Feature: Define relationships in config

[nhuysamen-godaddy]

This is probably a non-starter, but it would be great (albeit probably error-prone), to be able to specify relationships in config rather than relying on foreign keys. This would allow you to use sqlboiler with platform like PlanetScale that does not support foreign keys.

[stephenafamo]

This sounds interesting. If you can create a PR for this feature, I'll be happy to review it.

[tanaka-takuto]

I was just about to use SQLBoiler with PlanetScale! I had no choice but to try to use it without foreign key constraints (no relations). This is a long awaited feature!

[Rosswell]

imo this would be a nice feature in dbs with foreign keys as well, as afaict the reverse relationship is auto-derived, and cannot be renamed through a toml config, because the foreign key only exists on one of the tables

[stephenafamo]

@Rosswell I believe it is possible to alias the reverse relationship using the foreign property.

Regardless, I agree that the ability to manually define relationships would be quite useful. If only to create some "convenient" relationships that you don't necessarily need to be enforced by the DB.

[chrisngyn]

@stephenafamo Could you review this PR above?

[adsteel]

Would love to see this as well. Not being able to add non-FK columns to a join table is another limitation this would help to remove.

[stephenafamo]

Implemented in #1282