Remove OptionalPlaceHolders on NodeState Instances

Stack/Opc.Ua.Types/State/BaseInstanceState.cs

@@ -47,6 +47,9 @@ protected BaseInstanceState(NodeClass nodeClass, NodeState parent)
             Parent = parent;
         }
 
+        /// <inheritdoc/>
+        protected override bool RemovePlaceholderChildrenOnCreate => true;
+
         /// <summary>
         /// Initializes the instance from another instance.
         /// </summary>

Stack/Opc.Ua.Types/State/NodeState.cs

@@ -2710,6 +2710,11 @@ public virtual void Create(
         {
             Initialize(context);
 
+            if (RemovePlaceholderChildrenOnCreate)
+            {
+                RemovePlaceholderChildren(context);
+            }
+
             // Call OnBeforeCreate on all children.
             CallOnBeforeCreate(context);
 
@@ -2819,13 +2824,88 @@ public virtual void Create(ISystemContext context, NodeState source)
         {
             Initialize(context, source);
 
+            if (RemovePlaceholderChildrenOnCreate)
+            {
+                RemovePlaceholderChildren(context);
+            }
+
             CallOnBeforeCreate(context);
 
             CallOnAfterCreate(context, null);
 
             ClearChangeMasks(context, true);
         }
 
+        /// <summary>
+        /// Whether placeholder declarations should be removed during runtime creation.
+        /// </summary>
+        protected virtual bool RemovePlaceholderChildrenOnCreate => false;
+
+        /// <summary>
+        /// Removes instantiated placeholder declarations from runtime instances.
+        /// </summary>
+        private void RemovePlaceholderChildren(ISystemContext context)
+        {
+            var children = new List<BaseInstanceState>();
+            GetChildren(context, children);
+
+            for (int ii = 0; ii < children.Count; ii++)
+            {
+                BaseInstanceState child = children[ii];
+
+                if (IsPlaceholderChild(child))
+                {
+                    RemoveChild(child);
+
+                    if (ReferenceEquals(child.Parent, this))
+                    {
+                        child.Parent = null;
+                    }
+
+                    continue;
+                }
+
+                child.RemovePlaceholderChildren(context);
+            }
+        }
+
+        /// <summary>
+        /// Returns true if the child represents a placeholder declaration.
+        /// </summary>
+        private static bool IsPlaceholderChild(BaseInstanceState child)
+        {
+            if (child.ModellingRuleId == ObjectIds.ModellingRule_OptionalPlaceholder ||
+                child.ModellingRuleId == ObjectIds.ModellingRule_MandatoryPlaceholder)
+            {
+                return true;
+            }
+
+            string browseName = child.BrowseName?.Name;
+
+            // Some generated placeholder declarations reach runtime without their
+            // placeholder modelling rule; the fallback is limited to model-defined
+            // standard nodes that still carry the generated <PlaceholderName>
+            // browse-name form.
+            return IsGeneratedStandardNumericNode(child) &&
+                browseName != null &&
+                browseName.Length > 1 &&
+                browseName[0] == '<' &&
+                browseName[browseName.Length - 1] == '>';
+        }
+
+        /// <summary>
+        /// Returns true if the child still has its generated standard numeric node identity.
+        /// </summary>
+        private static bool IsGeneratedStandardNumericNode(BaseInstanceState child)
+        {
+            return child.NumericId != 0 &&
+                child.NodeId != null &&
+                child.NodeId.NamespaceIndex == 0 &&
+                child.NodeId.IdType == IdType.Numeric &&
+                child.NodeId.Identifier is uint identifier &&
+                identifier == child.NumericId;
+        }
+
         /// <summary>
         /// Deletes an instance and its children (calls OnStateChange callback for each node).
         /// </summary>

Tests/Opc.Ua.Core.Tests/Stack/State/NodeStateTests.cs

@@ -28,6 +28,7 @@
  * ======================================================================*/
 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using NUnit.Framework;
@@ -84,10 +85,87 @@ public void ActivateNodeStateType(Type systemType)
             Assert.NotNull(testObject);
             var context = new SystemContext(telemetry) { NamespaceUris = Context.NamespaceUris };
             Assert.AreEqual(0, context.NamespaceUris.GetIndexOrAppend(OpcUa));
+
             testObject.Create(context, new NodeId(1000), "Name", "DisplayName", true);
             testObject.Dispose();
         }
 
+        /// <summary>
+        /// Instantiate NodeState types across Opc.Ua assemblies and fail on placeholder children.
+        /// </summary>
+        [Test]
+        public void NodeStateTypesAcrossOpcUaAssemblies_ShouldNotInstantiatePlaceholderChildren()
+        {
+            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
+            var context = new SystemContext(telemetry) { NamespaceUris = Context.NamespaceUris };
+            var placeholders = new List<string>();
+            uint nodeId = 200000;
+            Type[] nodeStateTypesToScan = [.. GetOpcUaNodeStateTypes().OrderBy(type => type.FullName)];
+
+            foreach (Type systemType in nodeStateTypesToScan)
+            {
+                var testObject = CreateDefaultNodeStateType(systemType) as NodeState;
+
+                if (testObject == null)
+                {
+                    continue;
+                }
+
+                if (testObject is not BaseInstanceState)
+                {
+                    testObject.Dispose();
+                    continue;
+                }
+
+                try
+                {
+                    testObject.Create(context, new NodeId(nodeId++), "Name", "DisplayName", true);
+                    CollectInstantiatedPlaceholders(
+                        context,
+                        testObject,
+                        systemType.Assembly.GetName().Name,
+                        systemType.FullName,
+                        placeholders);
+                }
+                finally
+                {
+                    testObject.Dispose();
+                }
+            }
+
+            Assert.That(
+                placeholders,
+                Is.Empty,
+                "Instantiated placeholder children were found:" + Environment.NewLine +
+                string.Join(Environment.NewLine, placeholders));
+        }
+
+        /// <summary>
+        /// Verify placeholder declarations remain available on type definitions.
+        /// </summary>
+        [Test]
+        public void TypeDefinitions_ShouldKeepPlaceholderChildren()
+        {
+            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
+            var context = new SystemContext(telemetry) { NamespaceUris = Context.NamespaceUris };
+            var typeDefinition = new BaseObjectTypeState();
+            var placeholder = new BaseObjectState(typeDefinition)
+            {
+                BrowseName = new QualifiedName("<OptionalChild>", 0),
+                DisplayName = "<OptionalChild>",
+                ModellingRuleId = ObjectIds.ModellingRule_OptionalPlaceholder
+            };
+
+            typeDefinition.AddChild(placeholder);
+
+            typeDefinition.Create(context, new NodeId(1000), "TypeName", "TypeName", true);
+
+            var children = new List<BaseInstanceState>();
+            typeDefinition.GetChildren(context, children);
+
+            Assert.That(children, Has.Member(placeholder));
+        }
+
         /// <summary>
         /// Create an instance of a NodeState type with default values.
         /// </summary>
@@ -149,6 +227,132 @@ private static bool IsNodeStateType(Type systemType)
 
             return CreateDefaultNodeStateType(systemType) is NodeState;
         }
+
+        /// <summary>
+        /// Recursively collect instantiated placeholder children for diagnostics.
+        /// </summary>
+        private static void CollectInstantiatedPlaceholders(
+            ISystemContext context,
+            NodeState nodeState,
+            string ownerAssembly,
+            string ownerType,
+            List<string> placeholders)
+        {
+            var children = new List<BaseInstanceState>();
+            nodeState.GetChildren(context, children);
+
+            foreach (BaseInstanceState child in children)
+            {
+                string browseName = child.BrowseName?.Name ?? string.Empty;
+                bool hasPlaceholderName =
+                    browseName.Length > 1 &&
+                    browseName[0] == '<' &&
+                    browseName[browseName.Length - 1] == '>';
+
+                bool hasPlaceholderModellingRule =
+                    child.ModellingRuleId == ObjectIds.ModellingRule_OptionalPlaceholder ||
+                    child.ModellingRuleId == ObjectIds.ModellingRule_MandatoryPlaceholder;
+
+                if (hasPlaceholderName || hasPlaceholderModellingRule)
+                {
+                    string modellingRule = child.ModellingRuleId?.ToString() ?? "<null>";
+                    placeholders.Add(
+                        $"{ownerAssembly}: {ownerType}: {child.GetDisplayPath()} (BrowseName='{browseName}', ModellingRuleId='{modellingRule}')");
+                }
+
+                CollectInstantiatedPlaceholders(
+                    context,
+                    child,
+                    ownerAssembly,
+                    ownerType,
+                    placeholders);
+            }
+        }
+
+        /// <summary>
+        /// Discover loadable public NodeState types from reachable Opc.Ua assemblies.
+        /// </summary>
+        private static IEnumerable<Type> GetOpcUaNodeStateTypes()
+        {
+            var assemblies = new Dictionary<string, Assembly>(StringComparer.OrdinalIgnoreCase);
+            var toScan = new Queue<Assembly>();
+
+            void TryEnqueueAssembly(Assembly assembly)
+            {
+                if (assembly == null || assembly.IsDynamic)
+                {
+                    return;
+                }
+
+                AssemblyName assemblyName = assembly.GetName();
+
+                if (!assemblyName.Name.StartsWith("Opc.Ua", StringComparison.Ordinal))
+                {
+                    return;
+                }
+
+                if (assemblies.ContainsKey(assembly.FullName))
+                {
+                    return;
+                }
+
+                assemblies[assembly.FullName] = assembly;
+                toScan.Enqueue(assembly);
+            }
+
+            TryEnqueueAssembly(typeof(NodeState).Assembly);
+            TryEnqueueAssembly(typeof(OrderedListState).Assembly);
+            TryEnqueueAssembly(typeof(StateTypesTests).Assembly);
+
+            foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
+            {
+                TryEnqueueAssembly(assembly);
+            }
+
+            while (toScan.Count > 0)
+            {
+                Assembly assembly = toScan.Dequeue();
+
+                foreach (AssemblyName reference in assembly.GetReferencedAssemblies())
+                {
+                    if (!reference.Name.StartsWith("Opc.Ua", StringComparison.Ordinal))
+                    {
+                        continue;
+                    }
+
+                    try
+                    {
+                        TryEnqueueAssembly(Assembly.Load(reference));
+                    }
+                    catch
+                    {
+                        // Nothing we can do if an assembly fails to load, just skip it.
+                    }
+                }
+            }
+
+            return assemblies.Values
+                .SelectMany(GetExportedTypesSafe)
+                .Where(IsNodeStateType)
+                .GroupBy(type => type.AssemblyQualifiedName)
+                .Select(group => group.First());
+        }
+
+        /// <summary>
+        /// Return exported types while tolerating partial type-load failures.
+        /// </summary>
+        private static IEnumerable<Type> GetExportedTypesSafe(Assembly assembly)
+        {
+            try
+            {
+                return assembly.GetExportedTypes();
+            }
+            catch (ReflectionTypeLoadException e)
+            {
+                // Continue with loadable public types if some types in the assembly fail to load.
+                return e.Types.Where(type => type != null && type.IsPublic);
+            }
+        }
     }
 
     /// <summary>