Error while passing the DataContract object from client to Server ......

Question

Defined COntracts:

==========================================================================

[ServiceContract]
    public interface IService1
    {
        [OperationContract]
        bool Create(String tableName);
        [OperationContract]
        bool Insert(DataModel row);
        [OperationContract]
        bool Delete(DataModel row);
        [OperationContract]
        bool Update(DataModel row);




    }
    [DataContract ]
    [DataServiceKey ("PartitionKey","RowKey")]
    public class DataModel// : TableServiceEntity
    {
       // TableServiceEntity Ent = new TableServiceEntity();
        [DataMember]
        public String DN{get;set;}
        [DataMember]
        public String Data{get;set;}
        [DataMember]
        public String PartitionKey { get; set; }
        [DataMember]
        public String RowKey { get; set; }
    }

=============================================================================

SERVER SERVICE:  

public class TableService : IService1
    {
        public String tableName;
        public TableServiceContext context;
        public bool Create(String tableName)
        {
            this.tableName = tableName;
            string accountname = "devstoreaccount1";
            string accountkey = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==";
            string tableServiceAddress = "http://127.0.0.1:10002/devstoreaccount1";
            var credentials = new StorageCredentialsAccountAndKey(accountname, accountkey);
            var account = new CloudStorageAccount(credentials, false);
            var tableAcc = new CloudTableClient(tableServiceAddress, credentials);
            context = new TableServiceContext(tableServiceAddress, credentials);
            return tableAcc.CreateTableIfNotExist(tableName);
        }


        public bool Insert(DataModel row)
        {
            context.AddObject(tableName, row);// I am getting error here as row object is empty ie NullValueReference
            context.SaveChangesWithRetries();
            return true;
        }
.........//other func

}

==============================================================================

CLIENT CODE: (WEB App with form interface) 

    public partial class _Default : System.Web.UI.Page
    {
        Service1Client s;
        protected void Page_Load(object sender, EventArgs e)
        {
            s= new Service1Client();
        }


        protected void Button1_Click(object sender, EventArgs e)
        {
            bool handle=s.Create(tableName.Text.ToString());
            response.Text = handle.ToString();
        }


        protected void Button2_Click(object sender, EventArgs e)
        {
            DataModel row = new DataModel();
            row.PartitionKey = pKey.Text.ToString();
            row.RowKey = rKey.Text.ToString();
            row.DN = dn.Text.ToString();
            row.Data = data.Text.ToString();
            //response.Text = row.ToString();
           bool handle=s.Insert(row);
           // response.Text = handle.ToString();
        }
    }

========================================================

---

A.Navarajan

Answer 1

 I am getting the error in server side while calling the Insert function....it says row ie object of Datamodel is empty ... it asking me to use new... I dont know why i am getting the error...

   In the client side i am storing all the value in the Datamodel object and passing it to server...And the server is says its empy...

  I think there is some error while serializing... But i dont get it...Somebody help me...

---

A.Navarajan

Answer 2

Hi Navarajan,

This seems to be a WCF issue. I think at the moment you call the Insert method the TableServiceContext is null. The WCF instance mode is per call (http://msdn.microsoft.com/en-us/magazine/cc163590.aspx). This means, each time you call the service a new instance of that class is created server side. Meaning, when you call the Insert method, it's as if you never executed the Create method (for that request). What I advise you to do is to call the Create method in your Insert method and this should solve your issue.

Sandrino

Answer 3

Yes Sandrino,

               You are absolutely right...It solved the problem...thanks for your immediate reply... 

---

A.Navarajan