I think it’s just:
mongodump --db=<old_db_name> --collection=<collection_name> --out=data/
mongorestore --db=<new_db_name> --collection=<collection_name> data/<db_name>/<collection_name>.bson
Also see docs here and here.
Btw, the other way to move the collection from one database to another is to use renameCollection:
db.runCommand({renameCollection:"<old_db_name>.<collection_name>",to:"<new_db_name>.<collection_name>"})
Here’s some related SO threads:
- How to copy a collection from one database to another in MongoDB
- How to use the dumped data by mongodump?