",
"Stages": [
{
"Title": "Early Flight",
"Tags": [....],
"Date": "2021-11-05T00:00:00",
"CloseDate": ""
},
{
"Title": "Midway Flight",
"Tags": [....],
"Date": "2021-11-05T00:00:00",
"CloseDate": ""
},
{
"Title": "Pro Flight",
"Tags": [....],
"Date": "2021-11-05T00:00:00",
"CloseDate": ""
},
{
"Title": "Expert Start",
"Tags": [....],
"Date": "2021-11-05T00:00:00",
"CloseDate": ""
}
]
}
I want to update the Date for the number of items that are provide in the newInputItem,
meaning the Date for Midway Flight and Expert Flight needs to change.
I tried using CTE as below but the query updates only the first element of the input array in this case its just Midway Flight that gets updated.
WITH newInputItem as
(
select
arr.newInputItem ::json ->> 'Title' as State,
(arr.newInputItem ::json ->> 'NewDate')::timestamp as NewDate
from
json_array_elements('[
{"Title" : "Midway Flight", "Date" : "01 / 01 / 1777"},
{"Title" : "Expert Flight", "Date" : "01 / 01 / 1999"}
]') WITH ORDINALITY arr(newInputItem, index)
),
oldItem AS
(
SELECT
('{Stages,' || index - 1 || ',"Date"}')::TEXT[] AS path,
user_id,
arr.oldItem ::json ->> 'Title' AS title
FROM
department.Process_Instance
jsonb_array_elements(process_instance_data -> 'Stages') WITH ORDINALITY arr(oldItem, index)
WHERE
department.Process_Instance."user_id" = 17
)
UPDATE
department.Process_Instance pi
SET
process_instance_data = jsonb_set(process_instance_data, oldItem.path, to_json(newInputItem.NewDate)::JSONB)
FROM
oldItem,
newInputItem
WHERE
pi.user_id = oldItem.user_id
AND oldItem.title = newInputItem.State;

Answer 1

In order to make several updates into the same jsonb data within the same query, you need to create an aggregate function based on the standard jsonb_set function :
CREATE OR REPLACE FUNCTION jsonb_set (x jsonb, y jsonb, p text[], z jsonb, b boolean)
RETURNS jsonb LANGUAGE sql IMMUTABLE AS
$$ SELECT jsonb_set (COALESCE(x, y), p, z, b) ; $$ ;
CREATE AGGREGATE jsonb_set_agg(jsonb, text[], jsonb, boolean)
( sfunc = jsonb_set, stype = jsonb) ;
Then, as you can't call an aggregate function directly in the SET clause of an UPDATE statement, you have to insert an additional cte before your UPDATE statement :
WITH newInputItem as
(
select
arr.newInputItem ::json ->> 'Title' as State,
(arr.newInputItem ::json ->> 'NewDate')::timestamp as NewDate
from
json_array_elements('[
{"Title" : "Midway Flight", "Date" : "01 / 01 / 1777"},
{"Title" : "Expert Flight", "Date" : "01 / 01 / 1999"}
]') WITH ORDINALITY arr(newInputItem, index)
), oldItem AS
(
SELECT
('{Stages,' || index - 1 || ',"Date"}')::TEXT[] AS path,
user_id,
arr.oldItem ::json ->> 'Title' AS title
FROM
department.Process_Instance
jsonb_array_elements(process_instance_data -> 'Stages') WITH ORDINALITY arr(oldItem, index)
WHERE
department.Process_Instance."user_id" = 17
), final AS
(
SELECT oldItem.user_id
, jsonb_set_agg( process_instance_data, oldItem.path,
to_json(newInputItem.NewDate)::JSONB, True) AS data_final
FROM oldItem
INNER JOIN newInputItem
ON oldItem.title = newInputItem.State
GROUP BY oldItem.user_id
)
UPDATE
department.Process_Instance pi
SET
process_instance_data = final.data_final
FROM
final
WHERE
pi.user_id = final.user_id ;