Fluent is basically damaged
The extra I exploit the Fluent ORM framework the extra I notice how laborious it’s to work with it. I am speaking a few explicit design concern that I additionally talked about within the way forward for server aspect Swift article. I actually don’t love the concept of property wrappers and summary database fashions.
What’s the issue with the present database mannequin abstraction? To start with, the elective ID property is complicated. For instance you do not have to offer an identifier while you insert a file, it may be an nil worth and the ORM system can create a novel identifier (beneath the hood utilizing a generator) for you. So why do we have now 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 want that? If you wish to determine a file that is going to be one thing like a key, not an id discipline. 🙃
Additionally this elective property may cause another points, when utilizing fluent you possibly can require an id, which is a throwing operation, alternatively you possibly can unwrap the elective property in the event you’re positive that the identifier already exists, however this isn’t a secure strategy in any respect.
My different concern is said to initializers, in the event you 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 should be lessons. BUT WHY? IMHO the explanation pertains to this concern: you possibly can question the database fashions utilizing the mannequin itself. So the mannequin acts like a repository that you need to use to question the fields, and it additionally represents the the file itself. Is not this in opposition to the clear ideas? 🤔
Okay, one final thing. Property wrappers, discipline keys and migrations. The core members at Vapor advised us that this strategy will present a secure approach to question my fashions and I can make sure that discipline keys will not be tousled, however I am really battling versioning on this case. I needed to introduce a v1, v2, vN construction each for the sphere keys and the migration, which really feels a bit worse than utilizing uncooked strings. It’s over-complicated for positive, and it feels just like the schema definition is combined up with the precise question mechanism and the mannequin layer as effectively.
Sorry people, I actually admire the hassle that you’ve got put into Fluent, however these points are actual and I do know that you may repair them on the long run and make the developer expertise quite a bit higher.
Learn how to make Fluent a bit higher?
On the brief time period I am attempting to repair these points and fortuitously there’s a good strategy to separate the question mechanism from the mannequin layer. It’s referred to 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 matter.
Anyway, the primary thought is that you just wrap the Request object right into a customized repository, it is normally a struct, then you definately solely name database associated queries inside this particular object. If we check out on the default challenge template (you possibly can generate one by utilizing the vapor toolbox), we will 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 checklist() 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, any longer you do not have to make use of the static strategies on the mannequin itself, however you need to use an occasion of the repository to change your database rows. The repository might be hooked as much as the Request object by utilizing a typical sample. The most straightforward means is to return a service each time you want it.
import Vapor
extension Request {
var todo: TodoRepository {
.init(req: self)
}
}
In fact it is a very primary answer and it pollutes the namespace beneath the Request object, I imply, when you’ve got numerous repositories this could be a downside, however first let me present you the right way to refactor the controller by utilizing this easy methodology. 🤓
import Vapor
struct TodoController: RouteCollection {
func boot(routes: RoutesBuilder) throws {
let todos = routes.grouped("todos")
todos.get(use: index)
todos.publish(use: create)
todos.group(":todoID") { todo in
todo.delete(use: delete)
}
}
func index(req: Request) async throws -> [Todo] {
attempt await req.todo.checklist()
}
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 will merely name the suitable methodology utilizing the repository occasion. Nonetheless if you wish to unit take a look at the controller it isn’t doable to mock the repository, so we have now to determine one thing about that concern. First we want 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 checklist() 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 facility 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 based mostly on the identifier. In fact this complete ceremony might be averted, however I needed to give you a generic answer to retailer repositories beneath the req.repository namespace. 😅
public struct RepositoryId: Hashable, Codable {
public let string: String
public init(_ string: String) {
self.string = string
}
}
public last 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 {
utility.repositories.builder(self)
}
}
As a developer you simply should give you a brand new distinctive identifier and prolong the RepositoryFactory together with your getter in your personal repository kind.
public extension RepositoryId {
static let todo = RepositoryId("todo")
}
public extension RepositoryFactory {
var todo: TodoRepository {
guard let end result = make(.todo) as? TodoRepository else {
fatalError("Todo repository just isn't configured")
}
return end result
}
}
We will now register the FluentTodoRepository object, we simply should rename the unique TodoRepository struct and conform to the protocol as an alternative.
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 means 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.publish(use: create)
todos.group(":todoID") { todo in
todo.delete(use: delete)
}
}
func index(req: Request) async throws -> [Todo] {
attempt await req.repositories.todo.checklist()
}
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
}
}
The perfect a part of this strategy is that you may 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 beneath the repositories key.
You’ll be able to give you a generic DatabaseRepository protocol with an related database Mannequin kind, then you might implement some primary options as a protocol extension for the Fluent fashions. I am utilizing this strategy and I am fairly proud of it thus far, what do you suppose? Ought to the Vapor core workforce add higher assist for repositories? Let me know on Twitter. ☺️
