How do you add a list of bsondocuments as an element of a bsondocument

Question

How do I create the following document using the official c# driver?

{
    "name": "John Doe",
    "classess": [
        {
            "classname": "Class1"
        }
        {
            "classname": "Class2"
        }
    ]
}

The below code doesn't work

string cs = "mongodb://localhost";
MongoServer server = MongoServer.Create(cs);
MongoDatabase test = server.GetDatabase("test");

MongoCollection<BsonDocument> students = test.GetCollection("students");

BsonDocument doc = new BsonDocument();
doc.Add(new BsonElement("name", "John doe"));

//Create the list
List<BsonDocument> classes = new List<BsonDocument>();
classes.Add(new BsonDocument(new BsonElement("classname","Test1")));
classes.Add(new BsonDocument(new BsonElement("classname","Test2")));

the following line will throw an error for obvious reason. What is the proper way of doing this?

doc.Add(new BsonElement("classess",classes));
students.Insert(doc);

Thank you.

Answer 1

To create that document using only BsonDocument classes I would write:

        var document = new BsonDocument {
            { "name", "John Doe" },
            { "classes", new BsonArray {
                new BsonDocument("classname", "Class1"),
                new BsonDocument("classname", "Class2")
            }}
        };
        var json = document.ToJson();

This example is using C#'s collection initializer syntax.

The last line is just for debugging. You can look at the json variable and see if you got the result you wanted.

Answer 2

Suppose you have following classes:

public class NestedClass
{
  public string ClassName {get;set;}
}

public class Person
{
  public Person()
  {
    Classes = new List<NestedClass>();
  }  

  [BsonId]
  public string PersonId {get;set;}

  public string Name {get;set;}

  public List<NestedClass> Classes {get;set;}
}

You need:

Create create and initialize instance of class that you want to save

 var person = new Person(){PersonId = Guid.NewGuid().ToString(), Name = "Some name"};
 person.Classes.Add(new NestedClass(){ ClassName="classname1"})
 person.Classes.Add(new NestedClass(){ ClassName="classname2"})

than

var server = MongoServer.Create("mongodb://localhost:27020");
  MongoDatabase test = server.GetDatabase("test");
  MongoCollection students = test.GetCollection<Person>("students");
  students.Insert(person.ToBsonDocument()); // it will automatically serialize and insert person

Also be sure that you have run mongodb.