Find the coordinates returned by the server after send commands GPS Tracker (TK303 etc)

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• C# - Adding condition to func results in stack overflow exception

  I have a func as part of specification class which sorts the given iqueryable

  Func<IQueryable<T>, IOrderedQueryable<T>>? Sort { get; set; }
  

  When i add more than one condition to the func like below , it results in stack overflow exception.

  spec.OrderBy(sc => sc.Case.EndTime).OrderBy(sc => sc.Case.StartTime);
  

  The OrderBy method is implemented like this

  public ISpecification<T> OrderBy<TProperty>(Expression<Func<T, TProperty>> property)
      {
          _ = Sort == null ? Sort = items => items.OrderBy(property) : Sort = items => Sort(items).ThenBy(property);
          return this;
      }
  

  Chaining or using separate lines doesn't make a difference.

  This problem gets resolved if I assign a new instance of the specification and set it's func, but i don't want to be assigning to a new instance everytime. Please suggest what am i missing here and how to reuse the same instance (if possible).
• How to projection fields for a dictionary (C#, MongdoDB)

  I am trying my luck here, I have a model which is like the following

  public class RowData : BaseBsonDefinition
  {
  .
    [BsonExtraElements]
    [BsonDictionaryOptions(DictionaryRepresentation.ArrayOfDocuments)]
    public Dictionary<string, object> Rows { get; set; } = new(StringComparer.OrdinalIgnoreCase);
  .
  }
  
  

  In result, the schema in the MongoDB looks like

  {
  "_id": {
      "$binary": {
        "base64": "HiuI1sgyT0OZmcgGUit2dw==",
        "subType": "03"
      }
    },
    "c1": "AAA",
    "c8": "Fully Vac",
    "c10": "",
  }
  

  Those c1, c8 and c10 fields are keys from the dictionary, my question is how to dynamic project those fields?

  I tried

  Builders<RowData>.Projection.Exclude(p => "c1")
  

  It seems the MongoDB driver can not handle a value directly.

  Anyone could point me in the correct direction?

  Thanks,
• How do I add new DataSource to an already Databinded CheckBoxList

  i'm building a web form that show Database's item(Tables, Rows, FK,...)

  I have a CheckBoxList of Tables (chkListTable) which will show a new CheckBoxList of Rows (chkListRow) everytime I SelectedIndexChanged from chkListTable. The problem is i can show the items from chkListTable with 1 selected item. But i don't know how to show chkListRow if multiple item from chkListTable are selected.

  Here are my codes:

  aspx:

  <div>
               <asp:Label ID="Label2" runat="server" Text="Table: "></asp:Label>
               <asp:CheckBoxList ID="chkListTable" runat="server"
                   DataTextField="name"
                   DataValueFeild="name"
                   AutoPostBack="true"
                   OnSelectedIndexChanged="chkListTable_SelectedIndexChanged">
               </asp:CheckBoxList>
          </div>
          <div>
               <asp:CheckBoxList ID="chkListRow" runat="server"
               DataTextField="COLUMN_NAME"
               DataValueField="COLUMN_NAME"
               RepeatDirection="Horizontal">
               </asp:CheckBoxList>
          </div>
  

  aspx.cs:

  protected void chkListTable_SelectedIndexChanged(object sender, EventArgs e)
      {
          tableName.Clear();
          
          foreach (ListItem item in chkListTable.Items)
          {
              if(item.Selected)
              {
                  tableName.Add(item.Text.Trim());
              }    
          }
  
          for(int i = 0; i < tableName.Count; i++)
          {
              String query = "USE " + dbname +
                  " SELECT * FROM information_schema.columns" +
                  " WHERE table_name = '" + tableName[i] + "'" +
                  " AND COLUMN_NAME != 'rowguid'";
              chkListRow.DataSource = Program.ExecSqlDataReader(query);
              chkListRow.DataBind(); 
              Program.conn.Close();
          }
      }
  

  Program.cs:

  public static bool Connect()
      {
          if (Program.conn != null && Program.conn.State == ConnectionState.Open)
              Program.conn.Close();
          try
          {
              Program.conn.ConnectionString = Program.constr;
  
              Program.conn.Open();
  
              return true;
          }
  
          catch (Exception e)
          {
              return false;
          }
      }
  
      public static SqlDataReader ExecSqlDataReader(String query)
      {
          SqlDataReader myreader;
          SqlCommand sqlcmd = new SqlCommand(query, Program.conn);
          sqlcmd.CommandType = CommandType.Text;
          if (Program.conn.State == ConnectionState.Closed) Program.conn.Open();
          try
          {
              myreader = sqlcmd.ExecuteReader();
              return myreader;
              myreader.Close();
          }
          catch (SqlException ex)
          {
              Program.conn.Close();
              return null;
          }
      }
  

  I want my display to be like this:

  [x]Table1 [x]Table2 [ ]Table3
  [ ]Row1(Table1) [ ]Row2(Table1) [ ]Row3(Table1)
  [ ]Row1(Table2) [ ]Row2(Table2)
  
• Socket.IO cannot establish a connection

  I use socket.io-client for Javascript server on JAVA and when I enter address 'ws://10.201.223.67:9902/' the request is not by 'ws' but by 'http'.

  It returns

  Although I understand it should just come back 0

  It keeps trying to connect.To connect using my own written hook

  export function useSocketIO(url: string) {
  const ioRef = useRef<Socket>();
  const [connected, setConnected] = useState(false);
  
  useEffect(() => {
  ioRef.current = io(url, {
    transportOptions: {
      polling: {
        extraHeaders: {
          Authorization: `Bearer ${APIAuth.accessToken}`,
        },
      },
    },
  });
  ioRef.current.on('connect', () => {
    console.log('WS Connected to', url);
    setConnected(() => true);
  });
  
  ioRef.current.on('disconnect', () => {
    console.log('WS disconnected');
    setConnected(() => false);
  });
  
  return () => {
    console.log('WS destroyed');
    ioRef.current?.close();
  };
  }, [url]);
  
  return {
  io: ioRef.current,
  connected,
   };
   }
  
• Steps involved in making a TCP connection

  I am 18 and about to go to college for CS, I know nothing about socket programming in C.

  I read the man pages on sockets, can you tell me if I got the steps right?

  Server Steps:

  • create a socket with socket()

  • create an address with a struct [presumably using some kind of sockaddr struct variant]

  • bind the socket to the address with bind()

  • listen for a connection with listen()

  • accept the connection, and move the connection to another socket using accept() to free up the original "listening" socket

  • use read() and write() to communicate over the new socket

  Client Steps:

  • create a socket with socket()

  • specify the address of the server we want to connect to [presumably using some sockaddr struct variant]

  • connect the socket to the address using connect()

  • use read() and write() to communicate over the socket
• Websocket with special characters

  I am using websocket with client nodejs and server golang (net library) via tcp. I am read data sent from client but many special chars. Some one can help me about that?

  Data received:

  \u0016\u0003\u0001\u0002\u0000\u0001\u0000\u0001\ufffd\u0003\u0003x\ufffd_\ufffdj\ufffd\ufffd\ufffd\ufffdȬ{\ufffd \ufffdI\u003c9\u000bC1YŲ\ufffdVp\u0017\ufffd\u000e`\ufffd \ufffd\ufffd\ufffd\u0017\ufffd\ufffd=\\u0002\ufffd~,\u0011\ufffdn\ufffd\ufffdY\u0010\ufffd\u001c\ufffdw\u000f\ufffd\ufffd(hfK\ufffd\ufffd\u0000 \u001a\u001a\u0013\u0001\u0013\u0002\u0013\u0003\ufffd+\ufffd/\ufffd,\ufffd0̨̩\ufffd\u0013\ufffd\u0014\u0000\ufffd\u0000\ufffd\u0000/\u00005\u0001\u0000\u0001\ufffd\ufffd\ufffd\u0000\u0000\u0000\u0000\u0000\u0014\u0000\u0012\u0000\u0000\u000fvenus.localhost\u0000\u0017\u0000\u0000\ufffd\u0001\u0000\u0001\u0000\u0000"

  This func use to accept tcp

  func (s *WebsocketServer) Serve() {
      if s.running {
          return
      }
      s.running = true
  
      for _, lsn := range s.lsnList {
          for i := 0; i < s.accepts; i++ {
              go func(lsn2 *net.TCPListener) {
                  var (
                      conn *net.TCPConn
                      err  error
                  )
                  for {
                      if conn, err = AcceptTCP(lsn2); err != nil {
                          // if listener close then return
                          log.Error("listener.Accept(\"%s\") error(%v)", lsn2.Addr().String(), err)
                          return
                      }
                      if err = conn.SetKeepAlive(s.c.Keepalive); err != nil {
                          log.Error("conn.SetKeepAlive() error(%v)", err)
                          return
                      }
                      if err = conn.SetReadBuffer(s.c.ReceiveBuf); err != nil {
                          log.Error("conn.SetReadBuffer() error(%v)", err)
                          return
                      }
                      if err = conn.SetWriteBuffer(s.c.SendBuf); err != nil {
                          log.Error("conn.SetWriteBuffer() error(%v)", err)
                          return
                      }
  
                      go s.establishWebsocketConnection(conn)
                  }
              }(lsn)
          }
      }
  }
  
  func (s *WebsocketServer) establishWebsocketConnection(conn net.Conn) {
      var (
          // conn2         = NewBufferedConnSize(conn, 66560)
          req           *websocket.Request
          websocketConn *websocket.Conn
          err           error
      )
  
      rr := bufio.NewReader(conn)
      if req, err = websocket.ReadRequest(rr); err != nil || req.RequestURI != "/apiws" {
          conn.Close()
          if err != io.EOF {
              log.Errorf("websocket.ReadRequest(rr) error(%v)", err)
          }
          return
      } else {
          wr := bufio.NewWriter(conn)
          websocketConn, err = websocket.Upgrade(conn, rr, wr, req)
          if err != nil {
              log.Errorf("websocket.Upgrade(rr) error(%v)", err)
              conn.Close()
              return
          }
      }
  
      codec, err := NewCodecByName(s.c.ProtoName, websocketConn)
      tcpConn := NewTcpConnection2(s.c.ServerName, websocketConn, s.c.SendChanSize, codec, true, s)
  
      // log.Info("establishTcpConnection...")
      defer func() {
          if err := recover(); err != nil {
              log.Error("tcp_server handle panic: %v\n%s", err, debug.Stack())
              tcpConn.Close()
          }
      }()
  
      s.onNewConnection(tcpConn)
  
      for {
          tcpConn.conn.SetReadDeadline(time.Now().Add(time.Minute * 6))
          msg, err := tcpConn.Receive()
          if err != nil {
              log.Error("conn: %s recv error: %v", tcpConn, err)
              return
          }
  
          if msg == nil {
              log.Error("recv a nil msg by conn: %s", tcpConn)
              continue
          }
  
          if s.callback != nil {
              // log.Info("onConnectionDataArrived - conn: %s", conn)
              if err := s.callback.OnConnectionDataArrived(tcpConn, msg); err != nil {
              }
          }
      }
  }
  

  Function from websocket file, I print data here like above

  func ReadRequest(r *bufio.Reader) (req *Request, err error) {
      var (
          b  []byte
          ok bool
      )
      req = &Request{reader: r}
      if b, err = req.readLine(); err != nil {
          return
      }
      log.Errorf("websocket.ReadRequest: %s", string(b))
  
      if req.Method, req.RequestURI, req.Proto, ok = parseRequestLine(string(b)); !ok {
          return nil, fmt.Errorf("malformed HTTP request %s", b)
      }
      if req.Header, err = req.readMIMEHeader(); err != nil {
          return
      }
      req.Host = req.Header.Get("Host")
      return req, nil
  }
  
  func (r *Request) readLine() ([]byte, error) {
      var line []byte
      for {
          l, more, err := r.reader.ReadLine()
          if err != nil {
              return nil, err
          }
          // Avoid the copy if the first call produced a full line.
          if line == nil && !more {
              return l, nil
          }
          line = append(line, l...)
          if !more {
              break
          }
      }
      return line, nil
  }
  

  Please help me
• Find GPS coordinates of new location with respect to another GPS location at a range, azimuth and elevation & roll, pitch and yaw

  I have GPS coordinates of my quadcopter A - LatA, LongA and HeightA.

  My quadcopter attitude is not straight and level, it has current Roll angle - RollA, current Pitch angle - PitchA and Current Heading HdgA with respect to North.

  My quadcopter focusses/throws a light at a range R meters, elevation E degrees (with respect to horizontal plane of quadcopter), Azimuth A (with respect to nose/longitudinal axes of quadcopter).

  I need to find the GPS coordinates of location where my quadcopter focusses its light.
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  I have a Novatel OEM3 card which can't handle the GPS week rollover, it gives 2002 as the current year.

  As the OEM3 protocol is supported by RTKLIB, is there a workaround or patch for RTKLIB? So that I can still use this card?
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