Best way to generate null form values for a Prisma update

model Foo {
  id String @id @default(uuid(7))
  bar String? 
}

export const updateFoo: UpdateFoo<{
  id: string;
  bar?: string;
}, Foo> = async ({ id, ...updatedData }, context) => {

  if (!context.user) {
    throw new HttpError(401, 'Not authorized');
  }

  const updated = await context.entities.Foo.update({
    where: { 
      id,
    },
    data: {
      updatedData,
    }
  });

formSchema = z
  .object({
    title: z.string().optional().nullable()
})

{
  bar: undefined
}