Insert rule and default values for PK

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Insert rule and default values for PK

KÖPFERL Robert
Hi,

I've a prolem inserting records in a view using different ways.
I want to insert either way, with PK given and without PK which should then
be taken by its DEFAULT stanza:
insert into a_and_b(a) values (537)    # id not given, self assigned
insert into a_and_b(x) values (true)    # id not given, self assigned
insert into a_and_b(x,id) values (true,55)   # id given, take that

For this example I created two tables. Note the Serial at tbla:

CREATE TABLE tbla
(
 id int4 NOT NULL,
 a int4,
 b varchar(12), CONSTRAINT tbla_pk PRIMARY KEY (id)
)

CREATE TABLE tblb
(
 id int4 NOT NULL,
 x bool, y timestamp,
 CONSTRAINT tblb_pk PRIMARY KEY (id),
 CONSTRAINT tblb_fk FOREIGN KEY (id) REFERENCES tbla (id) ON UPDATE CASCADE
ON DELETE CASCADE
)

My view is defined as to concatinate this 1:1 relation:
CREATE OR REPLACE VIEW a_and_b AS
 SELECT tbla.id, tbla.a, tbla.b, tblb.x, tblb.y
   FROM tbla NATURAL LEFT OUTER JOIN tblb;




In the first run I tried this insert rule. But it turned out that I can't
insert rows, if I omit id
CREATE OR REPLACE RULE a_b_insert AS
    ON INSERT TO a_and_b DO INSTEAD (
    INSERT INTO tbla (id, a, b) VALUES (new.id, new.a, new.b);
    INSERT INTO tblb (id, x, y) VALUES (new.id, new.x, new.y););


So I had a try with that rule which already does what was intended. I can
now choose of wheter I want to supply id of if not.
However I get disturbed by the 'nextval' and 'curval'-functions. This is
redundant with the tables definition. I don't like that.
The other way round, leave all id out, helps for tbla (since a default is
defined) but leaves tblb alone:

CREATE OR REPLACE RULE a_b_insert AS
    ON INSERT TO a_and_b DO INSTEAD ( INSERT INTO tbla (id, a, b)
  VALUES (coalesce(new.id,nextval('public.tbla_id_seq'::text)), new.a,
new.b);
 INSERT INTO tblb (id, x, y)
  VALUES (coalesce(new.id,currval('public.tbla_id_seq'::text)), new.x,
new.y);
);



What would you do? What is the postgres way of solving this problem.

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