prisma-field-is-null-or-undefined.md

In a book rental app, to query a book that isn't returned yet (returnedAt is either null or undefined):

const rented = await this.db.rental.findFirst({
  where: {
    book: {
      uuid: params.id,
    },
    OR: [
      {
        returnedAt: null,
      },
      {
        returnedAt: {
          isSet: false,
        },
      },
    ],
  },
})