Postgres SELECT where the WHERE is UUID or string

Question

I have the following simplified table in Postgres:

• User Model
  • id (UUID)
  • uid (varchar)
  • name (varchar)

Answer 1

You could check with a regular expression:

SELECT *
FROM user
WHERE ('jsdfhiureeirh' ~ E'^[[:xdigit:]]{8}-([[:xdigit:]]{4}-){3}[[:xdigit:]]{12}$'
       AND id = 'jsdfhiureeirh')
      OR uid = 'jsdfhiureeirh';

Answer 2

I had originally misunderstood the question. If you want to "safely" try to cast a string to a UUID, you can write a function to catch the invalid_text_representation exception and just return null (modified from an answer to a different question):

CREATE OR REPLACE FUNCTION uuid_or_null(str text)
RETURNS uuid AS $$
BEGIN
  RETURN str::uuid;
EXCEPTION WHEN invalid_text_representation THEN
  RETURN NULL;
END;
$$ LANGUAGE plpgsql;

SELECT uuid_or_null('INVALID') IS NULL will then result in true.

In other words (given that (true or null) = true),

SELECT * FROM user
WHERE id = uuid_or_null('FOOBARBAZ') OR uid = 'FOOBARBAZ';

---

Original answer:

Postgres will automatically convert the string to a UUID for you, but you need to use a valid UUID. For example:

SELECT * FROM user
WHERE id = '5af75c52-cb8e-44fb-93c8-1d46da518ee6' or uid = 'jsdfhiureeirh';

You can also let Postgres generate UUIDs for you using a DEFAULT clause with the uuid_generate_v4() function by using the uuid-ossp extension:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

CREATE TABLE user (  
   id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
   uid TEXT,
   name TEXT
);

Answer 3

Found it! Casting the UUID column to ::text stops the error. Not sure about the performance hit but on about 5000 rows I get more than adequate performance.

SELECT * FROM user
WHERE id::text = 'jsdfhiureeirh' OR uid = 'jsdfhiureeirh';

SELECT * FROM user
WHERE id::text = '33bb9554-c616-42e6-a9c6-88d3bba4221c' 
  OR uid = '33bb9554-c616-42e6-a9c6-88d3bba4221c';