Is there a typeUtility for the DataType conversions during write opertations

[ravi-kothapally]

During write operations, I am reading values as objects, so I need to convert them to Milo data types. However, there seem to be many such types. Is there a utility that can help with this?
Any guidance on this would be greatly appreciated!
am tying to do something like this, but is it enough??

    private static Class<?> getBackingClassForDataType(NodeId dataTypeNodeId) {
        for (BuiltinDataType dataType : BuiltinDataType.values()) {
            if (dataType.getNodeId().equals(dataTypeNodeId)) {
                return dataType.getBackingClass();
            }
        }
        if (Identifiers.Integer.equals(dataTypeNodeId)) {
            return Integer.class;
        }
        if (Identifiers.UInteger.equals(dataTypeNodeId)) {
            return UInteger.class;
        }
        if (Identifiers.Number.equals(dataTypeNodeId)) {
            return Number.class;
        }
        if (Identifiers.Enumeration.equals(dataTypeNodeId)) {
            return Enumeration.class;
        }
        return null;
    }

[kevinherron]

Yes, DataTypeTree is what you want.

NodeId dataTypeId = ...;
    
DataTypeTree dataTypeTree = client.getDataTypeTree();

OpcUaDataType dataType = dataTypeTree.getBuiltinType(dataTypeId);
Class<?> backingClass = dataTypeTree.getBackingClass(dataTypeId);

[kevinherron]

If you aren't using dev/1.0, this exists in the 0.6.x line as well: https://github.com/eclipse-milo/milo/blob/master/opc-ua-sdk/sdk-core/src/main/java/org/eclipse/milo/opcua/sdk/core/DataTypeTree.java

[ravi-kothapally]

Thank you @kevinherron I was able to move forward , but for a generic OPC UA client, I am decoding a custom structured data type from an ExtensionObject using JsonBsdParser. Here’s an example of the decoded value:
{ "nodeId": "ns=2;s=HelloWorld/CustomUnionTypeVariable", "value": { "SwitchField": 2.0, "bar": "hello" }}
Now, I want to modify this value and write it back to the OPC UA server.
How can I properly construct an ExtensionObject from the modified struct so that it can be written back?
Would appreciate any guidance. Thanks!

[kevinherron]

You just call ExtensionObject.encode like the examples do:

milo/milo-examples/client-examples/src/main/java/org/eclipse/milo/examples/client/ReadWriteCustomDataTypeNodeExample.java

Lines 73 to 78 in c6a875c

	ExtensionObject modifiedXo = ExtensionObject.encode(
	client.getStaticSerializationContext(),
	modified,
	xo.getEncodingId(),
	OpcUaDefaultBinaryEncoding.getInstance()
	);

The difference is that the object you pass will be a JsonObject (I think?) instead, and you'll use client.getDynamicSerializationContext().

[kevinherron]

You might want to start thinking about developing against dev/1.0. The BSD parser stuff is deprecated, and the JSON representation is a little different (more complete).

See https://github.com/eclipse-milo/milo/blob/dev/1.0/milo-examples/client-examples/src/main/java/org/eclipse/milo/examples/client/UnifiedAutomationReadCustomDataTypeExample2.java

[ravi-kothapally]

Thank you, @kevinherron! am using 0.6.15 and Converting the incoming Map to a JsonObject worked.