Object cannot be cast from DBNull to other types

Object cannot be cast from DBNull to other types.

I have a following function which throws the above error. I am handling all nulls in store procedure and in the C# code.

So where is it getting this error?

I can see the error in the catch block. But i am not understanding which line in the following create() getting the error.

public Boolean Create(DataTO DataTO)
{
    IDbTrans transaction = null;
    IDbCmd IDbCmd;

    string EncryptedPassword = Encrypt(DataTO.txtPwd);
    Base dataAccCom = null;

    try
    {
        dataAccCom = Factory.Create();
        dataAccCom.OpenConnection();
        transaction = dataAccCom.BeginTransaction();
        IDbCmd = dataAccCom.CreateCommand("sp_Register", true);
        dataAccCom.AddParameter(IDbCmd, "op_Id", DbType.Int64, 0, ParameterDirection.Output);
        dataAccCom.AddParameter(IDbCmd, "p_dlstTitle", DbType.String, ReplaceNull(DataTO.dlstTitle));
        dataAccCom.AddParameter(IDbCmd, "p_txtFirstName", DbType.String, ReplaceNull(DataTO.txtFirstName));
        dataAccCom.AddParameter(IDbCmd, "p_txtMiddleName", DbType.String, ReplaceNull(DataTO.txtMiddleName));
        dataAccCom.AddParameter(IDbCmd, "p_txtLastName", DbType.String, ReplaceNull(DataTO.txtLastName));
        dataAccCom.AddParameter(IDbCmd, "p_txtDob", DbType.DateTime, DataTO.txtDob);
        dataAccCom.AddParameter(IDbCmd, "p_txtDesig", DbType.String, ReplaceNull(DataTO.txtDesig));
        dataAccCom.AddParameter(IDbCmd, "p_txtOFlatNo", DbType.String, ReplaceNull(DataTO.txtOFlatNo));
        dataAccCom.AddParameter(IDbCmd, "p_txtOBuild", DbType.String, ReplaceNull(DataTO.txtOBuild));
        dataAccCom.AddParameter(IDbCmd, "p_txtOPost", DbType.String, ReplaceNull(DataTO.txtOPost));
        dataAccCom.AddParameter(IDbCmd, "p_txtOArea", DbType.String, ReplaceNull(DataTO.txtOArea));
        dataAccCom.AddParameter(IDbCmd, "p_txtOCity", DbType.String, ReplaceNull(DataTO.txtOCity));
        dataAccCom.AddParameter(IDbCmd, "p_txtRBuild", DbType.String, ReplaceNull(DataTO.txtRBuild));
        dataAccCom.AddParameter(IDbCmd, "p_txtRPost", DbType.String, ReplaceNull(DataTO.txtRPost));
        dataAccCom.AddParameter(IDbCmd, "p_txtUserID", DbType.String,ReplaceNull(DataTO.txtUserID));
        dataAccCom.AddParameter(IDbCmd, "p_txtPwd", DbType.String, ReplaceNull(EncryptedPassword));
        dataAccCom.ExecuteNonQuery(IDbCmd);
        DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));
        transaction.Commit();
        return true;



    }
    catch (System.Exception ex)
    {
        if (transaction != null)
        {
            transaction.Rollback();
        }
        throw ex;
    }
    finally
    {
        transaction = null;
        if (dataAccCom != null)
        {
            dataAccCom.CloseConnection();
        }
        dataAccCom = null;
        IDbCmd = null;
    }
}

public string ReplaceNull(string value)
{
    if (value == null)
    {
        return "";
    }
    else
    {
        return value;
    }
}

public DateTime ReplaceNull(DateTime value)
{
    if (value == null)
    {
        return DateTime.Now;
    }
    else
    {
        return value;
    }
}

public double ReplaceNull(double value)
{
    if (value == null)
    {
        return 0.0;
    }
    else
    {
        return value;
    }
}

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

I’m thinking that your output parameter is coming back with a DBNull value. Add a check for that like this

var outputParam = dataAccCom.GetParameterValue(IDbCmd, "op_Id");
if(!(outputParam is DBNull))
     DataTO.Id = Convert.ToInt64(outputParam);

Method 2

I suspect that the line

DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));

is causing the problem. Is it possible that the op_Id value is being set to null by the stored procedure?

To Guard against it use the Convert.IsDBNull method. For example:

if (!Convert.IsDBNull(dataAccCom.GetParameterValue(IDbCmd, "op_Id"))
{
 DataTO.Id = Convert.ToInt64(dataAccCom.GetParameterValue(IDbCmd, "op_Id"));
}
else 
{
 DataTO.Id = ...some default value or perform some error case management
}

Method 3

You need to check for DBNull, not null. Additionally, two of your three ReplaceNull methods don’t make sense. double and DateTime are non-nullable, so checking them for null will always be false…

Method 4

TryParse is usually the most elegant way to handle this type of thing:

long temp = 0;
if (Int64.TryParse(dataAccCom.GetParameterValue(IDbCmd, "op_Id").ToString(), out temp))
{
   DataTO.Id = temp;
}

Method 5

Reason for the error: In an object-oriented programming language, null means the absence of a reference to an object. DBNull represents an uninitialized variant or nonexistent database column. Source:MSDN

Actual Code which I faced error:

Before changed the code:

    if( ds.Tables[0].Rows[0][0] == null ) //   Which is not working

     {
            seqno  = 1; 
      }
    else
    {
          seqno = Convert.ToInt16(ds.Tables[0].Rows[0][0]) + 1;
     }

After changed the code:

   if( ds.Tables[0].Rows[0][0] == DBNull.Value ) //which is working properly
        {
                    seqno  = 1; 
         }
            else
            {
                  seqno = Convert.ToInt16(ds.Tables[0].Rows[0][0]) + 1;
             }

Conclusion: when the database value return the null value, we recommend to use the DBNull class instead of just specifying as a null like in C# language.

Method 6

For others that arrive on this page from google:

DataRow also has a function .IsNull("ColumnName")

    public DateTime? TestDt; 
    public Parse(DataRow row)
    {
        if (!row.IsNull("TEST_DT"))
            TestDt = Convert.ToDateTime(row["TEST_DT"]);
    }

Method 7

I faced this problem today and resolved it by checking the mapping class. I had a class which had 5 properties to which 5 columns returned from stored procedure were being mapped. Those properties were non-nullable and due to which i was getting the error. I made them nullable and the issue resolved.

    public int? Pause { get; set; }
    public int? Delay { get; set; }
    public int? Transition { get; set; }
    public int? TransitionTime { get; set; }
    public int? TransitionResolution { get; set; }

Added “?” with data type to made them nullable.

Secondly i also added isNull check in the stored procedure as well as follows:

    isnull(co_pivot.Pause, 0) as Pause,
    isnull(co_pivot.Delay, 0) as Delay,
    isnull(co_pivot.Transition, 0) as Transition,
    isnull(co_pivot.TransitionTime, 0) as TransitionTime,
    isnull(co_pivot.TransitionResolution, 0) as TransitionResolution

Hope this helps someone.

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