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- $isoDayOfWeek (aggregation)
$isoDayOfWeek (aggregation)¶
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Definition¶
- $isoDayOfWeek¶
3.4 新版功能.
Returns the weekday number in ISO 8601 format, ranging from 1 (for Monday) to 7 (for Sunday).
$isoDayOfWeek has the following operator expression syntax:
{ $isoDayOfWeek: <date expression> }
The argument can be any valid expression that resolves to a BSON ISODate object, a BSON Timestamp object, or a Date object.
Behavior¶
| Example | Result |
|---|---|
| { $isoDayOfWeek: new Date("2016-01-01") } | 5 |
| { $isoDayOfWeek: new Date("Jan 7, 2003") } | 2 |
| { $isoDayOfWeek: new Date("August 14, 2011") } | 7 |
| { $isoDayOfWeek: ISODate("1998-11-07T00:00:00Z") } | 6 |
| { $isoDayOfWeek: "March 28, 1976" } | error |
| { $isoDayOfWeek: "2009-04-09" } | error |
注解
$isoDayOfWeek cannot take a string as an argument.
Example¶
A collection called birthdays contains the following documents:
{ "_id" : 1, "name" : "Betty", "birthday" : ISODate("1993-09-21T00:00:00Z") }
{ "_id" : 2, "name" : "Veronica", "birthday" : ISODate("1981-11-07T00:00:00Z") }
The following operation returns the weekday number for each birthday field.
db.dates.aggregate( [
{
$project: {
_id: 0,
name: "$name",
dayOfWeek: { $isoDayOfWeek: "$birthday" }
}
}
] )
The operation returns the following results:
{ "name" : "Betty", "dayOfWeek" : 2 }
{ "name" : "Veronica", "dayOfWeek" : 6 }