Fluent is actually 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 few specific design problem that I additionally talked about within 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 elective ID property is complicated. For instance you do not have to supply an identifier if you insert a file, it may be an nil worth and the ORM system can create a novel identifier (underneath the hood utilizing a generator) for you. So why do we’ve got 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 determine a file that is going to be one thing like a key, not an id subject. 🙃
Additionally this elective property could cause another points, when utilizing fluent you may require an id, which is a throwing operation, alternatively you may unwrap the elective property in the event you’re positive that the identifier already exists, however this isn’t a protected method in any respect.
My different problem is said to initializers, in the event you outline a customized mannequin you all the time have to supply an empty init() {} methodology for it, in any other case the compiler will complain, as a result of fashions need to be lessons. BUT WHY? IMHO the explanation pertains to this problem: you may 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 ideas? 🤔
Okay, one final thing. Property wrappers, subject keys and migrations. The core members at Vapor instructed us that this method will present a protected option to question my fashions and I can make certain that subject keys will not be tousled, however I am really scuffling with 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 which you can repair them on the long run and make the developer expertise quite a bit higher.
The best way to make Fluent a bit higher?
On the quick time period I am making an attempt to repair these points and luckily there’s a good method to separate the question mechanism from the mannequin layer. It’s known as the repository sample and I would like to present 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 often a struct, then you definitely solely name database associated queries inside this particular object. If we check out on the default venture template (you may generate one by utilizing 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 checklist() async throws -> [Todo] {
strive await question().all()
}
func get(_ id: Todo.IDValue) async throws -> Todo? {
strive await get([id]).first
}
func get(_ ids: [Todo.IDValue]) async throws -> [Todo] {
strive await question(ids).all()
}
func create(_ mannequin: Todo) async throws -> Todo {
strive await mannequin.create(on: req.db)
return mannequin
}
func replace(_ mannequin: Todo) async throws -> Todo {
strive await mannequin.replace(on: req.db)
return mannequin
}
func delete(_ id: Todo.IDValue) async throws {
strive await delete([id])
}
func delete(_ ids: [Todo.IDValue]) async throws {
strive await question(ids).delete()
}
}
That is how we’re can manipulate Todo fashions, any more 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 will be hooked as much as the Request object by utilizing a typical sample. The simplest means 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 primary answer and it pollutes the namespace underneath the Request object, I imply, you probably have a lot of repositories this could be a drawback, however first let me present you learn how 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] {
strive await req.todo.checklist()
}
func create(req: Request) async throws -> Todo {
let todo = strive req.content material.decode(Todo.self)
return strive 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)
}
strive await req.todo.delete(id)
return .okay
}
}
As you may see this manner we had been capable of remove 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 attainable to mock the repository, so we’ve got to determine one thing about that problem. 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 function. The RepositoryRegistry will have the ability to return a manufacturing unit 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 primarily based on the identifier. In fact this complete ceremony will be prevented, however I needed to provide you with a generic answer 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 closing 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)` shouldn't be 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 need to provide you with a brand new distinctive identifier and prolong the RepositoryFactory along with your getter in your personal repository sort.
public extension RepositoryId {
static let todo = RepositoryId("todo")
}
public extension RepositoryFactory {
var todo: TodoRepository {
guard let outcome = make(.todo) as? TodoRepository else {
fatalError("Todo repository shouldn't be configured")
}
return outcome
}
}
We are able to now register the FluentTodoRepository object, we simply need to 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 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.publish(use: create)
todos.group(":todoID") { todo in
todo.delete(use: delete)
}
}
func index(req: Request) async throws -> [Todo] {
strive await req.repositories.todo.checklist()
}
func create(req: Request) async throws -> Todo {
let todo = strive req.content material.decode(Todo.self)
return strive 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)
}
strive await req.repositories.todo.delete(id)
return .okay
}
}
The perfect a part of this method is which you can merely exchange 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 sort, then you could possibly implement some primary options as a protocol extension for the Fluent fashions. I am utilizing this method and I am fairly pleased with it to date, what do you suppose? Ought to the Vapor core workforce add higher help for repositories? Let me know on Twitter. ☺️
