Update all values for given key nested in JSON array of objects

Question

I have a jsonb column data in a Postgres table my_table. It contains the following data:

[
   {"id":"1","status":"test status1","updatedAt":"1571145003"},
   {"id":"2","status":"test status2","updatedAt":"1571145323"}
]

I want to update the updatedAt key of all objects in that array using one query. I tried:

update my_table set data = data || '{"updatedAt": "1571150000"}';

The above query added a new object within the array like the following:

[
   {"id":"1","status":"test status1","updatedAt":"1571145003"},
   {"id":"2","status":"test status2","updatedAt":"1571145323"},
   {"updatedAt":"1571150000"}
]

I want the output like:

[
   {"id":"1","status":"test status1","updatedAt":"1571150000"},
   {"id":"2","status":"test status2","updatedAt":"1571150000"}
]

I also tried jsonb_set(), but that needs the second parameter to be the array index. I can't be sure of the count of JSON objects in the array.

If this can be solved with custom functions, also fine.

Answer 1

First cte unnest all elements of the array, second one update each element and then simply update the original table building the array again.

with ct as
(
    select id, jsonb_array_elements(data) dt
    from   t
)
, ct2 as
(
  select id, jsonb_set(dt, '{updatedAt}', '"1571150000"', false) dt2
  from   ct
)
update t
set    data = (select jsonb_agg(dt2) from ct2 where ct2.id = t.id);

select * from t;

id | data                                                                                                                                
-: | :-----------------------------------------------------------------------------------------------------------------------------------
 1 | [{"id": "1", "status": "test status1", "updatedAt": "1571150000"}, {"id": "2", "status": "test status2", "updatedAt": "1571150000"}]

db<>fiddle here

Answer 2

You declared Postgres 10, for which McNets has provided a valid solution. It should be a bit more efficient without CTEs as those cannot be inlined before Postgres 12:

UPDATE tbl
SET    data = (
   SELECT jsonb_agg(jsonb_set(d, '{updatedAt}', '"15711500000"', false))
   FROM   jsonb_array_elements(data) d
   );

However, still pretty inefficient while not all (or most) rows actually need an update. All rows are updated - as demonstrated in this fiddle with extended test case:

db<>fiddle here

If only a (small) part of all rows actually needs an update, it's much more efficient to update only those. Or, better yet, identify those rows with index support a priori. The first part is tedious and the second part not trivial in Postgres 10 (would require a specialized expression index).

Both has become much simpler and more efficient in Postgres 12 with the SQL/JSON path language:

UPDATE tbl
SET    data = (
   SELECT jsonb_agg(jsonb_set(dt, '{updatedAt}', '"15711500000"', false))
   FROM   jsonb_array_elements(data) dt
   )
WHERE  data @? '$.updatedAt ? (@ != "1571150000")';

The added WHERE data @? '$.updatedAt ? (@ != "1571150000")' basically says:

'Look at the key "updatedAt" (in all array elements) at the top level and check whether any of them is not equal to "1571150000"; return true if (and only if) such a key is found.'

Most importantly, this eliminates non-qualifying rows from the UPDATE early. See:

db<>fiddle here

It also can use indexes. The manual:

Also, GIN index supports @@ and @? operators, which perform jsonpath matching.

But index support is limited in this particular case because != is much harder to support than ==.