Clearing MongoDb keys on IIS website

Question

New to IIS and Mongo, and I'm trying to find a way to clear the keys from my server to avoid an "item with the same key has already been added" exception.

IMongoDatabase _db;
IMongoCollection<BoardStorageItem> _boardsCollection;
public MongoDb()
    {
        var client = new MongoClient("mongodb://localhost");
        _db = client.GetDatabase("KanbanDemonstration");

        BsonClassMap.RegisterClassMap<CardStorageItem>();
        BsonClassMap.RegisterClassMap<ColumnStorageItem>();
        BsonClassMap.RegisterClassMap<BoardStorageItem>();
        BsonClassMap.RegisterClassMap<EmployeeStorageItem>();


        _boardsCollection = _db.GetCollection<BoardStorageItem>("Board");
    }

    public BoardStorageItem GetBoardByName(string name)
    {
        var board = _boardsCollection.AsQueryable().FirstOrDefault(b => b.Name == name);
        return board;
    }

public class MongoConverter
{
    MongoDb _mongoDb;

    public MongoConverter()
    {
        _mongoDb = new MongoDb();
    }

    public BoardStorageItem GetBoardByName(string name)
    {
        return _mongoDb.GetBoardByName(name);
    }
}

and then for the code on the web page itself

protected void Button1_Click(object sender, EventArgs e)
{
    _mongoConverter = new MongoConverter();
    var board = _mongoConverter.GetBoardByName(TextBox1.Text);

    BoardName = board.Name;
    BoardId = board.Id;

    Label3.Text = BoardName;
    Label4.Text = BoardId;

    Session.Clear();
}

This works perfectly this first time I use the button to get a board, but if I try a second time, I get an exception "item with the same key has already been added" when attempting to new up MongoConverter. I had thought that clearing the session after would clear out the keys as well, but the only thing that seems to work is resetting the server itself.

Answer 1

Calling BsonClassMap.RegisterClassMap<T>() should only be done once per type. And it should be done at application startup, before opening any database connections according to the documentation .

Since you're in ASP.NET, put this in your Application_Start event in your global application class (global.asax)

void Application_Start(object sender, EventArgs e)
{
    BsonClassMap.RegisterClassMap<CardStorageItem>();
    BsonClassMap.RegisterClassMap<ColumnStorageItem>();
    BsonClassMap.RegisterClassMap<BoardStorageItem>();
    BsonClassMap.RegisterClassMap<EmployeeStorageItem>();
}

You can make another method that calls it so you don't pollute your global application class if you want. And of course, remove the registrations from your constructor.