How to use with/has/preload in v5

[yarapolana]

Hello there, I am converting my v4.1 project to v5 and I have some difficulties understanding and using the with, has, and preload relationships in v5.

Here is what I am trying to do and a reference to how I did these in v4.1
and my attempts in v5

Tried accessing this page but it goes back to the same introduction page
https://preview.adonisjs.com/guides/database/query-builder 👈🏽 loop

[yarapolana]

After many failed attempts preloading like this worked

 const user = await auth.authenticate()
 await user.preload('profile')
 return user

wondering why this comes out empty

 const user = await auth.user.preload('profile')

[thetutlage]

Preloading means, you load the relationship from the database and set it on the existing instance. Which means

await user.preload('profile')

// will set following without returning anything
user.profile

Preloading from a single model instance is not that useful. However, preloading is useful when you are fetching more than one rows and want to load relationships at the same time.

const users = await User.query().preload('profile')

// here all users will have the `profile` property
users.forEach((user) => {
  user.profile
})

However, when working with a single instance (as you are), you can do following.

const profile = await auth.user!.related('profile').query().first()

To summarize. To keep the behavior of preload consistent it never returns any value but instead set the relationship on the parent model instance. Hope this helps :)

Regarding with. It has been replaced with preload
The has method works as it used to work earlier

[yarapolana]

Wow @thetutlage didn't know you worked on sundays.
Thank you for the fast reply as usual.

For the has in the context of scopes it appears to only accept undefined

  public static hasRooms = scope(query => {
    return query.has('rooms') // <-- complains that "it is not assignable to parameter of type 'undefined'"
  })

My untested workaround was to use this

  public static hasRooms = scope(_ => {
    return Post.query().has('rooms')
  })

[thetutlage]

Yup. Since your questions are well constructed, there are usually easy to reply.

The scope helper has no knowledge (that static level) that you were dealing with the query builder of the Post model. It is a typescript limitation. So you have to define the scope as follows:

public static hasRooms = scope<typeof Post>(query => {
   query.has('rooms')
})

[yarapolana]

Thank you a thousand. =)
Enjoy the rest of the Sunday.