Ninja Snacks Tales From the Enterprise

Automatic Exception Reporting with YouTrack and Nancy pt. 1: The Skeleton

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Getting the business users to try and recreate a bug is difficult to say the least. They may not remember what it is they did to reproduce. But you can bet that if you don't fix it by yesterday you're gonna get an earful. In fact we just did. This is me doing something about it :)

Turns out this is annoyingly easy with Nancy and the YouTrackSharp library, so easy that I'm not going to bother test driving this. Frankly writing this post took longer than the actual code. First, the Bootstrapper:

public class Bootstrapper : DefaultNancyBootstrapper
{
    protected override void ConfigureApplicationContainer(TinyIoc.TinyIoCContainer container)
    {
        base.ConfigureApplicationContainer(container);

        var connection = new Connection("localhost", port: 8085);
        connection.Authenticate("application", "abc123");

        container.Register<IConnection>(connection);
    }
}

I am unsure if a Connection is better served by a PerRequest lifestyle. I believe underneath it uses a cookie, which can expire. So maybe.

Next up is the viewmodel. Note the casting operator:

public class ReportExceptionViewModel
{
    public string ExceptionDetail { get; set; }
    public string ExceptionType { get; set; }
    public string UserId { get; set; }
    public string Notes { get; set; }
    public Uri Location { get; set; }
    public string RequestEntity { get; set; }
    public string ProjectId { get; set; }

    public static implicit operator Issue(ReportExceptionViewModel viewModel)
    {
        dynamic issue = new Issue();

        issue.Project = viewModel.ProjectId;
        issue.Summary = viewModel.Location + " - " + viewModel.ExceptionType;
        issue.Description = new StringBuilder()
            .Append(viewModel.ExceptionDetail)
            .AppendLine().AppendLine()
            .AppendLine(viewModel.Notes)
            .AppendLine().AppendLine()
            .AppendLine("Environment:")
            .AppendLine(viewModel.UserId)
            .AppendLine(viewModel.RequestEntity)
            .ToString();

        return issue;
    }
}

I'll explain more about the casting operator in a second.

What's up with that dynamic? Issues in YouTrack are really really flexible. You can attach an arbitrary set of fields to them. dynamic is a perfect fit, then.

Finally we have the NancyModule:

public class IssuesModule : NancyModule
{
    public IssuesModule(IssueManagement issues)
        : base("/issues")
    {
        Get["/report-exception"] = p =>
        {
            var model = this.Bind<ReportExceptionViewModel>();
            return Negotiate.WithModel(model);
        };

        Post["/report-exception"] = p =>
        {
            var model = this.Bind<ReportExceptionViewModel>();

            Issue issue = model;

            issues.CreateIssue(issue);

            return 200;
        };
    }
}

At this stage the GET isn't stricly necessary - we have no view so there's no form to display. I mostly have it in there to make sure that nancy properly binds the ReportExceptionViewModel. This is easy with the built in conneg - just append .json to the url and you are good to go. Nancy will happily take your query string, merge it with your POST if it is application/x-www-form-urlencoded and turn that into a flat DTO for you, just like PHP.

    Testing it out with Advanced Rest Client    
Testing it out with Advanced Rest Client

You'll also notice there's hardly any code in the Module. That's why I moved all that ugly object mapping into a casting operator. It'll keep our Module nice and clean.

    The results    
The results

That's more or less it! You can easily wire this up in Silverlight, $.ajax, etc. But IMO this is not suitable for a real web application. As a user I'd want a link to check up on this. As a developer I would like to wire this right into Nancy's status code / error handling mechanism. Next time we'll look at making this a bit more RESTful.

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