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Thread: Custom type literal conversion

Custom type literal conversion

From
Chris Bandy
Date:
I would like to create a new type for version strings that sorts numerically. The composite type below was quick to write and does not require superuser privileges. However, it doesn't respond to type casts the way I'd like.

Is there a way to implement this type's literal conversion without resorting to a base type?

Thanks
-- Chris

===

=> CREATE TYPE myversion AS (version integer[], build varchar);
CREATE TYPE
=> CREATE OR REPLACE FUNCTION myversion(text)
-> RETURNS myversion AS $$
$>     SELECT
$>         string_to_array(split_part($1, '+', 1), '.')::integer[],
$>         split_part($1, '+', 2);
$> $$ LANGUAGE SQL IMMUTABLE STRICT;
CREATE FUNCTION
=> SELECT myversion('1.0.9+jenkins');
      myversion      
---------------------
 ("{1,0,9}",jenkins)
(1 row)

=> SELECT '1.0.9+jenkins'::myversion;
ERROR:  malformed record literal: "1.0.9+jenkins"
LINE 1: SELECT '1.0.9+jenkins'::myversion;
               ^
DETAIL:  Missing left parenthesis.

Re: Custom type literal conversion

From
hubert depesz lubaczewski
Date:
On Wed, Sep 24, 2014 at 2:45 PM, Chris Bandy <bandy.chris@gmail.com> wrote:
I would like to create a new type for version strings that sorts numerically. The composite type below was quick to write and does not require superuser privileges. However, it doesn't respond to type casts the way I'd like.

Is there a way to implement this type's literal conversion without resorting to a base type?

I think you need to define casts too, but in any way - check if "semver" extension (available on pgxn) doesn't solve your problem.

depesz

Re: Custom type literal conversion

From
Chris Bandy
Date:
On Wed, Sep 24, 2014 at 8:40 AM, hubert depesz lubaczewski <depesz@gmail.com> wrote:
On Wed, Sep 24, 2014 at 2:45 PM, Chris Bandy <bandy.chris@gmail.com> wrote:
I would like to create a new type for version strings that sorts numerically. The composite type below was quick to write and does not require superuser privileges. However, it doesn't respond to type casts the way I'd like.

Is there a way to implement this type's literal conversion without resorting to a base type?

I think you need to define casts too, but in any way - check if "semver" extension (available on pgxn) doesn't solve your problem.


Casts from what? The following is not sufficient:

=> CREATE CAST (unknown AS myversion) WITH FUNCTION myversion(unknown);
CREATE CAST
=> SELECT '1.0.9+jenkins'::myversion;
ERROR:  malformed record literal: "1.0.9+jenkins"

And cast on "record" isn't valid:

=> CREATE CAST (record AS myversion) WITH FUNCTION myversion(unknown);
ERROR:  source data type record is a pseudo-type

I know about the semver extension, but I'm interested in a solution that does not require extension/superuser access.

Thanks
-- Chris