returns the first document matching the query query.
- To use MongoCollectionFindOne, you first need to load MongoLink using Needs["MongoLink`"].
- Both query and projection are Associations.
- See "Query and Projection Operators" in the MongoDB documentation for available query and projection operators.
- MongoCollectionFindOne corresponds to db.collection.findOne() in the MongoDB documentation.
- See also the "Query Documents" and "Project Fields to Return from Query" tutorials in the MongoDB documentation.