Question

Let’s say this is a collection of 2 Bson documents

{
    "_id": "...",
    "name": "Test1",
    "sub": {
        "street": "134 Fake Street",
        "city": "NoWhere"
    }
},
{
    "_id": "...",
    "name": "Test2",
    "sub": {
        "height": "10",
        "width": "20",
        "sub2": {
            "type": "something"
        }
    }
}

where the first level is a structured class but sub-levels can be completely unstructured and can have further nested documents several levels deep.

How can I deserialize this document to a C# class? All samples I have seen assume some structure in nested documents.

The following class gives an error:

public class Report
{
    [BsonId]
    public ObjectId _id { get; set; }

    public string name { get; set; }

    public BsonDocument sub { get; set; }
}

Type ‘MongoDB.Bson.BsonString’ with data contract name ‘…’ is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types – for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.

EDIT

What I’m trying to do might be complete non-sense. Is it a better idea to just use one BsonDocument and handle everything manually without a structured class?

Answer 1

I don’t think the error message you are getting is from the C# driver. Can you please provide a stack trace?

I’ve tried to reproduce your issue but it works fine with my test program.

The document inserted by the above test program looks like this:

> db.test.find()
{ "_id" : ObjectId("5075fc6ee447ad1354c1f018"), "name" : "John Doe", "sub" : { "x" : 1, "y" : 2 } }
>