How to delete data from more than week ago?

Working with Data
1

Hello
I have a web scraper that runs everyday and I want to delete data from more than a week ago

This is my coin model so far

    const coinSchema = mongoose.Schema(
  {
    specNo: {
      type: String,
      required: true,
    },
    coinName: {
      type: String,
      required: true,
    },
    fullName: {
      type: String,
      required: false,
    },
    category: {
      type: String,
    },
    array: [
      {
        GradeName: String,
        PopulationCount: String,
        trend: { type: Number, default: 0 },
      },
    ],
  },
  {
    timestamps: true,
  }
);

and this is the delete function in my model:

>     coinSchema.statics.deleteOldData = async function () {
>   // delete old data
>   const today = new Date(Date.now());
>   today.setHours(0, 0, 0, 0);
>   const oneWeekAgo = new Date(Date.now());
>   const pastDate = oneWeekAgo.getDate() - 7;
>   oneWeekAgo.setDate(pastDate);
> 
>   await this.deleteMany({
>     createdAt: {
>       $gte: today,
>     }, // 16 < 17 wont delete it prevent duplicates for one day
>   });
>   await this.deleteMany({
>     createdAt: {
>       $lt: pastDate,
>     }, // from 1 week ago
>   });
> };

However the data from more than a week ago is still stored in my MongoDB, is there a reason for this?

1 Like
2

Welcome to the MongoDB Community Forums @Juls_Oh !

The getDate() method returns the day of the month for the specified date, so your date math doesn’t support what you are trying to do:

> oneWeekAgo = new Date(Date.now());
2021-08-22T00:57:28.369Z

> pastDate = oneWeekAgo.getDate() - 7;
15

A JavaScript Date object stores a datetime representation in milliseconds, you would want a calculation like:

>  oneWeekAgo = new Date(new Date() - (7 * 24 * 60 * 60 * 1000))
2021-08-15T00:57:52.909Z

For easier date math I’d recommend using a library like moment.js:

# Exactly 7 days ago
> moment().subtract(7,'days')
Moment<2021-08-15T11:02:26+10:00>

# Start of day 7 days ago (local timezone)
> moment().subtract
(7,'days').startOf('day')
Moment<2021-08-15T00:00:00+10:00>

# Start of day 7 days ago (UTC)
> moment().subtract(7,'days').startOf('day').utc()
Moment<2021-08-14T14:00:00Z>

Regards,
Stennie

2 Likes
3

I need to add a .toDate() method at the end to retrieve data from MongoDB, but when .toDate() changes from T00:00 to T07:00 for startOf(‘day’) (which is today). Shouldnt it be T00:00 ?

4

Hi @Juls_Oh,

Sorry, I forgot to include that in my examples. You will need toDate() to convert the Moment object to a JavaScript Date.

If you calculate start of day for local time and convert that to a JavaScript Date with toDate(), you’ll end up with a Date object in UTC which will be offset per your local timezone.

I think what you want may be:

> moment().subtract(7,'days').utc().startOf('day').toDate()
2021-08-16T00:00:00.000Z

If that isn’t what you’re looking for, can you share your specific Moment.js invocation and the expected output?

FYI there’s also a Moment Timezone extension if you want more convenient helpers for working with timezones.

Regards,
Stennie

5

Yes it is however utc() adds another extra day which is wrong in my situation. However if I remove utc() it adds 7hours to the time again.