Tagged Support

[mhayes853]

Hi everyone. If you're like me, there's a decent chance that you're using Tagged for strongly typed IDs in your app. Currently, this library doesn't support Tagged, so I've made a rudimentary package you can use here that applies retroactive conformances on Tagged to all the necessary protocols that this library provides so you can use it in your schema types.

Thanks.

[mbrandonw]

Hi @mhayes853, thanks for sharing!

We also hope to leverage SPM's new traits system to be able to layer on conformances like this when both Tagged and StructuredQueries are used together. But we're not sure when we will get to that, and so your repo serves as a helpful reference for others!

[stephencelis]

We explored it here: #13. That said, if/when we merge it we should link to your repo as a pre-Swift 6.1 solution!

[jcmourey]

Thanks for this.

To make it easier to perform UUID-based Tagged ID queries with SharingGDRB, I added the following extensions:

extension Tagged where RawValue == UUID {
    public typealias Representation = Tagged<Tag, RawValue.BytesRepresentation>

    public var representation: Representation {
        let bytes = UUID.BytesRepresentation(queryOutput: rawValue)
        return Representation(bytes)
    }
}

which allows this:

@Table
struct SyncUp: Hashable, Identifiable, Equatable {
    typealias ID = Tagged<Self, UUID>

    @Column(as: ID.Representation.self)
    let id: ID
    var seconds: Int = 60 * 5
    var theme: Theme = .bubblegum
    var title = ""
}
extension SyncUp.Draft: Equatable {}

@Table
struct Attendee: Hashable, Identifiable {
    typealias ID = Tagged<Self, UUID>

    @Column(as: ID.Representation.self)
    let id: ID
    var name = ""
    @Column(as: SyncUp.ID.Representation.self)
    var syncUpID: SyncUp.ID
}
extension Attendee.Draft: Equatable {}

@Table
struct Meeting: Hashable, Identifiable {
    typealias ID = Tagged<Self, UUID>

    @Column(as: ID.Representation.self)
    let id: ID
    @Column(as: Date.ISO8601Representation.self)
    var date: Date
    @Column(as: SyncUp.ID.Representation.self)
    var syncUpID: SyncUp.ID
    var transcript: String
}
extension Meeting.Draft: Equatable {}

and make ID-based queries more readable:

withErrorReporting {
    self.attendees = try database.read { db in
        try Attendee.all
            .where { $0.syncUpID.eq(syncUpID.representation) }
            .fetchAll(db)
            .map { (attendee: Attendee) in AttendeeDraft(id: AttendeeDraft.ID(uuid()), name: attendee.name) }
    }
}