autoUpdate sets timestamp on both Creation and Update

[diego-sepulveda-lavin]

Package version

21.6.1

Describe the bug

Hi,
I'm observing unexpected behavior with the @column.dateTime decorator in Lucid, specifically with the autoUpdate option. Currently, a column with autoUpdate: true sets the timestamp not only on updates but also on creation, which may not align with the expected behavior.

Expected Behavior
autoCreate: true -> Sets the timestamp on row creation.

autoUpdate: true -> Sets the timestamp only on row updates, not on creation unless combined with autoCreate: true.

Actual Behavior
A column with autoUpdate: true (and no autoCreate) sets the timestamp on both creation and updates.

Details
The behavior stems from the initiateAutoCreateColumns method in src/Orm/BaseModel/index.ts, which checks column.meta.autoCreate || column.meta.autoUpdate when setting timestamps on creation. This causes autoUpdate: true to trigger timestamp setting during creation, which I suspect might be unintended.

Reproduction

import { DateTime } from 'luxon'
import { BaseModel, column } from '@adonisjs/lucid/orm'

export default class Post extends BaseModel {
  @column({ isPrimary: true })
  public id: number

  @column.dateTime({ autoCreate: true })
  public createdAt: DateTime

  @column.dateTime({ autoUpdate: true })
  public updatedAt: DateTime 
}

const post = new Post()
await post.save() // Both createdAt and updatedAt are set
post.title = 'New Title'
await post.save() // updatedAt is updated (expected)

Is This a Bug or Intended?
I'm unsure if this is a bug or intended design. The documentation suggests autoUpdate is for updates, but the current behavior (setting timestamps on both creation and updates) can be achieved by combining autoCreate: true and autoUpdate: true. If autoUpdate is meant to only affect updates, the || column.meta.autoUpdate condition in initiateAutoCreateColumns should be removed.
Additionally, this behavior makes autoUpdate: true impractical for columns that can remain null when no update has occurred, requiring a model hook workaround 👇

@column.dateTime() // no autoUpdate:true here
public updatedAt: DateTime | null

@beforeUpdate()
  public static setUpdatedAtOnUpdate(model: Post) {
    if (model.$isDirty) {
      model.updatedAt = DateTime.local()
    }
  }

Potential Breaking Change
Changing this behavior could be a breaking change for codebases relying on autoUpdate: true to set timestamps on both creation and updates. Such projects would need to update their decorators to use autoCreate: true, autoUpdate: true to maintain the current behavior.

Suggested Fix
If this is a bug, update initiateAutoCreateColumns to check only column.meta.autoCreate:

Please confirm if this is intended or a bug, and whether a fix would be considered. Happy to provide more details or assist with testing!

Reproduction repo

No response

[Th3C0deWizard]

Hey, I'm facing the same issue here. Did u find a workaround to this issue that does not involve the use of a hook to update? (I think its kind of ugly)

[diego-sepulveda-lavin]

Hey, I'm facing the same issue here. Did u find a workaround to this issue that does not involve the use of a hook to update? (I think its kind of ugly)

No, I haven't found another workaround different to invoking the hook. Maybe @thetutlage could give us some feedback

[diego-sepulveda-lavin]

Digging deeper a found a discord thread about this. On the topic they also mention a link to the laravel docs with the following:

When we call the save method, a record will be inserted into the database. The model's created_at and updated_at timestamps will automatically be set when the save method is called, so there is no need to set them manually.

With that description it might appear that current lucid functionality works as intended (IMHO inserts should not set updated_at), unfortunately I'm not familiar with Eloquent.

[Th3C0deWizard]

Yeah, I also think updated_at must be nullable to easily know when a record have not been touched