指定的方法不支持保存mongodb集合

Question

I'm working in a ASP MVC + Mongodb App, so I want to save files inside a specific document through a List. I'm using GridFs Upload Method which returns a MongoGridFSFileInfo (The type of the List in my Model) so I get the reference to the object returned and Add it to the List --so far everything seems fine-- but when I try to save the changes in the collection I get this exception "The specified method is not supported" and the File won't save into the document.

This is my Model

public class Document
    {

        [BsonRepresentation(BsonType.ObjectId)]
        public string Id { get; set; }
        public string Name { get; set; }
        public string  Description { get; set; }
        public List<MongoGridFSFileInfo> FsFileInfos = new List<MongoGridFSFileInfo>(); 

        public Document()
        {

        }

    }

And Here is the Method where 1) Add a File to a List of Document Collection 2) Try to save the changes in the collection.

[HttpPost]
        public ActionResult PrepareToAttach(string id, string description, HttpPostedFileBase raw_file)
        {
            Document doc = Context.FindById(id);

            var options = new MongoGridFSCreateOptions
            {
                ContentType = raw_file.ContentType
            }; 
            var mongoFileInfo = Context._db.GridFS.Upload(raw_file.InputStream, raw_file.FileName,options);

            doc.FsFileInfos.Add(mongoFileInfo);
            Context.Documents.Save(doc);

            return RedirectToAction("Index", "Document");
        }

The exception is displayed in Context.Documents.Save(doc); --> The specified method is not supported

Answer 1

MongoGridFSFileInfo is not a POCO class. What I mean by that is that it has many properties on it that either aren't persistable or shouldn't be.

The only thing you actually need to persist to get back a document is the unique identifier for the file. You may want to persist some other meta-data as well, but only the identifier is required.