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I had created a wcf service and client application to communicate with the service. My project working fine when service send data to client application but getting error while sending data back to service and getting error on service side like this

An exception of type 'System.NullReferenceException' occurred in HostWCF.DLL but was not handled in user code Additional information: Object reference not set to an instance of an object.

This is the functions on client side to call and get data to or from server:-

  us = client.GetDataFromServerForTenderMaster(machine);
  cmd.Connection = con;
  SubmitDataCollection sDC = new SubmitDataCollection();
  string sqlcommand = "";
  try
  {
    foreach (HostWCF.TableNameTenderMaster item in sDC.SubmitToTableNameTenderMaster())
    {
      Console.WriteLine(client.State);
      Console.ReadLine();
      do
      {

        sub = client.SubmitDataToServerForTenderMaster(machine, item);
        if (sub == true)
        {
           if (item.DeleteStatus == true)
           {
              DeleteStatus = 1;
           }
           else
           {
                DeleteStatus = 0;
           }
           if (item.Local == true)
           {
            LocalStatus = 1;
           }
           else
           {
            LocalStatus = 0;
           }
           if (item.Global == true)
           {
             GlobalStatus = 1;
           }
           else
           {
             GlobalStatus = 0;
           }
           sqlcommand = "UPDATE [TenderMaster] SET [TenderCode] = " + item.TenderCode
           + " ,[TenderCodeNumber] = '" + item.TenderCodeNumber + "' ,[TenderName] =  
           '" + item.TenderName + "' ,[StartingDate] = '" + item.StartingDate + "' 
           ,[EndingDate] = '" + item.EndingDate + "' ,[ClientName] = '" + 
           item.ClientName + "' ,[Address] = '" + item.Address + "' ,[ContractoreName] 
           = '" + item.ContractoreName + "' ,[WorkName] = '" + item.WorkName + "' 
          ,[WorkOrderNo] = '" + item.WorkOrderNo + "' ,[STno] = '" + item.STno + "' 
          ,[VatNo] = '" + item.VatNo + "' ,[Estimatetime] = '" + item.Estimatetime  
          +"' 
          ,[EstimateAmount] = '" + item.EstimateAmount + "' ,[UserId] = '" + 
          item.UserId + "' ,[Datetime] = '" + item.Datetime + "' ,[Status] = " + 
          item.Status + " ,[LocationID] = '" + item.LocationID + "' ,[Sync_Status] = " 
          + syncStatus  + "  ,[Sync_Datetime] = '" + item.Sync_Datetime + "' ,[Layer] 
          = '" + item.Layer + "',[Dt] = '" + item.Dt + "' ,[Location] = '" + 
          item.Location + "'  ,[Local] = " + LocalStatus + " ,[Global] = " + 
          GlobalStatus + " ,[DeleteStatus] = " + DeleteStatus + " WHERE [TenderCode] = 
          " + item.TenderCode + " and  [LocationID] = '" + item.LocationID + "' and 
          [Layer] ='" + item.Layer + "'";

          cmd.CommandText = sqlcommand;
          con.Open();
          cmd.ExecuteNonQuery();
          con.Close();
          }
        } while (sub == false);

and my functions are like this on server side :-

public bool GetDataFromServerForTenderMaster(string MachineID)

to send data to client application this works fine.

public bool SubmitDataToServerForTenderMaster(string MachineID,TableNameTenderMaster tn)

while sending data from client application it give error in this area as below.

 [DataContract]
    public class TableNameTenderMaster
    {
        private int _TenderCode;
        private string _TenderCodeNumber;
        private string _TenderName;
        private string _StartingDate;
        private string _EndingDate;
        private string _ClientName;
        private string _Address;
        private string _ContractoreName;
        private string _WorkName;
        private string _WorkOrderNo;
        private string _STno;
        private string _VatNo;
        private string _Estimatetime;
        private string _EstimateAmount;
        private string _UserId;
        private DateTime _Datetime;
        private int _Status;
        private string _LocationID;
        private bool _Sync_Status;
        private DateTime _Sync_Datetime;
        private string _Layer;
        private string _Dt;
        private string _Location;
        private bool _Local;
        private bool _Global;
        private bool _DeleteStatus;
        private bool _UpdateStatus;

        [DataMember]
        public int TenderCode
        {
            get
            {
                return _TenderCode;
            }
            set
            {
                if (value == null)
                {
                    value = 0;
                }
                _TenderCode = value;
            }
        }
        [DataMember]
        public string TenderCodeNumber
        {
            get
            {
                return _TenderCodeNumber;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _TenderCodeNumber = value.Trim();
            }
        }
        [DataMember]
        public string TenderName
        {
            get
            {
                return _TenderName;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _TenderName = value.Trim();
            }
        }
        [DataMember]
        public string StartingDate
        {
            get
            {
                return _StartingDate;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _StartingDate = value.Trim();
            }
        }
        [DataMember]
        public string EndingDate
        {
            get
            {
                return _EndingDate;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _EndingDate = value.Trim();
            }
        }
        [DataMember]
        public string ClientName
        {
            get
            {
                return _ClientName;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _ClientName = value.Trim();
            }
        }
        [DataMember]
        public string Address
        {
            get
            {
                return _Address;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _Address = value.Trim();
            }
        }
        [DataMember]
        public string ContractoreName
        {
            get
            {
                return _ContractoreName;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _ContractoreName = value.Trim();
            }
        }
        [DataMember]
        public string WorkName
        {
            get
            {
                return _WorkName;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _WorkName = value.Trim();
            }
        }
        [DataMember]
        public string WorkOrderNo
        {
            get
            {
                return _WorkOrderNo;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _WorkOrderNo = value.Trim();
            }
        }
        [DataMember]
        public string STno
        {
            get
            {
                return _STno;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _STno = value.Trim();
            }
        }
        [DataMember]
        public string VatNo
        {
            get
            {
                return _VatNo;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _VatNo = value.Trim();
            }
        }
        [DataMember]
        public string Estimatetime
        {
            get
            {
                return _Estimatetime;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _Estimatetime = value.Trim();
            }
        }
        [DataMember]
        public string EstimateAmount
        {
            get
            {
                return _EstimateAmount;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _EstimateAmount = value.Trim();
            }
        }
        [DataMember]
        public string UserId
        {
            get
            {
                return _UserId;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _UserId = value.Trim();
            }
        }
        [DataMember]
        public DateTime Datetime
        {
            get
            {
                return _Datetime;
            }
            set
            {
                _Datetime = value;
            }
        }
        [DataMember]
        public int Status
        {
            get
            {
                return _Status;
            }
            set
            {
                if (value == null)
                {
                    value = 0;
                }
                _Status = value;
            }
        }
        [DataMember]
        public string LocationID
        {
            get
            {
                return _LocationID;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _LocationID = value.Trim();
            }
        }
        [DataMember]
        public bool Sync_Status
        {
            get
            {
                return _Sync_Status;
            }
            set
            {
                _Sync_Status = value;
            }
        }
        [DataMember]
        public DateTime Sync_Datetime
        {
            get
            {
                return _Sync_Datetime;
            }
            set
            {
                _Sync_Datetime = value;
            }
        }
        [DataMember]
        public string Layer
        {

            get
            {
                return _Layer;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _Layer = value.Trim();
            }
        }

        private string _SyncMachineID;
        [DataMember]
        public string SyncMachineID
        {
            get
            {
                return _SyncMachineID;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _SyncMachineID = value.Trim();
            }
        }

        [DataMember]
        public string Dt
        {
            get
            {
                return _Dt;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _Dt = value.Trim();
            }
        }
        [DataMember]
        public string Location
        {
            get
            {
                return _Location;
            }
            set
            {
                if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")
                {
                    value = "";
                }
                _Location = value.Trim();
            }
        }
        [DataMember]
        public bool Local
        {
            get
            {
                return _Local;
            }
            set
            {
                _Local = value;
            }
        }
        [DataMember]
        public bool Global
        {
            get
            {
                return _Global;
            }
            set
            {
                _Global = value;
            }
        }
        [DataMember]
        public bool DeleteStatus
        {
            get
            {
                return _DeleteStatus;
            }
            set
            {
                _DeleteStatus = value;
            }
        }
        public bool UpdateStatus
        {
            get
            {
                return _UpdateStatus;
            }
            set
            {
                _UpdateStatus = value;
            }
        }
    }

I had done some research but not getting the solution for this problem. please anybody know the solution for this problem.

Panagiotis Kanavos
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Akashkumar
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  • possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) – nvoigt Nov 19 '13 at 06:25
  • 4
    This is a bit vexing error since you typically don't get further details. Just put breakpoint on top of your program and step through it - Visual Studio allows you to run both programs in debug. But as I see in you code - the setters for strings. value.Trim() ... if "value" is null, you get NullReferenceException. Check "if (value == null || value.Trim() ...". Of course you _should_ check everything for null in either ifs or try-catch. – eMko Nov 19 '13 at 06:33
  • Have you debugged the code and checked each variable to see if they any are null? – rhughes Nov 19 '13 at 06:41
  • 1
    probably one of your properties gets a null value and the call `value.Trim()` fails? – Jehof Nov 19 '13 at 06:45
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    Even if value is not null, the expression `value.Trim() == null`will always return false. – Koen Nov 19 '13 at 06:46
  • Thanks Guys your knowledge help me a lot i had got the solution. I had just removed DataMember Attribute from SyncMachineID. this is the one giving me error. Once again Thank you so much – Akashkumar Nov 19 '13 at 09:31
  • your value.Trim() issue _will_ be a problem once the checks actually get triggered by a null value for `value`. You might as well leave them out altogether if you don't fix them :) – oerkelens Nov 19 '13 at 10:05
  • @Akashkumar instead of adding "solved" keyword to your title and write it within a comment, just post your solution as an answer an accept it. – Ahmet Kakıcı Dec 31 '13 at 11:35

1 Answers1

2

Try changing 

if (value.Trim() == null || value.Trim() == string.Empty || value.Trim() == "")

to 

if (string.NullOrEmpty(value))

for starters. Your original line has several problems:

  • if value is null, Trim() will throw an exception
  • you do three checks on a trimmed string, which all would yield the same result on the original string anyway
  • you do three checks, where one is enough
oerkelens
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