Querying mongodb from golang using the _id stored in an array

Question

So here is my question. I have an array which are stored the _ids of mongodbs objects. Whats the right way to retrieve them all in one query using the mgo and bson package?

So if the array is like that: ids:=["543d171c5b2c12420dd016","543d171c5b2dd016"]

How we make the query ? I tried that but I know its wrong.

query := bson.M{"_id": bson.M{"$in": ids}}
c.Find(query).All()

Thanks in advance

Answer 1

If the documents are stored with string ids, then the code looks correct.

The ids look like hex encoded object ids. If the object identifiers are object ids, then you need to the convert the hex strings to object ids:

oids := make([]bson.ObjectId, len(ids))
for i := range ids {
  oids[i] = bson.ObjectIdHex(ids[i])
}
query := bson.M{"_id": bson.M{"$in": oids}}

Answer 2

MongoDB syntax for go.mongodb.org/mongo-driver has been updated, this should work using the official driver.

oids := make([]primitive.ObjectID, len(ids))
for i := range ids {
    objID, err := primitive.ObjectIDFromHex(ids[i])
    if err == nil {
        oids = append(oids, objID)
    }
}