Created
January 13, 2019 13:59
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| // Repositories | |
| protocol Repository { | |
| associatedtype Model | |
| associatedtype Collection: Swift.Collection where Collection.Element == Model | |
| func add(_ item: Model) -> Void | |
| func add(_ items: Collection) -> Void | |
| func update(_ item: Model) -> Void | |
| func remove(_ item: Model) -> Void | |
| func remove(specification: GenericSpecification<Model>) -> Void; | |
| func query(specification: GenericSpecification<Model>) -> Observable<Model> | |
| } | |
| // One of many repositories... | |
| class MessagesRepository: Repository { | |
| func add(_ item: Message) {...} | |
| func add(_ items: [Message]) {...} | |
| func update(_ item: Message) {...} | |
| func remove(_ item: Message) {...} | |
| func remove(specification: GenericSpecification<Message>) -> Observable<Bool> { | |
| return specification.toFirestoreQuery(Firestore.firestore()) | |
| } | |
| func query(specification: GenericSpecification<Message>) -> Observable<Message> { | |
| return specification.toFirestoreQuery(Firestore.firestore()) | |
| } | |
| } | |
| // Abstract specification(s) | |
| protocol Specification {} | |
| protocol FirestoreSpecification: Specification { | |
| associatedtype Model | |
| func toFirestoreQuery(_ firestore: Firestore) -> Observable<Model> | |
| } | |
| /* | |
| We would use something like this if we decided to use something other than Firestore, such as Realm. | |
| protocol RealmSpecification: Specification { | |
| associatedtype Model | |
| func toRealmQuery(_ realm: Realm) -> Observable<Model> | |
| } | |
| */ | |
| class GenericSpecification<T>: FirestoreSpecification { | |
| func toFirestoreQuery(_ firestore: Firestore) -> Observable<T> { | |
| fatalError("Must override toFirestoreQuery(_ firestore: Firestore) -> Observable<T>?") | |
| } | |
| } | |
| // Concrete classes that conform to Specification | |
| class AllMessagesSpecification: GenericSpecification<Message> { | |
| override func toFirestoreQuery(_ firestore: Firestore) -> Observable<Message> {...} | |
| } | |
| class GetMessagesByUserIdSpecification: GenericSpecification<Message> { | |
| private let id: String | |
| init(id: String) { | |
| self.id = id | |
| } | |
| override func toFirestoreQuery(_ firestore: Firestore) -> Observable<Message> {...} | |
| } | |
| class RemoveMessageByIdSpecification: GenericSpecification<Message> { | |
| private let id: String | |
| init(id: String) { | |
| self.id = id | |
| } | |
| override func toFirestoreQuery(_ firestore: Firestore) -> Observable<Bool> {...} | |
| } | |
| // etc... | |
| // Usage: | |
| // This is just for explanation purposes | |
| let messagesRepo: MessagesRepository = MessagesRepository() | |
| // Get all messages | |
| func observeMessages() -> Observable<Message> { | |
| return messagesRepo | |
| .query(specification: AllMessagesSpecification()) | |
| } | |
| // Get all messages for a specific user | |
| func observeMessages(for userId: String) -> Observable<[Message]> { | |
| return messagesRepo | |
| .query(specification: GetMessagesByUserIdSpecification(id: userId)) | |
| .toArray() | |
| } | |
| // Remove a message with id | |
| func removeMessage(with id: String) -> Observable<Bool> { | |
| return messagesRepo | |
| .query(specification: RemoveMessageByIdSpecification(id: id)) | |
| } |
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