Aggregation Expression - $size

Function Build

Build $size with the Size function from the aggregation package.

// bson.D{bson.E{Key:"tagCount", Value:bson.D{bson.E{Key:"$size", Value:"$tags"}}}}
result := aggregation.Size("tagCount", "$tags")

Method Build (Builder)

Build $size with the Size method from aggregation.NewBuilder().

// bson.D{bson.E{Key:"tagCount", Value:bson.D{bson.E{Key:"$size", Value:"$tags"}}}}
result := aggregation.NewBuilder().
    Size("tagCount", "$tags").
    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.

SizeWithoutKey

Function build:

// bson.D{bson.E{Key:"$size", Value:"$tags"}}
expr := aggregation.SizeWithoutKey("$tags")

Method build (Builder):

// bson.D{bson.E{Key:"$size", Value:"$tags"}}
expr := aggregation.NewBuilder().
    SizeWithoutKey("$tags").
    Build()