Add write support with automatic type coercion to OpcUaMonitoredNode

writeValue() Q_INVOKABLE coerces QML JS types to the exact C++ type
expected by the OPC UA node (auto-detected from DataType attribute via
opcUaDataTypeToQOpcUaType). Handles all scalar types, booleans, and
comma-separated array input. Adds writable property derived from
AccessLevel bits. Demo shows inline TextField + Write button for
writable nodes, "(READ-ONLY)" for others.

1 files changed, 42 insertions, 5 deletions

diff --git a/demo/NodePage.qml b/demo/NodePage.qml
index 1468817..442a6fd 100644
--- a/demo/NodePage.qml
+++ b/demo/NodePage.qml
@@ -91,21 +91,28 @@ Page {
         // Column headers
         RowLayout {
             Layout.fillWidth: true
-            spacing: 0
+            Layout.leftMargin: 12
+            Layout.rightMargin: 12
+            spacing: 12
             Label {
                 text: "Identifier"
                 font.bold: true
-                Layout.preferredWidth: 200
-                leftPadding: 12
+                Layout.preferredWidth: 160
             }
             Label {
                 text: "Value"
                 font.bold: true
+                Layout.preferredWidth: 160
+            }
+            Label {
+                text: "Write"
+                font.bold: true
                 Layout.fillWidth: true
             }
         }
 
         Rectangle {
+            id: separator
             Layout.fillWidth: true
             height: 1
             color: "#ccc"
@@ -128,6 +135,10 @@ Page {
                     id: node
                     nodeId: delegate.modelData
                     monitored: nodePage.StackView.status === StackView.Active
+                    onWriteCompleted: (success, message) => {
+                        var short_id = node.nodeId.substring(node.nodeId.indexOf(";s=") + 3);
+                        nodePage.logFunction(short_id + ": " + message);
+                    }
                 }
 
                 background: Rectangle {
@@ -137,19 +148,45 @@ Page {
 
                 contentItem: RowLayout {
                     spacing: 12
+
+                    // Column 1: Identifier
                     Label {
                         text: {
                             var idx = node.nodeId.indexOf(";s=");
                             return idx >= 0 ? node.nodeId.substring(idx + 3) : node.nodeId;
                         }
-                        Layout.preferredWidth: 188
+                        Layout.preferredWidth: 160
                         elide: Text.ElideRight
                     }
+
+                    // Column 2: Live value (always visible)
                     Label {
                         text: node.value !== undefined && String(node.value) !== "" ? String(node.value) : "—"
-                        Layout.fillWidth: true
+                        Layout.preferredWidth: 160
                         elide: Text.ElideRight
                     }
+
+                    // Column 3: Edit area (writable) or READ-ONLY label
+                    TextField {
+                        id: editField
+                        visible: node.writable
+                        Layout.fillWidth: true
+                        placeholderText: "Enter value..."
+                        onAccepted: node.writeValue(text)
+                    }
+                    Button {
+                        id: writeButton
+                        visible: node.writable
+                        text: "Write"
+                        onClicked: node.writeValue(editField.text)
+                    }
+                    Label {
+                        visible: !node.writable
+                        text: "(READ-ONLY)"
+                        color: "gray"
+                        font.italic: true
+                        Layout.fillWidth: true
+                    }
                 }
 
                 ToolTip.visible: hovered