How to create custom entity operator?

[leon]

akitas entity service has a .move function which simply moves the id from once place in the ids array to another.
but this is missing in elf.

It wasn't very hard to port over.
But I'm having some troubles with elf entities not exporting BaseEntityOptions and defaultEntitiesRef

import { Reducer } from '@ngneat/elf'
import { DefaultEntitiesRef, EntitiesRef, EntitiesState } from '@ngneat/elf-entities'
import { BaseEntityOptions, defaultEntitiesRef } from '@ngneat/elf-entities/lib/entity.state' // does not work

/**
 *
 * Move entity
 *
 * @example
 *
 * store.update(moveEntity(2, 3))
 *
 */
export function moveEntity<
  S extends EntitiesState<Ref>,
  Ref extends EntitiesRef = DefaultEntitiesRef,
>(fromIndex: number, toIndex: number, options: BaseEntityOptions<Ref> = {}): Reducer<S> {
  return function (state, context) {
    const { ref: { idsKey, entitiesKey } = defaultEntitiesRef } = options

    const ids = state[idsKey].slice()
    ids.splice(toIndex < 0 ? ids.length + toIndex : toIndex, 0, ids.splice(fromIndex, 1)[0])

    return {
      ...state,
      [entitiesKey]: [...state[entitiesKey]],
      [idsKey]: ids,
    }
  }
}

is there a better way to do a custom operator?
or do we simply need to export these also?

[NetanelBasal]

@leon, you can create a PR for this operator. It's tree-shakable, so I don't mind having it built-in.

[NetanelBasal]

Consider a readable approach - moveEntity({ fromIndex: 2, toIndex: 3 })