Do you know a json_populate_record alternative method to create a ROW with a named field notation?
Hello,
In this example:
```
CREATE TYPE contact AS (
firstname VARCHAR,
lastname VARCHAR
);
postgres=# SELECT json_populate_record(NULL::contact,
postgres(# '{
postgres'# "firstname": "John",
postgres'# "lastname": "Doe"
postgres'# }'
postgres'# );
json_populate_record
----------------------
(John,Doe)
(1 row)
```
**Question:** do you know a method like json_populate_record (
https://www.postgresql.org/docs/13/functions-json.html), which allows
creating a `ROW` with named field notation without using a json format?
I know the `ROW` syntax expression:
```
postgres=# SELECT ROW('John', 'Doe')::contact;
row
------------
(John,Doe)
(1 row)
```
But I didn't find a `ROW` constructors (
https://www.postgresql.org/docs/13/sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS)
syntax allowing a named field notation.
Best regards,
Stéphane
--
Stéphane Klein <contact@stephane-klein.info>
Homepage: http://stephane-klein.info
=?UTF-8?Q?St=C3=A9phane_Klein?= <contact@stephane-klein.info> writes:
**Question:** do you know a method like json_populate_record (
https://www.postgresql.org/docs/13/functions-json.html), which allows
creating a `ROW` with named field notation without using a json format?
You mean you want to give the field names explicitly in the expression?
The closest thing I can think of is to make a constructor function and
invoke it with named-argument notation:
regression=# CREATE TYPE contact AS (
regression(# firstname VARCHAR,
regression(# lastname VARCHAR
regression(# );
CREATE TYPE
regression=# create function make_contact(firstname varchar, lastname varchar)
regression-# returns contact as 'select row(firstname, lastname)::contact'
regression-# language sql;
CREATE FUNCTION
regression=# select make_contact(firstname => 'John', lastname => 'Doe');
make_contact
--------------
(John,Doe)
(1 row)
A bit tedious to set up, but it would have some advantages, eg you
could provide default values.
regards, tom lane