$hour (aggregation)
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Definition
-
$hour
-
Returns the hour portion of a date as a number between 0 and 23.
The
$hour
expression has the following operator expression syntax:Changed in version 3.6.
The argument must be a valid expression that resolves to one of the following:
A document of the following form:
New in version 3.6.
Field Description date
The date to which the operator is applied. <dateExpression>
must be a valid expression that resolves to a Date, a Timestamp, or an ObjectID.timezone
Optional.
The timezone of the operation result.<tzExpression>
must be a valid expression that resolves to a string formatted as either an Olson Timezone Identifier or a UTC Offset . If notimezone
is provided, the result is displayed inUTC
.Format
Examples
Olson Timezone Identifier "America/New_York" "Europe/London" "GMT"
UTC Offset +/-[hh]:[mm], e.g. "+04:45" +/-[hh][mm], e.g. "-0530" +/-[hh], e.g. "+03"
Behavior
Example | Result |
---|---|
12 | |
0 | |
18 | |
0 | |
5 | |
error |
|
error |
|
error |
Note
$hour
cannot take a string as an argument.
Example
Consider a sales
collection with the following document:
The following aggregation uses the $hour
and other date expressions to break down the date
field:
The operation returns the following result: