Extensions

Sustain extension is different from middlewares, with the extension we can touch the core of the application from a piece of code outside it

Request Logger

Let's take down one of the core extensions the request-logger.extension.ts

...
@Injectable()
export class RequestLoggerExtension implements SustainExtension {
  onResquestStartHook(request: SustainRequest) {
    request.startAt = new Date();
  }
  onResponseEndHook(request: SustainRequest, response: SustainResponse) {
    const endTime: any = new Date();
    const timeDiff: any = endTime - request.startAt;
    let color;
    if (response.statusCode < 400) {
      color = `\x1b[32m$$\x1b[0m `;
    } else {
      color = `\x1B[31m$$\x1b[0m`;
    }
    console.log(
      color.replace('$$', `${request.method} ${request.url}`),
      `${response.statusCode}`,
      'in ',
      timeDiff,
      'ms'
    );
  }
}

An extension is simply a class that implements SustainExtension with hooks that will be executed when the event occurs

Hooks

Sustain hooks are a lifecycle event for the application and the user requests

Hook name	params	Description
onResquestStartHook	request: SustainRequest	Execute when start treating a request
onResponseEndHook	request: SustainRequest response: SustainResponse	Execute when treating a request is done