Payload field hooks run per-field, not per-document

In most CMSs, hooks live on the whole document. In Payload, a hook lives on a specific field and receives that field's context — siblingData, value, operation:

{
  name: 'slug',
  type: 'text',
  hooks: {
    beforeChange: [
      ({ value, siblingData, operation }) => {
        if (operation === 'create' && !value) {
          return slugify(siblingData.title) // compute the slug from a sibling field
        }
        return value
      },
    ],
  },
}

Combine that with virtual: true and you get purely computed fields: the hook produces the value on afterRead, and nothing ever lands in the database.

It's a small shift in mental model, but it makes logic local to the data it touches instead of scattered across one giant document-level hook.