Projection

Which fields a query returns, as field paths mapped to a flag.

• { name: 1, "address.city": 1 } returns only those fields (and _id).
• { passwordHash: 0 } returns everything except those fields.
• _id is returned unless it is set to 0, and it is the one field that may differ from the rest: { name: 1, _id: 0 } is valid.
• Inclusion and exclusion cannot be mixed for any other field.

Pass the projection inline, or declare it as const, so the result type can be worked out from it.