Catching a built in warning from Revit (not addin) and selecting an option

[EATREVITPOOPCAD]

I am not sure if this is possible, but would like to ask before putting a nail in this coffin...

In Revit, if you EQ/EQ constrain elements via a dimension string, and then delete that dimension string - you get this warning.

Is it possible via API to 'listen' for this warning to show up, and hit Unconstrain by default?

[jeremy_tammik · Accepted solution]

I am pretty optimistic that that can be achieved using the Failure API. You can read all about that and other methods for catching and handling dialogues and errors in The Building Coder topic group:

https://thebuildingcoder.typepad.com/blog/about-the-author.html#5.32

I see lots of similar previous discussions here in the forum searching for "handle warning". Here is one of them which includes some sample code that may or may not fit your needs:

https://forums.autodesk.com/t5/revit-api-forum/error-handling-resolution-options/m-p/10480617

[EATREVITPOOPCAD]

Thank you so much @jeremy_tammik for pointing in the right direction and carrying over some of the optimism 🙂 Will post my results/progress here

[EATREVITPOOPCAD]

#region Namespaces
using Autodesk.Revit.ApplicationServices;
using Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.DB.Events;
using Autodesk.Revit.UI;
using System;
using System.Collections.Generic;
#endregion

namespace Unconstrain_Dim_Delete
{
    internal class App : IExternalApplication
    {
        public Result OnStartup(UIControlledApplication a)
        {
            a.ControlledApplication.ApplicationInitialized += ApplicationInitialized;
            return Result.Succeeded;
        }

        private void ApplicationInitialized(object sender, ApplicationInitializedEventArgs e)
        {
            /* 
             * DOES NOT WORK BUT THAT IS THE GUID OF MY COMMAND....
             * 
             * https://thebuildingcoder.typepad.com/blog/2013/10/programmatic-custom-add-in-external-command-launch.html
             * 
            UIApplication uiapp = sender as UIApplication;
            RevitCommandId cmdID = RevitCommandId.LookupCommandId("5d5ddf79-db55-49fb-83f1-0337a30c9ee0");
            uiapp.PostCommand(cmdID);
            *
            */

            var command = new Command();

            //I never remember if the sender is Application or UIApplication
            if (sender is UIApplication)
                command.Execute(sender as UIApplication);
            else
                command.Execute(new UIApplication(sender as Application));
        }

        public Result OnShutdown(UIControlledApplication a)
        {
            return Result.Succeeded;
        }
    }   // END OF IE APP

    [Transaction(TransactionMode.Manual)]
    [Regeneration(RegenerationOption.Manual)]
    public class Command : IExternalCommand
    {
        public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
        {
            return Execute(commandData.Application);
        }

        public Result Execute(UIApplication a)
        {
            a.Application.FailuresProcessing += new EventHandler<FailuresProcessingEventArgs>(OnFailuresProcessing);

            return Result.Succeeded;
        }

        private void OnFailuresProcessing(object sender,FailuresProcessingEventArgs e)
        {
            FailuresAccessor failuresAccessor = e.GetFailuresAccessor();

            String transactionName = failuresAccessor.GetTransactionName();

            IList<FailureMessageAccessor> fmas = failuresAccessor.GetFailureMessages();

            if (fmas.Count == 0)
            {
                // FailureProcessingResult.Continue is to let the failure cycle continue next step.
                e.SetProcessingResult(FailureProcessingResult.Continue);

                return;
            }

            // If manually delete an element, the transaction name is 'Delete Selection' if the failure is caused by deleting element.
            if (transactionName.Equals("Delete Selection"))
            {
                string keyWords = "A dimension that has EQ constraints is being deleted, but the elements will still be constrained.";
                string fmaDescription = "";

                foreach (FailureMessageAccessor fma in fmas)
                {
                    fmaDescription = fma.GetDescriptionText();
                    failuresAccessor.ResolveFailure(fma);       
                }

                if (fmaDescription.Contains(keyWords))
                    e.SetProcessingResult(FailureProcessingResult.ProceedWithCommit);

                return;
            }

            e.SetProcessingResult(FailureProcessingResult.Continue);
        }       
    }           // END OF IE COMMAND
}               // END OF NAMESPACE

So I got it to work, probably not the cleanest way. I couldn't figure out how to do this using just 

IExternalApplication or IExternalCommand, so ended up using both and not registering the IExternalCommand in the .addin file... IExternalCommand has ExternalCommandData with the UIApplication and IExternalApplication allows starting code when Revit is initialized. 

Also not sure what I was doing wrong, but I could not PostCommand() either... I had the external command registered in the .addin file and I followed this article:

https://thebuildingcoder.typepad.com/blog/2013/10/programmatic-custom-add-in-external-command-launch...

Either way seems to work well, and I am curious if my coworkers notice any performance issues.