Error messages in ProgressBox background job

Question

I am creating a custom command and want to handle exceptions in a userfriendly way, i.e. display an errormessage.

This is the code for my command:

public class ImportCommand : Command
{
    private readonly ICommandArgFactory _commandArgFactory;

    public ImportCommand(ICommandArgFactory commandArgFactory)
    {
        if (commandArgFactory == null) throw new ArgumentNullException(nameof(commandArgFactory));
        _commandArgFactory = commandArgFactory;
    }

    public override void Execute(CommandContext context)
    {
        NameValueCollection parameters = _commandArgFactory.GetArgs(context);

        Sitecore.Context.ClientPage.Start(this, "Import", new ClientPipelineArgs(parameters));
    }

    private void Import(ClientPipelineArgs args)
    {
        if (args.IsPostBack)
        {
            if (args.Result == "no") return;

            ProgressBox.Execute("Import", "Import", DoImport, args);
            SheerResponse.Alert("Import done!");
        }
        else
        {
            SheerResponse.Confirm("Are you sure?");
            args.WaitForPostBack();
        }
    }

    private void DoImport(object[] parameters)
    {
        BaseJob job = Sitecore.Context.Job;

        try
        {
            ClientPipelineArgs args = parameters[0] as ClientPipelineArgs;

            job.Status.State = JobState.Running;
            ...code here...
            job.Status.AddMessage("Parsing some more...");
            job.Status.State = JobState.Finished;
        }
        catch (CustomException ex)
        {
            Log.Error(mcxmfe.Message, this);
            job.Status.State = JobState.Finished;
            Sitecore.Context.ClientPage.SendMessage(this, mcxmfe.Message);
        }
        catch (Exception ex)
        {
            Log.Error(ex.Message, this);
            job.Status.State = JobState.Finished;
        }
    }
}

However, when my CustomException gets thrown, the code that I was hoping would print an error message in a popup also throws an error:

Sitecore.Context.ClientPage.SendMessage(this, mcxmfe.Message);

I've tried using SheerResponse.Alert(...) but that gives a NullReferenceException with the following stacktrace:

   at Sitecore.Web.UI.Sheer.ClientPage..ctor(HttpContextBase httpContext)
   at Sitecore.Context.get_ClientPage()
   at Sitecore.Web.UI.Sheer.SheerResponse.Alert(String text, String[] arguments)
   at [CustomCode]

I've also tried using Sitecore.Context.ClientPage.ClientResponse(...) but that also gave me a NullReferenceException with the following stacktrace:

   at Sitecore.Web.UI.Sheer.ClientPage..ctor(HttpContextBase httpContext)
   at Sitecore.Context.get_ClientPage()
   at [CustomCode]

How do I show an alert, when the exception is thrown in a background task?

Answer 1

In the background the ProgressBox.Execute() is running the given method as a job where you don't have SheerResponse or ClientResponse.

Try the following:

• add job.Status.Failed = true; when you handling the exception
• use ProgressBox.Execute("Import", "Import", "<icon>", DoImport, "Something went wrong...", args); instead of ProgressBox.Execute("Import", "Import", DoImport, args);

The changes above should render the "Something went wrong..." text instead of the exception. This solution only good enough for you if you can display the same message when an error occurs.

Answer 2

This answer from Tamas led me down the right path, so I will mark that answer as the solution.

It seems that if you use job.Status.Failed = true together with job.Status.LogError("exception message"), the exception message will actually be displayed in a popup. Let me demonstrate:

public class ImportCommand : Command
{
    private readonly ICommandArgFactory _commandArgFactory;

    public ImportCommand(
        ICommandArgFactory commandArgFactory
    {
        if (commandArgFactory == null) throw new ArgumentNullException(nameof(commandArgFactory));
        _commandArgFactory = commandArgFactory;
    }

    public override void Execute(CommandContext context)
    {
        NameValueCollection parameters = _commandArgFactory.GetArgs(context);

        Sitecore.Context.ClientPage.Start(this, "Import", new ClientPipelineArgs(parameters));
    }

    private void Import(ClientPipelineArgs args)
    {
        if (args.IsPostBack)
        {
            if (args.Result == "no") return;

            ProgressBox.Execute("Import", "Import", DoImport, args);
        }
        else
        {
            SheerResponse.Confirm("Are you sure?");
            args.WaitForPostBack();
        }
    }

    private void DoImport(object[] parameters)
    {
        BaseJob job = Sitecore.Context.Job;

        if (job == null) return;

        try
        {
            ClientPipelineArgs args = parameters[0] as ClientPipelineArgs;

            job.Status.State = JobState.Running;
            ...code here...
            job.Status.AddMessage("Parsing some more...");
            job.Status.State = JobState.Finished;
        }
        catch (CustomException customEx)
        {
            Log.Error(customEx.Message, this);
            job.Status.LogError(customEx.Message);
            job.Status.Failed = true;
        }
        catch (Exception ex)
        {
            Log.Error(ex.Message, this);
            job.Status.LogError(ex.Message);
            job.Status.Failed = true;
        }
    }
}