How to create one-to-one relation?

[pikhovkin]

No description provided.

[loicknuchel]

Hi @pikhovkin
We don't support defining the relation type as we try to be close to what is the database structure.
Yet, we discussed in #166 the possibility to show relations as one-to-one when they meet the criteria (link to a unique column).
Still not done yet but it's on our list.
What do you think about it?

[michi-zuri]

Hey @loicknuchel,

I was confused^1 by the criteria you mentioned above and probably misunderstood what you meant with link to a unique column. As I may not be the only person, here's a how I would name the criteria for showing a one-to-one relation:

• foreign key constraint defined on/placed on/attached to a unique column^2
  or
• link from a unique column^2

Would you agree? I'm sorry, I haven't gotten around to contribute any code to azimutt yet. It's on my bucket list of things to do before I die, but I have no idea when that will be. Keep up the great work!

^1: because foreign key constraints must point to a unique column^2, otherwise it's not a foreign key.
^2: or a unique column group enforced by a composite unique constraint

[loicknuchel]

Hi @michi-zuri

You're right, I wrote too quickly, it's not a "link to a unique column" but a foreign key with a unique constraint.
In fact, both side of the relation should have a unique constraint, but it's often the case for the target as we link to primary keys ^^
On the "unique column group", you are right, but for now Azimutt handles composite unique constraints but not composite foreign keys (big refacto in the data model for this ^^).

Don't worry about your contribution ;)
You can do it when you have time and you can ping me if you need some help to get started.
++