Mongo在Golang上的随机记录

Question

I'm trying to retrieve random records from my mongodb collection. I'm using golang with mongo-go-driver

pipeline := []bson.E{bson.E{"$sample", bson.E{"size", 10}}}
collection.Aggregate(context.TODO(), pipeline)

The aggregate is returning me this error:

A pipeline stage specification object must contain exactly one field.

I've tried with $size and size

Is it possible that mongo-go-driver doesn't support $sample?

Answer 1

Use below instead

pipeline := []bson.D{bson.D{{"$sample", bson.D{{"size", 10}}}}}

bson.D represents a BSON docoument and bson.E represents a BSON element. An aggregation is an array of BSON documents. More details can be found at https://godoc.org/go.mongodb.org/mongo-driver/bson.