Re: express composite type literal as text

On 02/22/2015 10:07 AM, Eric Hanson wrote:
> Hi,
>
> How do I express a composite type literal as text?
>
> I'm trying to use a composite type in a WHERE clause. The examples in
> the docs
>
> http://www.postgresql.org/docs/9.4/static/rowtypes.html
>
> say:
>
> CREATE TYPE complex AS (
> r double precision,
> i double precision
> );
>
> CREATE TYPE inventory_item AS (
> name text,
> supplier_id integer,
> price numeric
> );
>
> CREATE TABLE on_hand (
> item inventory_item,
> count integer
> );
>
> INSERT INTO on_hand VALUES (ROW('fuzzy dice', 42, 1.99), 1000);
>
>
> Now I want to query for that row, specifying the item in the WHERE
> clause. I can't use the ROW() notation, because all values need to be
> represented as text over a REST api. But I can't seem to get the
> text-based syntax to work:
>
> select * from on_hand where item='("fuzzy dice",42,1.99)';
>
> yeilds
>
> ERROR: input of anonymous composite types is not implemented
>
> I've tried various forms of quote escaping and dollar quoting as the
> docs suggest, but they all produce that same error:
>
> select * from on_hand where item='(\\\"fuzzy dice\\\",42,1.99)';
> select * from on_hand where item=$$("fuzzy dice",42,1.99)$$;

From here:

http://www.postgresql.org/docs/9.3/static/sql-expressions.html

4.2.13. Row Constructors

So,

test=> INSERT INTO on_hand VALUES (ROW('bobble dog', 42, 5.99), 1000);
INSERT 0 1

test=> select * from on_hand ;
item | count
------------------------+-------
("fuzzy dice",42,1.99) | 1000
("bobble dog",42,5.99) | 1000
(2 rows)

test=> select * from on_hand where item = '("fuzzy dice",42,1.99)'::inventory_item;

item | count
------------------------+-------
("fuzzy dice",42,1.99) | 1000
(1 row)

>
>
> Thanks,
> Eric

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com