How to create bidirectional (inverse) one-to-one relationships?

For example, let’s say I have a Person and a Passport tables. One person has only one passport and one passport belongs to one person.

schema.js

    tableSchema({
      name: "persons",
      columns: [
        { name: "passport_id", type: "string" },
        ...
      ]
    }),
    tableSchema({
      name: "passports",
      columns: [
        { name: "person_id", type: "string" },
        ...
      ]
    }),

Person.js

export default class Person extends Model {
  static table = "persons";

  @relation("passports", "passport_id") passport;
  ...
}

Passport.js

export default class Passport extends Model {
  static table = "passports";

  static associations = {
    persons: { type: "belongs_to", key: "person_id" }
  };
  @relation("persons", "person_id") person;
  ...
}

I create a new passport:

database.collections.get("passports").create(passport => {
  passport.person.set(person);
  // ...
});

However, I would like being able to access passport from person as well. Is manually updating person.passport the only way? With Realm I believe there is a way to it with linking objects properties.

[radex]

Perhaps it would be nice to have the @children equivalent for to-one relationships? (@child?)

Perhaps! TBH I’m not sure if to-one relations (as opposed to just single belongs_to relation) is idiomatic. Because you’re creating two sources of truth. If you have two objects that are supposed to point at each other, but one of them points at something else, it’s en error. It’s easier if just one of the objects points at the other (say, Passport points at Person). This way, say, Person, would only have a helper getter to find its Passport, based on a query.

Here’s an example of this:

  @lazy
  _currentUserQuery: Query<User> = this.collections
    .get(Tables.users)
    .query(Q.where(Columns.users.isMe, true))

  @lazy
  currentUser: Observable<User> = this._currentUserQuery.observe().pipe(
    switchMap(([user]) => {
      invariant(user, `No user marked as isMe=true found`)
      return user.observe()
    }),
  )

It would be nice if this could be minified to a single line, using a decorator. If you want to implement something to that point, let me know, and I can give you pointers as to how 😃

[cwagner22]

Perhaps it would be nice to have the @children equivalent for to-one relationships? (@child?)

I’ve found a way to access passport from person without having to set the id manually (to person) by adding this to the Person model:

  @lazy passport = this.collections
    .get("passports")
    .query(Q.where("person_id", this.id));

Unfortunately this returns an array of results so I have to do that in my code, which is quite ugly: const passport = this.props.passport[0];