DAO on compound/multiple primary key ?

Hello,

PostgreSQL can use multiple fields as Primary Key (doc) but how to handle that with Exposed DAO ?

I tried to use the DAO with a table which is quite complexe. Because example is better than words. Here the SQL :

CREATE TABLE table__contacts_first
(
    contact_id    UUID         NOT NULL,
    app_id        VARCHAR(128) NOT NULL,

    --- other fields ...

    FOREIGN KEY (contact_id) REFERENCES table__contacts (contact_id),
    PRIMARY KEY (contact_id, app_id)
);

As you can see, the table__contacts_first doesn’t have any PK, but the pair contact_id + app_id acts as is. I have the following Exposed Table:

object ContactsFirstTable : Table(name = "table__contacts_first") {
    val contactId = reference("contact_id", ContactsTable).primaryKey()
    val appId = varchar("app_id", length = 128).primaryKey()
}

And now the Exposed DAO:

class ContactFirstDao(id: EntityID<UUID>) : UUIDEntity(id) {
    companion object : UUIDEntityClass<ContactFirstDao>(ContactsFirstTable)
}

Obviously, I got errors and in fact, I should construct my ContactFirstDao using contactId and appId.

Do you have any idea how I could achieve that ?

Thanks 👍

[rodrigogs]

So, no composite keys for Exposed?

I’m not calling it ORM anymore then. Composite keys are pretty basic!

[scorsi]

An amaizing library: SQL ! I stopped using libraries, ORMs, … Just SQL is enough. But you can take a look at Ktorm (https://ktorm.liuwj.me/).

I left that issue open because it’s an importante missing feature.