Sortable

The @Sortable decorator enables your model to automatically sort on a particular field withiin your model. Typically, when doing this, you will also want to apply a scope, which enables the sorting to apply only to those records matching the scope.

export default class TodoItem extends ApplicationModel {
  @Sortable({ scope: 'user' })
  public position: DreamColumn<EdgeNode, 'position'>

  @deco.BelongsTo('User')
  public user: User
}

Once this is applied, any time any records matching a scope receive changes to their position field, all other records matching that scope will automatically be shuffled around to maintain consistent order.

Unique constraint

It's a good idea to apply a unique constraint to the sortable column; however, Sortable is incompatible with unique indexes, so you need to add a deferrable unique constraint, instead.

import { Kysely } from 'kysely'
import { MigrationHelpers } from '@rvoh/dream'

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export async function up(db: Kysely<any>): Promise<void> {
  await MigrationHelpers.addDeferrableUniqueConstraint(
    'graph_edge_nodes_uniq_on_edge_id_node_id_position',
    'graph_edge_nodes',
    ['edge_id', 'node_id', 'position'],
    db,
  )
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export async function down(db: Kysely<any>): Promise<void> {
  await MigrationHelpers.dropConstraint(
    'graph_edge_nodes_uniq_on_edge_id_node_id_position',
    'graph_edge_nodes',
    db,
  )
}