| From: | Maciej Szopinski <maciej(dot)sz(at)gmail(dot)com> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Is there a way to address all elements of JSON array when creating a constraint in PosgreSQL? |
| Date: | 2014-01-21 09:34:43 |
| Message-ID: | CACYP-QPiPfgGz6U_Q87p4fwkiFP9JOx6h9T0e4zsXZi8QD2wTA@mail.gmail.com |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Hello,
Does PostgreSQL provide any notation/method for putting a constraint on
each element of a JSON array?
An example to illustrate:
create table orders(data json);
insert into orders values ('
{
"order_id": 45,
"products": [
{
"product_id": 1,
"name": "Book"
},
{
"product_id": 2,
"name": "Painting"
}
]
}
');
I can easily add a constraint on the order_id field:
alter table orders add check ((data->>'order_id')::integer >= 1);
Now I need to do the same with product_id. I can put constraint on
idividual array items:
alter table orders add check ((data->'products'->0->>'product_id')::integer
>= 1);
alter table orders add check ((data->'products'->1->>'product_id')::integer
>= 1);
-- etc.
So what I'm looking for is some kind of wildcard operator for matching any
JSON array element:
alter table orders add check ((data->'products'->*->>'product_id')::integer
>= 1);
-- ^ like this
I know that this can be done by extracting products to a separate table
with a foreign key to orders. But I want to know if this is possible within
single JSON column, so I can keep that in mind when designing a database
schema.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Stefan Warten | 2014-01-21 13:42:09 | pg_upgrade fails: "Mismatch of relation OID in database" - 9.2.4 to 9.3.2 |
| Previous Message | Albe Laurenz | 2014-01-21 08:46:24 | Re: to_date() and invalid dates |