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- $month (aggregation)
$month (aggregation)¶
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Definition¶
- $month¶
Returns the month of a date as a number between 1 and 12.
The $month expression has the following syntax:
{ $month: <expression> }
The argument can be any expression as long as it resolves to a date. For more information on expressions, see Expressions.
Example¶
Consider a sales collection with the following document:
{ "_id" : 1, "item" : "abc", "price" : 10, "quantity" : 2, "date" : ISODate("2014-01-01T08:15:39.736Z") }
The following aggregation uses the $month and other date operators to break down the date field:
db.sales.aggregate(
[
{
$project:
{
year: { $year: "$date" },
month: { $month: "$date" },
day: { $dayOfMonth: "$date" },
hour: { $hour: "$date" },
minutes: { $minute: "$date" },
seconds: { $second: "$date" },
milliseconds: { $millisecond: "$date" },
dayOfYear: { $dayOfYear: "$date" },
dayOfWeek: { $dayOfWeek: "$date" },
week: { $week: "$date" }
}
}
]
)
The operation returns the following result:
{
"_id" : 1,
"year" : 2014,
"month" : 1,
"day" : 1,
"hour" : 8,
"minutes" : 15,
"seconds" : 39,
"milliseconds" : 736,
"dayOfYear" : 1,
"dayOfWeek" : 4,
"week" : 0
}
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