How to convert List<BsonDocument> to List<Class> in C#

var collection = context.Db.GetCollection<BsonDocument>("DBCollection");

should be:

var collection = context.Db.GetCollection<MyClass>("DBCollection");

That way you can use the Find method to check your FileName and FileNumber using something like:

var objList = await collection.Find(x => x.FileName == "FILENAMEHERE" && x.FileNumber == 1).ToListAsync();

Another Answer:

The list of BsonDocuments can be converted directly to a list of class objects with one line of code.

var objList = JsonConvert.DeserializeObject<List<classname>>(bsonDocList.ToJson());

Make sure you are converting the list of bsondocuments to json and not a string. Hope this helps!