ProviderBuilder helper

This class simplifies the addition of providers to DI while simultaneously controlling their types. Since this class implements the so-called Iteration protocols, it facilitates the conversion of itself into an array (note the spread operator):

import { ProviderBuilder } from '@ditsmod/core';
import { restModule } from '@ditsmod/rest';
// ...
@restModule({
  // ...
  providersPerRou: [
    Provider1,
    Provider2,
    ...new ProviderBuilder().useValue<CorsOptions>(CorsOptions, { origin: 'https://example.com' }),
    // ...
  ],
  // ...
})
export class SomeModule {}

Starting from v2.55, Ditsmod allows passing an instance of ProviderBuilder directly into the providersPer* properties of the module or controller metadata:

import { ProviderBuilder } from '@ditsmod/core';
import { restModule } from '@ditsmod/rest';
// ...
@restModule({
  // ...
  providersPerRou: new ProviderBuilder()
    .passThrough(Provider1)
    .passThrough(Provider2)
    .useValue<CorsOptions>(CorsOptions, { origin: 'https://example.com' }),
  // ...
})
export class SomeModule {}

The providers.passThrough() method allows providers to be passed without type checking; it is intended for passing classes as providers.

In addition, ProviderBuilder has a special method $if(), which allows providers to be passed only if it receives a truthy value:

import { ProviderBuilder } from '@ditsmod/core';
import { restModule } from '@ditsmod/rest';
// ...
@restModule({
  // ...
  providersPerRou: new ProviderBuilder()
    .passThrough(Provider1)
    .$if(false)
    .passThrough(Provider2)
    .passThrough(Provider3),
  // ...
})
export class SomeModule {}

In this case, Provider2 will not be passed to DI, while Provider1 and Provider3 will be passed. That is, $if() applies only to the first expression immediately following it.

The providers.$use() method allows creating plugins (or middlewares) to extend the functionality of ProviderBuilder:

class Plugin1 extends ProviderBuilder {
  method1() {
    if (this.true) {
      // ...
    }
    return this.self;
  }
}

class Plugin2 extends ProviderBuilder {
  method2() {
    if (this.true) {
      // ...
    }
    return this.self;
  }
}

const providers = [...new ProviderBuilder()
  .$use(Plugin1, Plugin2)
  .method1()
  .method2()
  .useLogConfig({ level: 'trace' })
  .useClass(SomeService, ExtendedService)];