Revit API 2012: Revoke Saving Using Events in External DB Application (IExternalDBApplication)

Revit API 2012 provides one more application type, IExternalDBApplication, which is supposed to help do some DB stuffs at Revit startup, monitor some document events, and so on. In this post, we are going to see how to revoke Document Save related operations using events in an External DB Application (IExternalDBApplication).

It is obvious that the DocumentSaving and the DocumentSavingAs document events need to be lisented to in the OnStartup point as follows:

_cachedCtrlApp.DocumentSaving += new EventHandler<DocumentSavingEventArgs>(_cachedCtrlApp_DocumentSaving);
_cachedCtrlApp.DocumentSavingAs += new EventHandler<DocumentSavingAsEventArgs>(_cachedCtrlApp_DocumentSavingAs);

Then we can implement the event handlers like:

        void _cachedCtrlApp_DocumentSavingAs(object sender, DocumentSavingAsEventArgs e)
        {
            if (e.Cancellable && e.Document.PathName.ToLower() == "c:\\temp\\cannotsave.rvt")
            {
                MessageBox.Show("The model cannot be saved!");
                e.Cancel();
            }
        }

        void _cachedCtrlApp_DocumentSaving(object sender, DocumentSavingEventArgs e)
        {
            if (e.Cancellable && e.Document.PathName.ToLower() == "c:\\temp\\cannotsave.rvt")
            {
                MessageBox.Show("The model cannot be saved!");
                e.Cancel();
            }
        }

Then whenever a document is going to be saved or saved as, the document path will be checked and if it’s the particular model of concern, the Save or Save As operation will be revoked.
 
Here is the whole implementation of the IExternalDBApplication for convenience:

#region Namespaces

using System;
using System.Text;
using System.Linq;
using System.Xml;
using System.Reflection;
using System.ComponentModel;
using System.Collections;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media.Imaging;
using System.Windows.Forms;
using System.IO;

using Autodesk.Revit.ApplicationServices;
using Autodesk.Revit.Attributes;

using Autodesk.Revit.DB;
using Autodesk.Revit.DB.Events;
using Autodesk.Revit.DB.Architecture;
using Autodesk.Revit.DB.Structure;
using Autodesk.Revit.DB.Mechanical;
using Autodesk.Revit.DB.Electrical;
using Autodesk.Revit.DB.Plumbing;

using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;
using Autodesk.Revit.UI.Events;

using Autodesk.Revit.Collections;
using Autodesk.Revit.Exceptions;
using Autodesk.Revit.Utility;

using RvtApplication = Autodesk.Revit.ApplicationServices.Application;
using RvtDocument = Autodesk.Revit.DB.Document;

#endregion

namespace RevitAddinCS1
{
    [Transaction(TransactionMode.Manual)]
    [Regeneration(RegenerationOption.Manual)]
    public class ExtDbApp : IExternalDBApplication
    {
        #region Cached Variables

        public static ControlledApplication _cachedCtrlApp;
        
        #endregion

        #region IExternalApplication Members

        public ExternalDBApplicationResult OnStartup(ControlledApplication ctrlApp)
        {
            try
            {
                _cachedCtrlApp = ctrlApp;

                //TODO: add you code below.
                //MessageBox.Show("ExtDbApp");

                _cachedCtrlApp.DocumentCreated += new EventHandler<DocumentCreatedEventArgs>(_cachedCtrlApp_DocumentCreated);

                _cachedCtrlApp.DocumentOpened += new EventHandler<DocumentOpenedEventArgs>(_cachedCtrlApp_DocumentOpened);
                _cachedCtrlApp.DocumentClosed += new EventHandler<DocumentClosedEventArgs>(_cachedCtrlApp_DocumentClosed);

                _cachedCtrlApp.DocumentSaving += new EventHandler<DocumentSavingEventArgs>(_cachedCtrlApp_DocumentSaving);
                _cachedCtrlApp.DocumentSavingAs += new EventHandler<DocumentSavingAsEventArgs>(_cachedCtrlApp_DocumentSavingAs);

                return ExternalDBApplicationResult.Succeeded;
            }
            catch (Exception ex)
            {
                MessageBox.Show( ex.ToString() );
                return ExternalDBApplicationResult.Failed;
            }
        }

        void _cachedCtrlApp_DocumentSavingAs(object sender, DocumentSavingAsEventArgs e)
        {
            if (e.Cancellable && e.Document.PathName.ToLower() == "c:\\temp\\cannotsave.rvt")
            {
                MessageBox.Show("The model cannot be saved!");
                e.Cancel();
            }
        }

        void _cachedCtrlApp_DocumentSaving(object sender, DocumentSavingEventArgs e)
        {
            if (e.Cancellable && e.Document.PathName.ToLower() == "c:\\temp\\cannotsave.rvt")
            {
                MessageBox.Show("The model cannot be saved!");
                e.Cancel();
            }
        }

        void _cachedCtrlApp_DocumentClosed(object sender, DocumentClosedEventArgs e)
        {
            using (StreamWriter sw = new StreamWriter(@"c:\temp\RevitLogOpenClose.txt", true))
            {  
                sw.WriteLine(DateTime.Now.ToString() + " : The document with #" + e.DocumentId.ToString() + " was closed.");
            }
        }

        void _cachedCtrlApp_DocumentOpened(object sender, DocumentOpenedEventArgs e)
        {
            using (StreamWriter sw = new StreamWriter(@"c:\temp\RevitLogOpenClose.txt", true))
            {
                sw.WriteLine(DateTime.Now.ToString() + " : The document " + e.Document.PathName + " was opened.");
            }
        }

        void _cachedCtrlApp_DocumentCreated(object sender, DocumentCreatedEventArgs e)
        {
            Document doc = e.Document;
            ElementId id = ElementId.InvalidElementId;

            using (Transaction tr = new Transaction(doc, "Hello from RevitAddinWizard."))
            {
                tr.Start();

                TextNote text = doc.Create.NewTextNote(
                    doc.ActiveView,
                    new XYZ(0, 0, 0),
                    new XYZ(1, 0, 0),
                    new XYZ(0, 0, 1),
                    2,
                    TextAlignFlags.TEF_ALIGN_CENTER,
                    "Hello from RevitAddinWizard.");
                text.Width = 20;

                tr.Commit();
                id = text.Id;
            }
        }

        public ExternalDBApplicationResult OnShutdown(ControlledApplication ctlApp)
        {
            try
            {

                return ExternalDBApplicationResult.Succeeded;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
                return ExternalDBApplicationResult.Failed;
            }
        }

        #endregion       
    }
}

Revit Addin Wizard (RevitAddinWizard) is going to provide an External DB Application wizard to help implement the IExternalDBApplication interface automatically and reliably. With the assistance of the External DB Application wizard and some event wizards, the above code can be created conveniently in a minute.