Postgresql: Remove Attribute from JSON Column

PostgreSQL: Remove attribute from JSON column

Update: for 9.5+, there are explicit operators you can use with jsonb (if you have a json typed column, you can use casts to apply a modification):

Deleting a key (or an index) from a JSON object (or, from an array) can be done with the - operator:

SELECT jsonb '{"a":1,"b":2}' - 'a', -- will yield jsonb '{"b":2}'
       jsonb '["a",1,"b",2]' - 1    -- will yield jsonb '["a","b",2]'

Deleting, from deep in a JSON hierarchy can be done with the #- operator:

SELECT '{"a":[null,{"b":[3.14]}]}' #- '{a,1,b,0}'
-- will yield jsonb '{"a":[null,{"b":[]}]}'

For 9.4, you can use a modified version of the original answer (below), but instead of aggregating a JSON string, you can aggregate into a json object directly with json_object_agg().

Related: other JSON manipulations whithin PostgreSQL:

• How do I modify fields inside the new PostgreSQL JSON datatype?

Original answer (applies to PostgreSQL 9.3):

If you have at least PostgreSQL 9.3, you can split your object into pairs with json_each() and filter your unwanted fields, then build up the json again manually. Something like:

SELECT data::text::json AS before,
       ('{' || array_to_string(array_agg(to_json(l.key) || ':' || l.value), ',') || '}')::json AS after
FROM (VALUES ('{"attrA":1,"attrB":true,"attrC":["a","b","c"]}'::json)) AS v(data),
LATERAL (SELECT * FROM json_each(data) WHERE "key" <> 'attrB') AS l
GROUP BY data::text

With 9.2 (or lower) it is not possible.

Edit:

A more convenient form is to create a function, which can remove any number of attributes in a json field:

Edit 2: string_agg() is less expensive than array_to_string(array_agg())

CREATE OR REPLACE FUNCTION "json_object_delete_keys"("json" json, VARIADIC "keys_to_delete" TEXT[])
  RETURNS json
  LANGUAGE sql
  IMMUTABLE
  STRICT
AS $function$
SELECT COALESCE(
  (SELECT ('{' || string_agg(to_json("key") || ':' || "value", ',') || '}')
   FROM json_each("json")
   WHERE "key" <> ALL ("keys_to_delete")),
  '{}'
)::json
$function$;

With this function, all you need to do is to run the query below:

UPDATE my_table
SET data = json_object_delete_keys(data, 'attrB');

PostgreSQL - JSON column remove attribute inside an array

I've figure out what I needed to do.

SELECT jsonb_array_elements(jsonb '[{"a":1, "b":2}, {"a":3, "b":4}]') - 'b';

Output

{"a": 1}
{"a": 3}

Postgres - Deleting attributes inside json object of json column

Just replace vendor with an empty value by appending it.

update table_name 
  set data = data || '{"vendor": {}}'

This requires data to be defined as jsonb (which it should be). If it's not, you need to cast it: data::jsonb || ....

If you don't need the vendor key at all, you can also do:

update table_name 
  set data = data - 'vendor'

which completely removes the key from the value (so it results in {"footerText": "some_text", "headerText": "header_text"})

How to remove field from each elements json array postgres?

There is no operator or built-in function to do that. Unnest the array and aggregate modified elements in the way like this:

update items t
set data = (
    select jsonb_agg(elem- 'count')
    from items
    cross join lateral jsonb_array_elements(data) as arr(elem)
    where id = t.id)

Test it in db<>fiddle.

How to remove all JSON attributes with certain value in PostgreSQL

There is no built-inf function for this, but you can write your own:

create function remove_keys_by_value(p_input jsonb, p_value jsonb)
  returns jsonb
as
$$
  select jsonb_object_agg(t.key, t.value)
  from jsonb_each(p_input) as t(key, value)
  where value <> p_value;
$$
language sql
immutable;

Then you can do:

update records
  set payload = remove_key_by_value(payload, to_jsonb(3))
where parent = 1;

This assumes that payload is defined as jsonb (which it should be). If it's not, you have to cast it: payload::jsonb

Remove multiple keys from jsonb column in one statement

That should be as simple as applying the #- operator multiple times:

SELECT '{ "a": 1, "b": 2, "c": 3 }'::jsonb #- '{a}' #- '{b}';

 ?column? 
----------
 {"c": 3}
(1 row)

postgres remove json object from json array

demo:db<>fiddle

Why do you store JSON objects in text columns? In that case you need to cast it before using it as JSON:

SELECT
    id,
    json_agg(elems)                               -- 3
FROM mytable,
    json_array_elements(jsondata::json) as elems  -- 1
WHERE elems ->> 'id' <> 'app2'                    -- 2
GROUP BY id

1. Cast text into JSON; Extract the JSON array into a record per element
2. Filter the required objects
3. Reaggregate remaining elements into a new JSON array

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