Class StoryService

genkit-angular-story-generator/src/app/story.service.ts:21–62

  providedIn: 'root'
})
export class StoryService {
  // Used to manage app presentation state
  hasStoryStarted = signal(false);
  // Used to manage input the story description requests
  premiseInput = signal('');
  // Used to manage input the story generation requests
  storyInput = signal('');

  // Only set this on the first request.
  // Note: this approach is for demonstration purposes. Consider alternative approaches to
  // session management in a production application.
  sessionId = linkedSignal<string, string>({
    source: () => this.premiseResource.value().storyPremise,
    computation: (_newPremise, previous) => !previous ? randomId() : previous.value
  });

  // Used to determine whether to show the update story button in the UserInputComponenet
  hasPremiseUpdated = linkedSignal<string, boolean>({
    source: () => this.premiseResource.value().storyPremise,
    computation: (newPremise, previous) => !!previous && newPremise !== previous!.source
  });

  // Only clear the session on initial page load
  clearSession = linkedSignal<string, boolean>({
    source: () => this.premiseResource.value().storyPremise,
    computation: (_newPremise, previous) => !previous
  });

  // A resource that requests update story premise information based on user input
  premiseResource = resource({
    defaultValue: DEFAULT_PREMISE,
    request: () => this.premiseInput(),
    loader: ({request}): Promise<StoryPremise> => runFlow({
      url: DESCRIPTION_FLOW,
      input: {
        userInput: request,
        sessionId: this.sessionId(),
        clearSession: this.clearSession()
      }
    })
  });
}

interface StoryPremise {
  storyPremise: string;