如何在 nestjs 应用程序中使用 moment

Question

I want to use momentjs in a nestjs app, and also be able to test my services. So I provided momentjs as below in my module

providers: [
    {
      provide: 'MomentWrapper',
      useFactory: async () => moment(),
      scope: Scope.REQUEST,
    },
  ],

and in my service

    constructor(
        @Inject('MomentWrapper') private momentWrapper: moment.Moment
    )

Then I have a method like this

    private calculateNextRun(every: number, period: SchedulePeriod): string {
        const currentDate = this.momentWrapper.tz('America/Toronto');
        let nextDate = null;

        nextDate = currentDate.add(every, period);
        console.log(currentDate.format(), nextDate.format(), every, period, );

        return nextDate.toISOString();
    }

This method will be called in a loop, and supposed to get the current date and add some days/weeks/.. to it and return it.

The issue is it keeps the old value so each time it goes into the method is not starting from current date

console output

2020-01-25T16:39:19-05:00 2020-01-25T16:39:19-05:00 6 d
2020-02-15T16:39:19-05:00 2020-02-15T16:39:19-05:00 3 w
2020-02-16T16:39:19-05:00 2020-02-16T16:39:19-05:00 1 d

If you see first date, which is currentDate keep changing

Is there any way to overcome this issue, without creating a new service like this

import * as moment from 'moment-timezone';
@Injectable()
export class MomentService {
    moment(): moment.Moment {
        return moment();
    }
}

Answer 1

You should create a new moment instance for each function call and not reuse the same instance of your provider singleton. So provide moment instead of moment() :

providers: [
    {
      provide: 'MomentWrapper',
      useValue: moment
    },
  ],

Answer 2

This works fine for me:

// in some *.service.ts
import * as moment form 'moment';


{ userIsRegistredOn: moment()}