States can implement life-cycle events.

ngxsOnInit

If a state implements the NgxsOnInit interface, its ngxsOnInit method will be invoked after all the states from the state's module definition have been initialized and pushed into the state stream. The states' ngxsOnInit methods are invoked in a topological sorted order going from parent to child. The first parameter is the StateContext where you can get the current state and dispatch actions as usual.

export interface ZooStateModel {
  animals: string[];
}
​
@State<ZooStateModel>({
  name: 'zoo',
  defaults: {
    animals: []
  }
})
export class ZooState implements NgxsOnInit {
  ngxsOnInit(ctx: StateContext<ZooStateModel>) {
    console.log('State initialized, now getting animals');
    ctx.dispatch(new GetAnimals());
  }
}

ngxsAfterBootstrap

If a state implements the NgxsAfterBootstrap interface, its ngxsAfterBootstrap method will be invoked after the root view and all its children have been rendered, because Angular invokes functions, retrieved from the injector by APP_BOOTSTRAP_LISTENER token, only after creating and attaching ComponentRef of the root component to the tree of views.

export interface ZooStateModel {
  animals: string[];
}
​
@State<ZooStateModel>({
  name: 'zoo',
  defaults: {
    animals: []
  }
})
export class ZooState implements NgxsAfterBootstrap {
  ngxsAfterBootstrap(ctx: StateContext<ZooStateModel>) {
    console.log('The application has been fully rendered');
    ctx.dispatch(new GetAnimals());
  }
}

Feature modules order of imports

If you have feature modules they need to be imported after the root module:

// feature.module.ts
@NgModule({
  imports: [
    NgxsModule.forFeature([FeatureState])
  ]
})
export class FeatureModule{}
​
// app.module.ts
@NgModule({
  imports: [
    NgxsModule.forRoot([]),
    FeatureModule,
  ]
})
export class AppModule {}