Check object existence in mongo using gopkg.in/mgo.v2

Question

I am looking for convinient way to check if object already exists in collection. For now the only way that i have found is

type result interface{}
var res re         


        

Answer 1

in the Official Mongo Driver you can get count of documents with specific key using CountDocuments function :

count, err := collection.CountDocuments(context.TODO(), bson.D{{"key", "value"}})

Answer 2

count, err = collection.Find(bson.M{field: value}).Count()

Answer 3

you have to use $exists

Syntax: { field: { $exists: } }

For more details

http://docs.mongodb.org/manual/reference/operator/query/exists/