Document.swift

Document.swift

import Foundation
import FirebaseFirestore
import FirebaseFirestoreSwift

protocol SetIdentifiable: Identifiable {
  mutating func set(id: ID)
}

typealias AnyEntity = Codable & Sendable & Hashable & Identifiable & SetIdentifiable
// onCall等でEntityを返す際にDocumentIDで以下のエラーになる。そのためonCallでのレスポンスはEntityを使用して、Firestoreからのデータ取得はDocument<Entity>を使用する
//   - decodingIsNotSupported : "Could not find DocumentReference for user info key: CodingUserInfoKey(rawValue: \"DocumentRefUserInfoKey\").\nDocumentID values can only be decoded with Firestore.Decoder"
@dynamicMemberLookup
struct Document<Entity: AnyEntity>: Hashable, Identifiable, Sendable {
  @DocumentID var id: Identifier<Entity>?
  var entity: Entity

  @ClientCreatedTimestamp var createdDateTime: Date?
  @ClientUpdatedTimestamp var updatedDateTime: Date?
  @ServerCreatedTimestamp var serverCreatedDateTime: Date?
  @ServerUpdatedTimestamp var serverUpdatedDateTime: Date?

  enum TimestampCodingKeys: CodingKey {
    case createdDateTime
    case updatedDateTime
    case serverCreatedDateTime
    case serverUpdatedDateTime
  }

  subscript <V>(dynamicMember keyPath: WritableKeyPath<Entity, V>) -> V {
    get {
      entity[keyPath: keyPath]
    }
    set {
      entity[keyPath: keyPath] = newValue
    }
  }

  subscript <V>(dynamicMember keyPath: KeyPath<Entity, V>) -> V {
    entity[keyPath: keyPath]
  }
}

extension Document: Codable where Entity.ID == Self.ID {
  init(from decoder: Decoder) throws {
    let singleValueContainer = try decoder.singleValueContainer()
    _id = try singleValueContainer.decode(DocumentID<Identifier<Entity>>.self)
    entity = try singleValueContainer.decode(Entity.self)
    entity.set(id: id)

    let timestamps = try decoder.container(keyedBy: TimestampCodingKeys.self)
    _createdDateTime = try timestamps.decodeIfPresent(ClientCreatedTimestamp.self, forKey: .createdDateTime) ?? .init(wrappedValue: nil)
    _updatedDateTime = try timestamps.decodeIfPresent(ClientUpdatedTimestamp.self, forKey: .updatedDateTime) ?? .init(wrappedValue: nil)
    _serverCreatedDateTime = try timestamps.decodeIfPresent(ServerCreatedTimestamp.self, forKey: .serverCreatedDateTime) ?? .init(wrappedValue: nil)
    _serverUpdatedDateTime = try timestamps.decodeIfPresent(ServerUpdatedTimestamp.self, forKey: .serverUpdatedDateTime) ?? .init(wrappedValue: nil)
  }

  func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()
    try container.encode(entity)

    var timestamps = encoder.container(keyedBy: TimestampCodingKeys.self)
    try timestamps.encode(createdDateTime, forKey: .createdDateTime)
    try timestamps.encode(updatedDateTime, forKey: .updatedDateTime)
    try timestamps.encode(serverCreatedDateTime, forKey: .serverCreatedDateTime)
    try timestamps.encode(serverUpdatedDateTime, forKey: .serverUpdatedDateTime)
  }
}

FirestoreのDocumentと、onCallでDocumentを返却するときにTimestampの情報がonCallの場合は欠落するので(FirestoreのSDKを通さないレスポンスだから)、頑張って共通化した。上手くいったけど、型宣言の時に都度 Document という宣言になるのとうっかりすると同じCollectionでDocumentアリ・ナシの別の型で.setとかしちゃいそうなので供養