client.load_data_type_definitions does not create expected class for custom structure in ua module

[scotthz]

I am trying to instantiate a custom structure type following the guidance in #839 (Usage of Extension Objects). The structure (ScanSettings) is defined and browsable. But after calling load_data_type_definitions I get an error trying to instantiate the expected class. Running the following snippet prints the structure type's browse name then hits an AttributeError on ua.ScanSettings().

What am I missing here?

        root = client.get_root_node()
        scan_settings_node = await root.get_child(["0:Types", "0:DataTypes", "0:BaseDataType", "0:Structure", "3:ScanSettings"])
        print(await scan_settings_node.read_browse_name())

        await client.load_data_type_definitions()
        scan_settings = ua.ScanSettings()

Connecting to opc.tcp://192.168.37.205:4840
QualifiedName(NamespaceIndex=3, Name='ScanSettings')
...
    scan_settings = ua.ScanSettings()
                    ^^^^^^^^^^^^^^^
AttributeError: module 'asyncua.ua' has no attribute 'ScanSettings'

[schroeder-]

Maybe the server is doesn't support the new datatype description.
Try to load load_type_definitions instead of load_data_type_definitions.
If this doesn't work can you activate logging and post the output?

[scotthz]

Thank you for your quick response! Your suggestion to use load_type_definitions is working and enables me to move forward.
I do get this error message, I guess it is safe to ignore for now?

Deprecated since spec 1.04, call load_data_type_definitions

[schroeder-]

You can ignore that message, for your usecase. Because your server doesn't support the 1.04 datatype defintions.

[m-stredansky]

If you have custom data types on OPC Server, It would be nice to load them first either by creating task for that or wait for load.

task_load_types = asyncio.create_task(client.load_type_definitions())
type_definitions_loaded = await asyncio.wait_for(task_load_types, timeout=10) # Max timeout 10

Method load_type_definitions is supported only in versions <= 1.04 and is now deprecated.

For newer versions for loading custom types (structures/extension objects) definition from server use method load_data_type_definitions. I recommend either installing version 1.04 and keeping the compatibility or going to a higher version with a new call.