Hibernate UNIQUE INDEX 的注解映射（约束）

Question

CREATE TABLE image_info
(
    id BIGSERIAL PRIMARY KEY,
    is_main boolean,
    image_id BIGINT REFERENCES image(id) NOT NULL,
    good_id BIGINT REFERENCES good(id) NOT NULL
);

I need to add a constraint that only unique good_id must have one is_main = true, but many is_main = false for example:

INSERT INTO image_info (is_main, good_id, image_id) VALUES (true, 2,1);
INSERT INTO image_info (is_main, good_id, image_id) VALUES (false, 2,2);
INSERT INTO image_info (is_main, good_id, image_id) VALUES (false, 3,1);
INSERT INTO image_info (is_main, good_id, image_id) VALUES (true, 3,2);
INSERT INTO image_info (is_main, good_id, image_id) VALUES (false, 3,3);
INSERT INTO image_info (is_main, good_id, image_id) VALUES (true, 3,4); // - error because of constraint

I can add this constraint via SQL script:

CREATE UNIQUE INDEX "only_one_good_with_is_main_true_uix" ON image_info(good_id) WHERE is_main = true;

My question is how can I add the same constraint with hibernate mapping?

Answer 1

You can't do that with plain Hibernate annotations. You should use a schema management tool like Liquibase or Flyway anyway, as Hibernate is not meant to be used for schema migration or these database specific things.