BsonDocument

BsonDocument is the default type used for documents. It handles dynamic documents of any complexity. For instance, the document { a: 1, b: [{ c: 1 }] } can be built as follows:

var doc = new BsonDocument
{
    { "a", 1 },
    { "b", new BsonArray
           {
                new BsonDocument("c", 1)
           }}
};

In addition, there is a Parse method to make reading a JSON string simple.

var doc = BsonDocument.Parse("{ a: 1, b: [{ c: 1 }] }");