[V6] Singleton per-request?

[holoyan]

Is there a way to bind singleton per-request?

// scope.ts


export default class Scope {
 value = 0
}


// provider.ts

this.app.container.singleton('scope', async () => {
  return new Scope()
})


// routes.ts

// first call this
router.get('/', async () => {

  const scope = await app.container.make('scope')
  scope.value = 5

})

// then call localhost/test2
router.get('/test2', async () => {

  const scope = await app.container.make('scope')
  console.log(scope.value) // curentlly it will print 5 but I want to have 0
})

Is there a way we can make singleton per-request through IoC container?

Update:

I know how to do that using middleware, I'm just wondering if there is a way to do like in the nest

[thetutlage]

Middleware is the way to go. As per me, its a bit more explicit and easy to reason about, since you can clearly understand the flow how and when a binding is registered in the container.

Lemme know if you have any specific struggles with the middleware approach?

[holoyan]

// scope.ts

export default class Scope {
 value = 0
}

So the goal is to have new singleton object for ONLY current request lifesycle, which developers can invoke anywhere inside the project (controller, service class and so on...) and change value property.

And the reason why I don't like middleware approach is because I've to strictly bind my Scope object to the request class and pass that request everywhere in the project

(Hope I didn't miss anything from the docs)

Request.getter('scope', function (this: Request) {
  return new Scope()
})

// MyService.ts


foo(ctx: HttpContext){

// Scope is kind of internal 'thing' and I don't thing it's good aproach to get it from the input
  ctx.request.input('scope').value = 5

}

Instead I wanted to have something like this

// bind Scope

this.app.container.singletonPerHttpRequest('scope', async () => {
  return new Scope()
})

}

and then everywhere I can just get it from the container

// SomeService.ts

  const scope = await app.container.make('scope')
  scope.value = 5

[RomainLanz]

You can bind an injectable value in your middleware.

handle(ctx: HttpContext, next: NextFn) {
  const scope = new Scope()
  ctx.containerResolver.bindValue(Scope, scope)
}

Then:

@inject()
class MyService {
  constructor(private scope: Scope) {}
}

[holoyan]

Thanks @RomainLanz , it does the trick.

I'm just curious why multiple concurrent requests not overriding each other, would you mind to give a short explaination

ctx.containerResolver.bindValue(Scope, scope)

I tought binding is 'just' a key-value pairs and becouse we have single instance of IoC container it will override to each other on every request.

[thetutlage]

The ctx.containerResolver is an isolated bucket of bindings. Think of it as follows.

createServer(() => {
  const ctx = createContext()
  ctx.containerResolver = {}

  await executeRequestHandlers(ctx)
})

So the values to put into containerResolver are isolated.

[holoyan]

Now that makes sense,

Thank you @thetutlage