Introduction to MongoDB $isoWeek Operator

MongoDB is a non-relational database that supports flexible data models and rich query languages. One of its operators, $isoWeek, can be used to process and filter date data, and this article will provide a detailed introduction to its syntax, use cases, examples, and conclusions.

Syntax

The $isoWeek operator is used to return the ISO week number of a given date. Its syntax format is as follows:

{ $isoWeek: <dateExpression> }

Here, <dateExpression> represents the date expression to be processed, which can be a date-type field, a date-type variable, or a function that returns a date type, etc.

Use Cases

The $isoWeek operator is typically used in the following scenarios:

  • Query data based on week numbers: The $isoWeek operator can be used to query data for a specific week, such as finding sales records for the 30th week of a year.
  • Count data by week: The $group operation and $isoWeek operator can be used to count data by week, such as calculating the average sales or total order volume per week.
  • Sort data: The $sort operation and $isoWeek operator can be used to sort data by week number, such as sorting sales records in ascending order by week.

Examples

Here is an example using the $isoWeek operator. Suppose we have a sales collection containing sales records for different dates. We can use the $isoWeek operator to query sales records for a specific week.

Sample Data

{
  "_id": 1,
  "date": ISODate("2022-02-28T00:00:00Z"),
  "amount": 100
}
{
  "_id": 2,
  "date": ISODate("2022-03-01T00:00:00Z"),
  "amount": 200
}
{
  "_id": 3,
  "date": ISODate("2022-03-05T00:00:00Z"),
  "amount": 300
}

Sample Code

Query sales records for week 9 (from February 28, 2022 to March 6, 2022):

db.sales.find({ $expr: { $eq: [{ $isoWeek: "$date" }, 9] } })

Sample Output

{
  "_id": 1,
  "date": ISODate("2022-02-28T00:00:00Z"),
  "amount": 100
}
{
  "_id": 2,
  "date": ISODate("2022-03-01T00:00:00Z"),
  "amount": 200
}

Conclusion

The $isoWeek operator is a useful tool for processing date data in MongoDB, and can be used for date filtering, counting, and sorting.