Fluent is actually damaged
The extra I take advantage of the Fluent ORM framework the extra I notice how laborious it’s to work with it. I am speaking a few explicit design subject that I additionally talked about in the way forward for server aspect Swift article. I actually don’t love the thought of property wrappers and summary database fashions.
What’s the issue with the present database mannequin abstraction? To begin with, the optionally available ID property is complicated. For instance you do not have to offer an identifier once you insert a report, it may be an nil worth and the ORM system can create a singular identifier (below the hood utilizing a generator) for you. So why do now we have an id for create operations in any respect? Sure, you may say that it’s doable to specify a customized identifier, however actually what number of occasions do we’d like that? If you wish to establish a report that is going to be one thing like a key, not an id discipline. 🙃
Additionally this optionally available property could cause another points, when utilizing fluent you possibly can require an id, which is a throwing operation, alternatively you possibly can unwrap the optionally available property if you happen to’re certain that the identifier already exists, however this isn’t a protected strategy in any respect.
My different subject is expounded to initializers, if you happen to outline a customized mannequin you all the time have to offer an empty init() {} methodology for it, in any other case the compiler will complain, as a result of fashions need to be courses. BUT WHY? IMHO the rationale pertains to this subject: you possibly can question the database fashions utilizing the mannequin itself. So the mannequin acts like a repository that you should use to question the fields, and it additionally represents the the report itself. Is not this in opposition to the clear rules? 🤔
Okay, one last item. Property wrappers, discipline keys and migrations. The core members at Vapor instructed us that this strategy will present a protected option to question my fashions and I can make certain that discipline keys will not be tousled, however I am truly combating versioning on this case. I needed to introduce a v1, v2, vN construction each for the sector keys and the migration, which truly feels a bit worse than utilizing uncooked strings. It’s over-complicated for certain, and it feels just like the schema definition is blended up with the precise question mechanism and the mannequin layer as nicely.
Sorry of us, I actually respect the hassle that you’ve got put into Fluent, however these points are actual and I do know you can repair them on the long run and make the developer expertise lots higher.
How one can make Fluent a bit higher?
On the quick time period I am attempting to repair these points and luckily there’s a good strategy to separate the question mechanism from the mannequin layer. It’s known as the repository sample and I might like to provide an enormous credit score to 0xTim once more, as a result of he made a cool reply on StackOverlow about this subject.
Anyway, the principle concept is that you simply wrap the Request object right into a customized repository, it is often a struct, then you definately solely name database associated queries inside this particular object. If we check out on the default undertaking template (you possibly can generate one through the use of the vapor toolbox), we are able to simply create a brand new repository for the Todo fashions.
import Vapor
import Fluent
struct TodoRepository {
var req: Request
init(req: Request) {
self.req = req
}
func question() -> QueryBuilder<Todo> {
Todo.question(on: req.db)
}
func question(_ id: Todo.IDValue) -> QueryBuilder<Todo> {
question().filter(.$id == id)
}
func question(_ ids: [Todo.IDValue]) -> QueryBuilder<Todo> {
question().filter(.$id ~~ ids)
}
func record() async throws -> [Todo] {
attempt await question().all()
}
func get(_ id: Todo.IDValue) async throws -> Todo? {
attempt await get([id]).first
}
func get(_ ids: [Todo.IDValue]) async throws -> [Todo] {
attempt await question(ids).all()
}
func create(_ mannequin: Todo) async throws -> Todo {
attempt await mannequin.create(on: req.db)
return mannequin
}
func replace(_ mannequin: Todo) async throws -> Todo {
attempt await mannequin.replace(on: req.db)
return mannequin
}
func delete(_ id: Todo.IDValue) async throws {
attempt await delete([id])
}
func delete(_ ids: [Todo.IDValue]) async throws {
attempt await question(ids).delete()
}
}That is how we’re can manipulate Todo fashions, to any extent further you do not have to make use of the static strategies on the mannequin itself, however you should use an occasion of the repository to change your database rows. The repository may be hooked as much as the Request object through the use of a typical sample. The simplest method is to return a service each time you want it.
import Vapor
extension Request {
var todo: TodoRepository {
.init(req: self)
}
}In fact this can be a very fundamental resolution and it pollutes the namespace below the Request object, I imply, when you’ve got a lot of repositories this could be a downside, however first let me present you learn how to refactor the controller through the use of this easy methodology. 🤓
import Vapor
struct TodoController: RouteCollection {
func boot(routes: RoutesBuilder) throws {
let todos = routes.grouped("todos")
todos.get(use: index)
todos.submit(use: create)
todos.group(":todoID") { todo in
todo.delete(use: delete)
}
}
func index(req: Request) async throws -> [Todo] {
attempt await req.todo.record()
}
func create(req: Request) async throws -> Todo {
let todo = attempt req.content material.decode(Todo.self)
return attempt await req.todo.create(todo)
}
func delete(req: Request) async throws -> HTTPStatus {
guard let id = req.parameters.get("todoID", as: Todo.IDValue.self) else {
throw Abort(.notFound)
}
attempt await req.todo.delete(id)
return .okay
}
}As you possibly can see this fashion we have been capable of get rid of the Fluent dependency from the controller, and we are able to merely name the suitable methodology utilizing the repository occasion. Nonetheless if you wish to unit take a look at the controller it’s not doable to mock the repository, so now we have to determine one thing about that subject. First we’d like some new protocols.
public protocol Repository {
init(_ req: Request)
}
public protocol TodoRepository: Repository {
func question() -> QueryBuilder<Todo>
func question(_ id: Todo.IDValue) -> QueryBuilder<Todo>
func question(_ ids: [Todo.IDValue]) -> QueryBuilder<Todo>
func record() async throws -> [Todo]
func get(_ ids: [Todo.IDValue]) async throws -> [Todo]
func get(_ id: Todo.IDValue) async throws -> Todo?
func create(_ mannequin: Todo) async throws -> Todo
func replace(_ mannequin: Todo) async throws -> Todo
func delete(_ ids: [Todo.IDValue]) async throws
func delete(_ id: Todo.IDValue) async throws
}Subsequent we will outline a shared repository registry utilizing the Software extension. This registry will enable us to register repositories for given identifiers, we’ll use the RepositoryId struct for this goal. The RepositoryRegistry will be capable to return a manufacturing unit occasion with a reference to the required request and registry service, this fashion we’re going to have the ability to create an precise Repository primarily based on the identifier. In fact this entire ceremony may be prevented, however I needed to provide you with a generic resolution to retailer repositories below the req.repository namespace. 😅
public struct RepositoryId: Hashable, Codable {
public let string: String
public init(_ string: String) {
self.string = string
}
}
public ultimate class RepositoryRegistry {
personal let app: Software
personal var builders: [RepositoryId: ((Request) -> Repository)]
fileprivate init(_ app: Software) {
self.app = app
self.builders = [:]
}
fileprivate func builder(_ req: Request) -> RepositoryFactory {
.init(req, self)
}
fileprivate func make(_ id: RepositoryId, _ req: Request) -> Repository {
guard let builder = builders[id] else {
fatalError("Repository for id `(id.string)` just isn't configured.")
}
return builder(req)
}
public func register(_ id: RepositoryId, _ builder: @escaping (Request) -> Repository) {
builders[id] = builder
}
}
public struct RepositoryFactory {
personal var registry: RepositoryRegistry
personal var req: Request
fileprivate init(_ req: Request, _ registry: RepositoryRegistry) {
self.req = req
self.registry = registry
}
public func make(_ id: RepositoryId) -> Repository {
registry.make(id, req)
}
}
public extension Software {
personal struct Key: StorageKey {
typealias Worth = RepositoryRegistry
}
var repositories: RepositoryRegistry {
if storage[Key.self] == nil {
storage[Key.self] = .init(self)
}
return storage[Key.self]!
}
}
public extension Request {
var repositories: RepositoryFactory {
software.repositories.builder(self)
}
}As a developer you simply need to provide you with a brand new distinctive identifier and prolong the RepositoryFactory along with your getter on your personal repository sort.
public extension RepositoryId {
static let todo = RepositoryId("todo")
}
public extension RepositoryFactory {
var todo: TodoRepository {
guard let consequence = make(.todo) as? TodoRepository else {
fatalError("Todo repository just isn't configured")
}
return consequence
}
}We will now register the FluentTodoRepository object, we simply need to rename the unique TodoRepository struct and conform to the protocol as a substitute.
public struct FluentTodoRepository: TodoRepository {
var req: Request
public init(_ req: Request) {
self.req = req
}
func question() -> QueryBuilder<Todo> {
Todo.question(on: req.db)
}
}
app.repositories.register(.todo) { req in
FluentTodoRepository(req)
}We’re going to have the ability to get the repository by way of the req.repositories.todo property. You do not have to vary anything contained in the controller file.
import Vapor
struct TodoController: RouteCollection {
func boot(routes: RoutesBuilder) throws {
let todos = routes.grouped("todos")
todos.get(use: index)
todos.submit(use: create)
todos.group(":todoID") { todo in
todo.delete(use: delete)
}
}
func index(req: Request) async throws -> [Todo] {
attempt await req.repositories.todo.record()
}
func create(req: Request) async throws -> Todo {
let todo = attempt req.content material.decode(Todo.self)
return attempt await req.repositories.todo.create(todo)
}
func delete(req: Request) async throws -> HTTPStatus {
guard let id = req.parameters.get("todoID", as: Todo.IDValue.self) else {
throw Abort(.notFound)
}
attempt await req.repositories.todo.delete(id)
return .okay
}
}One of the best a part of this strategy is you can merely change the FluentTodoRepository with a MockTodoRepository for testing functions. I additionally like the truth that we do not pollute the req.* namespace, however each single repository has its personal variable below the repositories key.
You possibly can provide you with a generic DatabaseRepository protocol with an related database Mannequin sort, then you might implement some fundamental options as a protocol extension for the Fluent fashions. I am utilizing this strategy and I am fairly proud of it up to now, what do you suppose? Ought to the Vapor core staff add higher assist for repositories? Let me know on Twitter. ☺️
