Re: [Firebird-net-provider] Convert BLOB to string

[Martin <mc...@we...>]

Hi,

I have now tried the C# code below using the cast that was provided.
I still get an exception of

    "Specified cast is not valid."

the C# code that I have used is shown below. The stored procedure that I am
using is shown below also.
There is definatly a record comming back. at least if I use a fbdatareader
and loop then the loop only ueses a single record.
I am not sure how to get the value back from a data reader.
It seems strange that the cast works for you and not me I am using RC2.

Thanks again for any advice.

cheers

martin.

try
   {
    Context.Trace.Warn("Page_Load","Entered function");
    FirebirdSql.Data.Firebird.FbConnection objConn = new
FirebirdSql.Data.Firebird.FbConnection();
    FirebirdSql.Data.Firebird.FbCommand objCMD = new
FirebirdSql.Data.Firebird.FbCommand();
    objConn.ConnectionString =
"Database=C:\\Inetpub\\wwwroot\\nz\\_database\\RESTOREDB.GDB;User=SYSDBA;Pas
sword=masterkey;Dialect=3;Server=localhost;Pooling=false;";
    objConn.Open();
    objCMD.Connection = objConn;
    Context.Trace.Write("Page_Load","connection is open");
    objCMD.CommandText = "SP_EE_GET_GROUP_DESCRIPTION";
       objCMD.CommandType = CommandType.StoredProcedure;
    FirebirdSql.Data.Firebird.FbParameter P1 = new
FirebirdSql.Data.Firebird.FbParameter();
       P1.Direction = ParameterDirection.Input;
       P1 = objCMD.Parameters.Add("@ID", 87);
    FirebirdSql.Data.Firebird.FbDataReader dr;
    dr = objCMD.ExecuteReader();
    string value = (string)objCMD.ExecuteScalar();
    objConn.Close();
    Context.Trace.Warn("Page_Load","Exited function");
   }
   catch (Exception ex)
   {
    Context.Trace.Warn("Excepetion thrown");
    Context.Trace.Write(ex.Message);
   }

store procedure text

CREATE PROCEDURE SP_EE_GET_GROUP_DESCRIPTION (
    ID INTEGER)
RETURNS (
    DISPLAY_DESCRIPTION BLOB SUB_TYPE 0 SEGMENT SIZE 80)
AS
BEGIN
  FOR
    SELECT EE_SP_NAME.DISPLAY_DESCRIPTION
    FROM EE_SP_SCHEDULE
       INNER JOIN EE_SP_NAME ON (EE_SP_SCHEDULE.EE_SP_NAME_ID =
EE_SP_NAME.ID)
    WHERE
       (
          (EE_SP_SCHEDULE.ID = :ID)
       )
    INTO :DISPLAY_DESCRIPTION
  DO
  BEGIN
    SUSPEND;
  END
END






""Martin"" <mc...@we...> wrote in message
news:bu79g2$38v$1...@ne......
> Hi,
>
> I am using .net provider 1.5 RC2.
> I am using vb.net code. The line that is throwing the exception is
>
> strDesciption = CType(objCMD.ExecuteScalar(), String)
>
> and the exception description is
>
> Cast from type 'Byte()' to type 'String' is not valid.
>
> I have checked that a record is being broght back. Perhaps I have the cast
> syntax wrong...
>
> The full code that I am using is below. If I comment the cat out and just
> use
>
> objCMD.ExecuteScalar()
>
> then all works fine.
>
> I am executing a stored procedure. and the full code that I am using is
> below for reference.
>
>
> cheers
>
> martin.
>
>
>
> Try
>             Dim objConn As FirebirdSql.Data.Firebird.FbConnection = New
> FirebirdSql.Data.Firebird.FbConnection
>             Dim objCMD As FirebirdSql.Data.Firebird.FbCommand = New
> FirebirdSql.Data.Firebird.FbCommand
>             Dim objTran As FirebirdSql.Data.Firebird.FbTransaction
>             objConn.ConnectionString =
>
System.Configuration.ConfigurationSettings.AppSettings("DbConnectionString")
>             objConn.Open()
>             objCMD.Connection = objConn
>             objTran = objConn.BeginTransaction()
>             objCMD.Transaction = objTran
>             objCMD.CommandText = "SP_EE_GET_GROUP_DESCRIPTION"
>             objCMD.CommandType = CommandType.StoredProcedure
>             Dim P1 As New FirebirdSql.Data.Firebird.FbParameter
>             P1.Direction = ParameterDirection.Input
>             P1 = objCMD.Parameters.Add("@ID", 87)
>             Dim strDesciption As String 'Variable to hold the description
> string that will be returned
>
>             strDesciption = CType(objCMD.ExecuteScalar(), String)
> <<<<<<<<<<<<<<<<<<<<---------  THROWS EXCEPTION
>
>
>             objCMD.Dispose()
>             objTran.Commit()
>             objTran.Dispose()
>             objConn.Close()
>         Catch ex As Exception
>             Trace.Write(ex.Message())
>         End Try
>
>
>
>
>
>
> "Carlos Guzmán Álvarez" <car...@te...> wrote in message
> news:400...@te......
> > Hello:
> >
> > > BLOB SUB_TYPE 1 SEGMENT SIZE 80 CHARACTER SET NONE
> >
> > It's correct, which version of the .NET Data Provider are you using ??
> >
> > I have tested this with 1.5, and runs fine:
> >
> > FbConnection connection = new FbConnection(connectionString);
> > connection.Open();
> >
> > string sql = "select clob_field from test where int_field = 1";
> >
> > FbCommand command = new FbCommand(sql, connection);
> >
> > string value = (string)command.ExecuteScalar();
> >
> > connection.Close();
> >
> >
> >
> >
> > --
> > Best regards
> >
> > Carlos Guzmán Álvarez
> > Vigo-Spain
> >
> >
> >
> > -------------------------------------------------------
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> > See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
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> >
>
>
>
>
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