Read classification attached to an object using VBA or VB.NET?

[jan]

Does anyone know how to read classifications attached to objects using VB.NET or VBA?

I have an entire MEP project with lots and lots of MEP-objects. A classification definition that applies to the MEP objects exist in each drawing and every objects have a certain classification code.

What I need to do is to attach one specific propertyset to each MEP object. That is the easy part ... However which propertyset to attach depends on the classification code attached to the object. That is the tricky part!

The attached image refers to a wall object, but the issue is the same with MEP objects.

... hope that someone can help with this.

Regards

Jan Grenov

[Keith.Brown]

This is the method that I use to return a classification from an object.  This is part of a larger class so some of the variables are properties of the class.

Sorry, i don't code in VB.Net anymore.  You can convert from C# using one of the many converters available online.

code = C#

      public Classification GetClassificationOnGeo(Geo geo)
        {
            try
            {
                using (var transaction = _database.TransactionManager.TopTransaction)
                {
                    if (transaction == null)
                    {
                        throw new Autodesk.AutoCAD.Runtime.Exception(ErrorStatus.NoActiveTransactions);
                    }

                    var dictionaryClassificationDefinition = new DictionaryClassificationDefinition(_database);
                    ObjectIdCollection objectIds = dictionaryClassificationDefinition.Records;
                    foreach (ObjectId objId in objectIds)
                    {
                        using (
                            var classificationDefinition =
                                transaction.GetObject(objId, OpenMode.ForRead) as ClassificationDefinition)
                        {
                            if (classificationDefinition != null)
                            {
                                if (classificationDefinition.Name.Equals(_styleName, StringComparison.OrdinalIgnoreCase))
                                {
                                    ObjectId classificationDefinitionId = classificationDefinition.ObjectId;
                                    using (
                                        var classification =
                                            transaction.GetObject(
                                                ClassificationDefinition.GetClassification(geo,
                                                    classificationDefinitionId), OpenMode.ForRead) as Classification)
                                    {
                                        if (classification != null)
                                        {
                                            return classification;
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                return null;
            }
            catch (Exception)
            {
                return null;
            }
        }

You can modify that method to be more generic and returning the name of the classification by doing something like this:

        public string GetClassificationOnGeo(Database database, Geo geo, string styleName)
        {
            try
            {
                using (var transaction = database.TransactionManager.TopTransaction)
                {
                    if (transaction == null)
                    {
                        throw new Autodesk.AutoCAD.Runtime.Exception(ErrorStatus.NoActiveTransactions);
                    }

                    var dictionaryClassificationDefinition = new DictionaryClassificationDefinition(database);
                    ObjectIdCollection objectIds = dictionaryClassificationDefinition.Records;
                    foreach (ObjectId objId in objectIds)
                    {
                        using (
                            var classificationDefinition =
                                transaction.GetObject(objId, OpenMode.ForRead) as ClassificationDefinition)
                        {
                            if (classificationDefinition != null)
                            {
                                if (classificationDefinition.Name.Equals(styleName, StringComparison.OrdinalIgnoreCase))
                                {
                                    ObjectId classificationDefinitionId = classificationDefinition.ObjectId;
                                    using (
                                        var classification =
                                            transaction.GetObject(
                                                ClassificationDefinition.GetClassification(geo,
                                                    classificationDefinitionId), OpenMode.ForRead) as Classification)
                                    {
                                        if (classification != null)
                                        {
                                            transaction.commit();
                                            return classification.name;
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                return string.Empty;
            }
            catch (Exception)
            {
                return string.Empty;
            }
        }

[Keith.Brown · Accepted solution]

There was an error in the first block of code that I posted.

I had wrapped transaction to get the classification of the object inside a using statement.  When I returned the classification it went out of scope and then became null.  the using statement should be removed and let the calling function deal with the disposal of the classification.

The new code becomes:

      public Classification GetClassificationOnGeo(Geo geo)
        {
            try
            {
                using (var transaction = _database.TransactionManager.TopTransaction)
                {
                    if (transaction == null)
                    {
                        throw new Autodesk.AutoCAD.Runtime.Exception(ErrorStatus.NoActiveTransactions);
                    }

                    var dictionaryClassificationDefinition = new DictionaryClassificationDefinition(_database);
                    ObjectIdCollection objectIds = dictionaryClassificationDefinition.Records;
                    foreach (ObjectId objId in objectIds)
                    {
                        using (
                            var classificationDefinition =
                                transaction.GetObject(objId, OpenMode.ForRead) as ClassificationDefinition)
                        {
                            if (classificationDefinition != null)
                            {
                                if (classificationDefinition.Name.Equals(_styleName, StringComparison.OrdinalIgnoreCase))
                                {
                                    ObjectId classificationDefinitionId = classificationDefinition.ObjectId;
                                    var classification = transaction.GetObject( ClassificationDefinition.GetClassification( geo,classificationDefinitionId ), OpenMode.ForRead ) as Classification);
                                    if (classification != null)
                                    {
                                        return classification;
                                    }
                                }
                            }
                        }
                    }
                }
                return null;
            }
            catch (Exception)
            {
                return null;
            }
        }

[jan]

Thanks Keith

I am having no trouble with reading C# so that will do just fine.
I will try out your code and let you know how it goes.

🙂

[jan · Accepted solution]

Hi Keith

It worked just fine 🙂 Thanks a lot. This really was a great help!

Here is my code as it looks in VB.NET:

Public Function GetClassificationOnGeo(Geo As Geo) As Classification

  Dim db As Database = Geo.Database

  Try

    Using tr As Transaction = db.TransactionManager.TopTransaction

      If tr IsNothingThen

        ThrowNew Autodesk.AutoCAD.Runtime.Exception(Autodesk.AutoCAD.Runtime.ErrorStatus.NoActiveTransactions)

      EndIf

      Dim dictClsDef AsNew DictionaryClassificationDefinition(db)

      Dim objectIds As ObjectIdCollection = dictClsDef.Records

      ForEach objId As ObjectId In objectIds

        Using clsDef As ClassificationDefinition = tr.GetObject(objId, OpenMode.ForRead)

          If clsDef IsNotNothingThen

            If clsDef.Name.Equals("AAU_SfbClassification", StringComparison.OrdinalIgnoreCase) Then

              Dim classificationDefinitionId As ObjectId = clsDef.ObjectId

              Dim clf As Classification = tr.GetObject(ClassificationDefinition.GetClassification(Geo, classificationDefinitionId), OpenMode.ForRead)

              If clf IsNotNothingThen

                Return clf

              EndIf

            EndIf

          EndIf

        End Using

      Next

     End Using

   Catch ex As System.Exception

     Return Nothing

   End Try

  'If the function reaches this point ...

  Return Nothing

End Function

Regards

Jan Grenov

[joluinfante]

Hi!

I'm trying to compile a c# with "new DictionaryClassificationDefinition(db)", but, I have this error message:

"No se puede encontrar el tipo o el nombre de espacio de nombre 'DictionaryClassificationDefinition'.

Can you tell me the "using directives" to build it?