Aggregation Expression - $month

Function Build

Build $month with the Month function from the aggregation package.

// bson.D{bson.E{Key:"month", Value:bson.D{bson.E{Key:"$month", Value:time.Now()}}}}
result := aggregation.Month("month", time.Now())

Method Build (Builder)

Build $month with the MonthWithTimezone method from aggregation.NewBuilder().

// bson.D{bson.E{Key:"month", Value:bson.D{bson.E{Key:"$month", Value:time.Now()}}}}
result := aggregation.NewBuilder().
    MonthWithTimezone("month", time.Now(), "Asia/Shanghai").
    Build()

Build Without Key

When an expression needs to be passed as an argument to another expression, use a WithoutKey variant to build an expression fragment without an output field name.

MonthWithoutKey

Function build:

now := time.Now()

// bson.D{bson.E{Key:"$month", Value:now}}
expr := aggregation.MonthWithoutKey(now)

Method build (Builder):

now := time.Now()

// bson.D{bson.E{Key:"$month", Value:now}}
expr := aggregation.NewBuilder().
    MonthWithoutKey(now).
    Build()

MonthWithTimezoneWithoutKey

Function build:

now := time.Now()

// bson.D{bson.E{Key:"$month", Value:bson.D{bson.E{Key:"date", Value:now}, bson.E{Key:"timezone", Value:"Asia/Shanghai"}}}}
expr := aggregation.MonthWithTimezoneWithoutKey(now, "Asia/Shanghai")

Method build (Builder):

now := time.Now()

// bson.D{bson.E{Key:"$month", Value:bson.D{bson.E{Key:"date", Value:now}, bson.E{Key:"timezone", Value:"Asia/Shanghai"}}}}
expr := aggregation.NewBuilder().
    MonthWithTimezoneWithoutKey(now, "Asia/Shanghai").
    Build()