Insert into MongoDB and store the ObjectID?

So I have a problem, and a few leads on how to fix it. I need help figuring out which one will actually work, and how to execute it.

I'm programming in GoLang and using the mgo package to interact with MongoDB. At a basic level, I need to insert an entry into a collection in Mongo and also have access to that entry's ObjectID.

My first solution would be to search for the entry that matches all the data that I just inserted, but there may be duplicates. I need the EXACT entry.

Second, I would make a field in each entry that's unique, but I don't want useless data in there and I'm also running this concurrently, which can cause problems if I'm trying to make things unique yadda yadda.

Third, there's a NewObjectID() function in mgo, but I don't know how to ensure that it's a Unique ID.

Is there potential in any of these leads or how else can I tackle this?

Solution

Create an id with NewObjectId. The bson package ensures that the id is unique.

id := bson.NewObjectId()

Set the id in the document before inserting it. Store the field with the name "_id".

struct MyDoc {
   ID bson.ObjectId `bson:"_id"`
   // other fields
}

d := &MyDoc{ID: bson.NewObjectId(), /* set other fields */ }

if err := c.Insert(d); err != nil {
    // handle error
}

The inserted document has the identifier id.