How to get data from a new_struct datatype received in a @uamethod

[shineworld]

Hi all,
I'm writing an OPC UA Server using latest version 1.1.5.

The server define a new structure using the:
from asyncua.common.structures104 import new_struct, new_enum, new_struct_field

method to create and add new structure type to OPC UA Server

        async def define_work_order_datatype(server):
            res, * = await new_struct(
                server,
                idx,
                "WorkOrderDataType",
                [
                    new_struct_field("order_locked"             , ua.VariantType.Boolean),
                    new_struct_field("order_priority"           , ua.VariantType.Byte),
                    new_struct_field("job_order_code"           , ua.VariantType.String),
                    new_struct_field("customer_code"            , ua.VariantType.String),
                    new_struct_field("item_code"                , ua.VariantType.String),
                    new_struct_field("material_code"            , ua.VariantType.String),
                    new_struct_field("order_notes"              , ua.VariantType.String),
                    new_struct_field("used_deadline_datetime"   , ua.VariantType.Boolean),
                    new_struct_field("deadline_datetime"        , ua.VariantType.DateTime),
                    new_struct_field("file_name_1"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_1"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_1"       , ua.VariantType.Int32),
                    new_struct_field("file_name_2"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_2"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_2"       , ua.VariantType.Int32),
                    new_struct_field("file_name_3"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_3"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_3"       , ua.VariantType.Int32),
                    new_struct_field("file_name_4"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_4"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_4"       , ua.VariantType.Int32),
                    new_struct_field("file_name_5"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_5"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_5"       , ua.VariantType.Int32),
                    new_struct_field("file_name_6"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_6"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_6"       , ua.VariantType.Int32),
                    new_struct_field("file_name_7"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_7"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_7"       , ua.VariantType.Int32),
                    new_struct_field("file_name_8"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_8"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_8"       , ua.VariantType.Int32),
                ],
            )
            return res

Create new structure data type and method which use it as argument

           # create new structure datatype and add it to OPC UA Struct node
           work_order_datatype = await define_work_order_datatype(self.server)
 
            # create and add uamethod witch use new structure datatype as argument
            a_work_order_order_code = ua.Argument()
            a_work_order_order_code.Name = "order_code"
            a_work_order_order_code.DataType = ua.NodeId(ua.ObjectIds.String)
            a_work_order_order_code.ValueRank = -1
            a_work_order_order_code.Description = ua.LocalizedText("work order: order code")
            a_work_order_data = ua.Argument()
            a_work_order_data.Name = "data"
            a_work_order_data.DataType = work_order_datatype.nodeid
            a_work_order_data.ValueRank = -1
            a_work_order_data.Description = ua.LocalizedText("work order: data")
            await self.server.nodes.objects.add_method(
                idx,
                "work_order_add",
                self.api_work_order_add,
                [a_work_order_order_code, a_work_order_data],
                [ua.VariantType.Boolean]
            )

uamethod implementation

    @uamethod
    async def api_work_order_add(self, parent, order_code: str, data):
        # ??? HOW TO GET STRUCTURE DATA ??? 
        return True

The data content is:

[Dbg]>>> data
ExtensionObject(TypeId=NodeId(Identifier=2, NamespaceIndex=2, NodeIdType=<NodeIdType.FourByte: 1>), Body=b'\x00\x00\x05\x00\x00\x0012341\x04\x00\x00\x001234\x01\x00\x00\x003\x05\x00\x00\x00sderg\x07\x00\x00\x00dfgsdfg\x00\x00@m%\xebS\xbf\x01\x08\x00\x00\x00sdfgsdfg\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00')

I was able, in some way, to get data using struct but the code is terrible and complex to maintain:

import struct
from asyncua.ua import ua

@uamethod
async def api_work_order_add(self, parent, order_code: str, data):
    try:
        # Stampa informazioni di debug
        print("ExtensionObject TypeId:", data.TypeId)
        print("Body hex:", data.Body.hex())
        print("Body length:", len(data.Body))

        # Punto di partenza per la lettura
        offset = 0

        # Funzione di supporto per leggere stringhe
        def read_string(body, start):
            # Legge la lunghezza della stringa (4 byte)
            str_len = struct.unpack('<i', body[start:start+4])[0]
            start += 4
            
            # Se la lunghezza è -1, è una stringa vuota
            if str_len == -1:
                return '', start
            
            # Legge la stringa
            string_value = body[start:start+str_len].decode('utf-8')
            return string_value, start + str_len

        # Lettura campi booleani e byte
        order_locked = data.Body[offset] == 1
        offset += 1
        
        order_priority = data.Body[offset]
        offset += 1

        # Lettura stringhe
        job_order_code, offset = read_string(data.Body, offset)
        customer_code, offset = read_string(data.Body, offset)
        item_code, offset = read_string(data.Body, offset)
        material_code, offset = read_string(data.Body, offset)
        order_notes, offset = read_string(data.Body, offset)

        # Lettura booleano deadline
        used_deadline_datetime = data.Body[offset] == 1
        offset += 1

        # Lettura datetime (64-bit intero che rappresenta i tick di Windows)
        deadline_datetime_raw = struct.unpack('<Q', data.Body[offset:offset+8])[0]
        # Converti i tick di Windows in datetime di Python se necessario
        deadline_datetime = ua.datetime_from_win_filetime(deadline_datetime_raw) if deadline_datetime_raw != 0 else None
        offset += 8

        # Lettura dettagli file
        file_details = []
        for _ in range(8):
            file_name, offset = read_string(data.Body, offset)
            pieces_per_file = struct.unpack('<i', data.Body[offset:offset+4])[0]
            offset += 4
            requested_pieces = struct.unpack('<i', data.Body[offset:offset+4])[0]
            offset += 4
            
            file_details.append({
                'file_name': file_name,
                'pieces_per_file': pieces_per_file,
                'requested_pieces': requested_pieces
            })

        # Stampa i dati decodificati
        print("Order Locked:", order_locked)
        print("Order Priority:", order_priority)
        print("Job Order Code:", job_order_code)
        print("Customer Code:", customer_code)
        print("Item Code:", item_code)
        print("Material Code:", material_code)
        print("Order Notes:", order_notes)
        print("Used Deadline:", used_deadline_datetime)
        print("Deadline Datetime:", deadline_datetime)
        
        # Stampa dettagli dei file
        for i, file_info in enumerate(file_details, 1):
            if file_info['file_name']:
                print(f"File {i}:")
                print(f"  Name: {file_info['file_name']}")
                print(f"  Pieces per File: {file_info['pieces_per_file']}")
                print(f"  Requested Pieces: {file_info['requested_pieces']}")
        
        return True
    except Exception as e:
        print(f"Errore nella decodifica dei dati: {e}")
        import traceback
        traceback.print_exc()
        return False

There is some better and ready to use way to get info from "data" using library functions ?

[shineworld]

After a full day of try and suggestion by ChatCPT and ClaudAI (without resoults), for totally case of life I've found the solution.
This can be useful to other so I place here.

When I create the new_struct based data type in the method argument I get always a data of basic type with raw data.
But if in new_struct type I call await load_custom_struct(new_data_type) the method argument become an auto-generated class with all published data:

        async def define_work_order_datatype():
            res, _ = await new_struct(
                self.server,
                idx,
                "WorkOrderDataType",
                [
                    new_struct_field("order_locked"             , ua.VariantType.Boolean),
                    new_struct_field("order_priority"           , ua.VariantType.Byte),
                    new_struct_field("job_order_code"           , ua.VariantType.String),
                    new_struct_field("customer_code"            , ua.VariantType.String),
                    new_struct_field("item_code"                , ua.VariantType.String),
                    new_struct_field("material_code"            , ua.VariantType.String),
                    new_struct_field("order_notes"              , ua.VariantType.String),
                    new_struct_field("used_deadline_datetime"   , ua.VariantType.Boolean),
                    new_struct_field("deadline_datetime"        , ua.VariantType.DateTime),
                    new_struct_field("file_name_1"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_1"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_1"       , ua.VariantType.Int32),
                    new_struct_field("file_name_2"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_2"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_2"       , ua.VariantType.Int32),
                    new_struct_field("file_name_3"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_3"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_3"       , ua.VariantType.Int32),
                    new_struct_field("file_name_4"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_4"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_4"       , ua.VariantType.Int32),
                    new_struct_field("file_name_5"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_5"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_5"       , ua.VariantType.Int32),
                    new_struct_field("file_name_6"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_6"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_6"       , ua.VariantType.Int32),
                    new_struct_field("file_name_7"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_7"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_7"       , ua.VariantType.Int32),
                    new_struct_field("file_name_8"              , ua.VariantType.String),
                    new_struct_field("pieces_per_file_8"        , ua.VariantType.Int32),
                    new_struct_field("requested_pieces_8"       , ua.VariantType.Int32),
                ],
            )

            # TAKE CARE
            # =========
            # This call is FUNDAMENTAL for methods that use this data type to get an autogenerated WorkOrderTypeData
            # class from the server as an argument instead of receiving a generic class with the data as a stream of
            # bytes that is very difficult to interpret.
            #
            await load_custom_struct(res)
            return res

so in method I have direct data:

    @uamethod
    async def api_work_order_add(self, parent, order_code: str, data):
        try:
            print(f'order code              : {order_code}')
            print(f'order_locked            : {data.order_locked}')
            print(f'order_priority          : {data.order_priority}')
            print(f'job_order_code          : {data.job_order_code}')
            print(f'customer_code           : {data.customer_code}')
            print(f'item_code               : {data.item_code}')
            print(f'material_code           : {data.material_code}')
            print(f'order_notes             : {data.order_notes}')
            print(f'used_deadline_datetime  : {data.used_deadline_datetime}')
            print(f'deadline_datetime       : {data.deadline_datetime}')
            print(f'file_name_1             : {data.file_name_1}')
            print(f'pieces_per_file_1       : {data.pieces_per_file_1}')
            print(f'requested_pieces_1      : {data.requested_pieces_1}')
            print(f'file_name_2             : {data.file_name_2}')
            print(f'pieces_per_file_2       : {data.pieces_per_file_2}')
            print(f'requested_pieces_2      : {data.requested_pieces_2}')
            print(f'file_name_3             : {data.file_name_3}')
            print(f'pieces_per_file_3       : {data.pieces_per_file_3}')
            print(f'requested_pieces_3      : {data.requested_pieces_3}')
            print(f'file_name_4             : {data.file_name_4}')
            print(f'pieces_per_file_4       : {data.pieces_per_file_4}')
            print(f'requested_pieces_4      : {data.requested_pieces_4}')
            print(f'file_name_5             : {data.file_name_5}')
            print(f'pieces_per_file_5       : {data.pieces_per_file_5}')
            print(f'requested_pieces_5      : {data.requested_pieces_5}')
            print(f'file_name_6             : {data.file_name_6}')
            print(f'pieces_per_file_6       : {data.pieces_per_file_6}')
            print(f'requested_pieces_6      : {data.requested_pieces_6}')
            print(f'file_name_7             : {data.file_name_7}')
            print(f'pieces_per_file_7       : {data.pieces_per_file_7}')
            print(f'requested_pieces_7      : {data.requested_pieces_7}')
            print(f'file_name_8             : {data.file_name_8}')
            print(f'pieces_per_file_8       : {data.pieces_per_file_8}')
            print(f'requested_pieces_8      : {data.requested_pieces_8}')
            return True
        except
            return False

Wonderful library !!!