How to write a MongoDB $slice in golang

问题

How do I write $slice MongoDB code in golang? Here is my MongoDB code:

db.userdetail.aggregate([{"$project":{"user":{"$slice":["$user",2,1]}}}]).pretty()

I try to write this code in golang:

o1 := bson.M{
        "$project":bson.M{"user":bson.M{"$slice":bson.M["$user",2,1,],},},
    }

It gives me the following err: syntax error: unexpected comma, expecting ]

回答1:

bson.M is map[string]interface not slice. And you need []interface for "$slice".

o1 := bson.M{"$project": bson.M{"user": bson.M{"$slice": []interface{}{"$user", 2, 1}}}}

If you share some dummy data, input and output, I could help you further.

来源：https://stackoverflow.com/questions/37253400/how-to-write-a-mongodb-slice-in-golang