DYN-7400 : handle host data marshaler dependent on python runtime (#15537)

Co-authored-by: Bogdan Zavu <[email protected]>

Author: BogdanZavu

src/Libraries/DSCPython/CPythonEvaluator.cs

@@ -447,6 +447,46 @@ private static string GetTraceBack(Exception e)
 
         #region Marshalling
 
+        /// <summary>
+        /// Add additional data marshalers to handle host data.
+        /// </summary>
+        [SupressImportIntoVM]
+        internal override void RegisterHostDataMarshalers()
+        {
+            DataMarshaler dataMarshalerToUse = HostDataMarshaler as DataMarshaler;
+            dataMarshalerToUse?.RegisterMarshaler((PyObject pyObj) =>
+            {
+                try
+                {
+                    using (Py.GIL())
+                    {
+                        if (PyDict.IsDictType(pyObj))
+                        {
+                            using (var pyDict = new PyDict(pyObj))
+                            {
+                                var dict = new PyDict();
+                                foreach (PyObject item in pyDict.Items())
+                                {
+                                    dict.SetItem(
+                                        ConverterExtension.ToPython(dataMarshalerToUse.Marshal(item.GetItem(0))),
+                                        ConverterExtension.ToPython(dataMarshalerToUse.Marshal(item.GetItem(1)))
+                                    );
+                                }
+                                return dict;
+                            }
+                        }
+                        var unmarshalled = pyObj.AsManagedObject(typeof(object));
+                        return dataMarshalerToUse.Marshal(unmarshalled);
+                    }
+                }
+                catch (Exception e)
+                {
+                    DynamoLogger?.Log($"error marshaling python object {pyObj.Handle} {e.Message}");                    
+                    return pyObj;
+                }
+            });
+        }
+
         /// <summary>
         ///     Data Marshaler for all data coming into a Python node.
         /// </summary>

src/NodeServices/Properties/AssemblyInfo.cs

@@ -44,3 +44,4 @@
 [assembly: InternalsVisibleTo("DynamoApplications")]
 [assembly: InternalsVisibleTo("DynamoUnits")]
 [assembly: InternalsVisibleTo("DSPythonNet3")]
+[assembly: InternalsVisibleTo("DynamoRevitDS")]

src/NodeServices/PythonServices.cs

@@ -63,6 +63,13 @@ public abstract object OutputDataMarshaler
             get;
         }
 
+        /// <summary>
+        /// Data marshaler for host data used during the execution of a Python node.
+        /// This can be implemented differently across various Python engines due to
+        /// factors such as differing PythonNet APIs or other specific requirements.
+        /// </summary>
+        internal object HostDataMarshaler { get; set; }
+
         /// <summary>
         /// Name of the Python engine
         /// </summary>
@@ -93,6 +100,14 @@ public abstract string Name
         public abstract object Evaluate(string code,
                         IList bindingNames,
                         [ArbitraryDimensionArrayImport] IList bindingValues);
+
+        /// <summary>
+        /// Add additional data marshalers to handle host data.
+        /// While some data marshalers are specific to the host application,
+        /// they must be implemented at the Dynamo Core level in order to
+        /// avoid host dependencies on the Python runtime.
+        /// </summary>
+        internal virtual void RegisterHostDataMarshalers() { }
     }
 
     /// <summary>