db.collection.find(query, projection)

Selects documents in a collection and returns a cursor to the selected documents.

Parameter	Type	Description
query	document	Optional. Specifies selection filter using query operators. To return all documents in a collection, omit this parameter or pass an empty document ({}).
projection	document	Optional. Specifies the fields to return in the documents that match the query filter. To return all fields in the matching documents, omit this parameter. For details, see Projection.

参考：https://mongoing.com/docs/reference/method/db.collection.find.html