Null values for attributes

[SachaSaxer]

I'm trying to write a sub section of a struct (which is also a struct) so I'm reading the DataType attribute of the node of the sub-struct but for some reason I'm getting a null value which doesn't make any sense whatsoever. My code for reading the node attributes is below, I found it in one of those APIHelper classes.

`public Dictionary<uint, DataValue> ReadNodeAttributes(String nodeIdString)
{
if (null == _session)
return new Dictionary<uint, DataValue>(); //throw not connected exception

      Dictionary<int, uint> attributeDictionary = new Dictionary<int, uint>()
      {
          {1, Attributes.NodeId },
          {2, Attributes.NodeClass },
          {3, Attributes.BrowseName },
          {4, Attributes.DisplayName },
          {5, Attributes.Value },
          {6, Attributes.DataType},
          {7, Attributes.ValueRank},
          {8, Attributes.ArrayDimensions},
          {9, Attributes.AccessLevel }
      };
      //Create a nodeId using the identifier string
      NodeId nodeId = new NodeId(nodeIdString);

      //Create a read value id collection to store the nodes to read
      ReadValueIdCollection nodesToRead = new ReadValueIdCollection();

      //Create a StatusCodeCollection
      DataValueCollection dataValueCollection = new DataValueCollection();

      //Create a DiagnosticInfoCollection
      DiagnosticInfoCollection diag = new DiagnosticInfoCollection();

      //Go through the attribute dictionary and create the nodes accordingly
      for (int i = 0; i < attributeDictionary.Count; i++)
      {
          ///Create a read value id with the nessessary attribute
          ReadValueId nodeToRead = new ReadValueId();
          nodeToRead.NodeId = nodeId;
          nodeToRead.AttributeId = attributeDictionary[i + 1];
          nodesToRead.Add(nodeToRead);
      }
      //Read the read value id collection
      _session.Read(null, 0, TimestampsToReturn.Neither, nodesToRead, out dataValueCollection, out diag);
      //Create a dictionary to store the attribute values
      Dictionary<uint, DataValue> attributeValues = new Dictionary<uint, DataValue>();
      //Go through the data value collection to store every data value according to its attribute identifier
      int counter = 1;
      foreach (DataValue dataValue in dataValueCollection)
      {
          attributeValues.Add(attributeDictionary[counter], dataValue);
          counter += 1;
      }
      return attributeValues;
  }

`

Any ideas where I'm doing something wrong?

[mregen]

why don't you use a helper function like:

public async Task<(IList<Node>, IList<ServiceResult>)> ReadNodesAsync(
    IList<NodeId> nodeIds,
    NodeClass nodeClass,
    bool optionalAttributes = false,
    CancellationToken ct = default);

It deals with all the attributes, if you set NodeClass.Unspecified it reads all supported attributes. You may have to cast the result to e.g. VariableNode.