Fluent is basically damaged
The extra I take advantage of the Fluent ORM framework the extra I notice how exhausting it’s to work with it. I am speaking a couple of explicit design subject that I additionally talked about in the way forward for server facet Swift article. I actually do not like the concept of property wrappers and summary database fashions.
What’s the issue with the present database mannequin abstraction? Initially, the optionally available ID property is complicated. For instance you do not have to supply an identifier once you insert a file, it may be an nil worth and the ORM system can create a singular identifier (underneath the hood utilizing a generator) for you. So why do we now have an id for create operations in any respect? Sure, you may say that it’s attainable to specify a customized identifier, however actually what number of occasions do we want that? If you wish to establish a file that is going to be one thing like a key, not an id area. ?
Additionally this optionally available property may cause another points, when utilizing fluent you’ll be able to require an id, which is a throwing operation, alternatively you’ll be able to unwrap the optionally available property should you’re certain that the identifier already exists, however this isn’t a secure method in any respect.
My different subject is expounded to initializers, should you outline a customized mannequin you all the time have to supply an empty init() {} technique for it, in any other case the compiler will complain, as a result of fashions must be courses. BUT WHY? IMHO the explanation pertains to this subject: you’ll be able to question the database fashions utilizing the mannequin itself. So the mannequin acts like a repository that you should utilize to question the fields, and it additionally represents the the file itself. Is not this in opposition to the clear rules? ?
Okay, one very last thing. Property wrappers, area keys and migrations. The core members at Vapor informed us that this method will present a secure technique to question my fashions and I can ensure that area keys will not be tousled, however I am truly scuffling with 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 people, I actually respect the trouble that you have put into Fluent, however these points are actual and I do know which you can repair them on the long run and make the developer expertise rather a lot higher.
make Fluent a bit higher?
On the quick time period I am attempting to repair these points and happily there’s a good method to separate the question mechanism from the mannequin layer. It’s referred to as the repository sample and I would 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 principle thought is that you just 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 challenge template (you’ll be able to 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 should utilize an occasion of the repository to change your database rows. The repository may be hooked as much as the Request object by utilizing a standard sample. The simplest approach 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 resolution and it pollutes the namespace underneath the Request object, I imply, in case you have plenty of repositories this is usually a downside, however first let me present you tips on how to refactor the controller by utilizing this straightforward technique. ?
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.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’ll be able to see this manner we had been in a position to eradicate the Fluent dependency from the controller, and we will merely name the suitable technique utilizing the repository occasion. Nonetheless if you wish to unit check the controller it isn’t attainable to mock the repository, so we now have to determine one thing about that subject. 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 objective. The RepositoryRegistry will be capable to return a manufacturing facility occasion with a reference to the required request and registry service, this manner we’re going to have the ability to create an precise Repository based mostly on the identifier. In fact this complete ceremony may be prevented, however I wished to provide you with a generic resolution to retailer repositories underneath the req.repository namespace. ?
public struct RepositoryId: Hashable, Codable {
public let string: String
public init(_ string: String) {
self.string = string
}
}
public remaining class RepositoryRegistry {
non-public let app: Software
non-public 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)` shouldn't be configured.")
}
return builder(req)
}
public func register(_ id: RepositoryId, _ builder: @escaping (Request) -> Repository) {
builders[id] = builder
}
}
public struct RepositoryFactory {
non-public var registry: RepositoryRegistry
non-public 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 {
non-public 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 must provide you with a brand new distinctive identifier and prolong the RepositoryFactory along 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 shouldn't be configured")
}
return end result
}
}We are able to now register the FluentTodoRepository object, we simply must 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 means of the req.repositories.todo property. You do not have to vary the rest 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.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 very best a part of this method is which you can merely substitute 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 underneath the repositories key.
You’ll be able to provide you with a generic DatabaseRepository protocol with an related database Mannequin kind, then you would implement some primary options as a protocol extension for the Fluent fashions. I am utilizing this method and I am fairly proud of it to this point, what do you assume? Ought to the Vapor core workforce add higher assist for repositories? Let me know on Twitter. ??