Scope beta Contributors are welcome

The scope of a provider defines the life cycle and visibility of that bean in the contexts in which it's used.

Ts.ED define two types of scope:

  • singleton,
  • request

The scope annotation can be used on the following providers:

Singleton scope

Singleton scope is the default behavior of all providers. That means all providers are create on the server initialization.

import {Controller, Scope, ProviderScope} from "@tsed/common";

@Controller("/")
@Scope(ProviderScope.SINGLETON)  // OPTIONAL, leaving this annotation a the same behavior
export class MyController {
    private rand = Math.random() * 100;

    @Get("/random")
    async getValue() {
        return this.rand;
    }
}
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Note

In this example all request on /random endpoint return the same random value.

Request scope

Request scope will create a new instance of provider for each request. A new container will be created and attached to the request. It'll contains all provider annotated by @Scope("request").

Example

This example is available for Middleware and Controller.

import {Controller, Scope, ProviderScope} from "@tsed/common";

@Controller("/")
@Scope(ProviderScope.REQUEST)
export class MyController {
    private rand = Math.random() * 100;

    @Get("/random")
    async getValue() {
        return this.rand;
    }
}
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Each request on /random will return a different random value.

Chain with Service

It also possible to use @Scope("request") on service if your service is injected on a controller which is annotated by @Scope("request") too.

Here a working example:

import {Controller, Scope, ProviderScope} from "@tsed/common";

@Service()
@Scope(ProviderScope.REQUEST)
export class MyService {
  public rand = Math.random() * 100;
}

@Controller("/")
@Scope(ProviderScope.REQUEST)
export class MyController {

    contructor(private myService: MyService)

    @Get("/random")
    async getValue() {
        return this.myService.rand;
    }
}
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And here a unworking example:

import {Controller, Scope, ProviderScope} from "@tsed/common";

@Service()
@Scope(ProviderScope.REQUEST)
export class MyService {
  public rand = Math.random() * 100;
}

@Controller("/")
@Scope(ProviderScope.SINGLETON) // SINGLETON avoid all Scope("request") annotation
export class MyController {

    contructor(private myService: MyService)

    @Get("/random")
    async getValue() {
        return this.myService.rand;
    }
}
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WARNING

The SINGLETON annotation avoid the @Scope("request") annotation put on MyService.

Unsupported usecase

The @Scope("request") annotation has no effect on:

  • Middlewares used on endpoint.
  • Global middlewares.

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