Retrieve image from Oracle DB

问题

So, i am using a web api to retrieve a image!! But, at the DB the image is a LongRaw. Im seeing at the google that i need to use the OracleDbType.Blob But, when i try to use this,

public IEnumerable<FotoEnvolvido> GetFoto(string suspid)
        {

            DataSet lretorno = new DataSet();

            string connectionString = GetConnectionString();
            using (OracleConnection connection = new OracleConnection())
            {
                connection.ConnectionString = connectionString;

                OracleDataReader reader = null;
                OracleCommand cmd = new OracleCommand();
                cmd.InitialLONGFetchSize = 50000;
                cmd.Connection = connection;
                cmd = new OracleCommand("MOBILE.XAPIMANDADOMOBILE.BUSCAFOTO", connection);
                cmd.CommandType = CommandType.StoredProcedure;

                //variáveis entrada            
                cmd.Parameters.Add(new OracleParameter("SUSPID", suspid));
                //variáveis de saida          
                cmd.Parameters.Add(new OracleParameter("oretorno", OracleDbType.Blob)).Direction = ParameterDirection.Output;

                connection.Open();
                cmd.ExecuteNonQuery();
                OracleDataAdapter da = new OracleDataAdapter(cmd);

                da.Fill(lretorno); 

                reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);

                //CRIO A LISTA
                lretorno.Load(reader, LoadOption.OverwriteChanges, "BUSCAFOTO");
                connection.Close();
                connection.Dispose();

                var teste = lretorno.Tables[0].AsEnumerable().Select(row => new FotoEnvolvido
                {
                    FOTO = (byte[])(row["FOTO"]),
                });

                return teste;
            }
        }

i have a error on cmd.ExecuteNonQuery() :

"ORA-06550: linha 1, coluna 7:\nPLS-00306: número errado ou tipos de argumentos na chamada para 'BUSCAFOTO'\nORA-06550: linha 1, coluna 7:\nPL/SQL: Statement ignored"

Oracle.ManagedDataAccess.Client.OracleException was unhandled by user code
  DataSource=""
  ErrorCode=-2147467259
  HResult=-2147467259
  IsRecoverable=false
  Message=ORA-06550: linha 1, coluna 7:
PLS-00306: número errado ou tipos de argumentos na chamada para 'BUSCAFOTO'
ORA-06550: linha 1, coluna 7:
PL/SQL: Statement ignored
  Number=6550
  Procedure=""
  Source=Oracle Data Provider for .NET, Managed Driver
  StackTrace:
       em OracleInternal.ServiceObjects.OracleCommandImpl.VerifyExecution(OracleConnectionImpl connectionImpl, Int32& cursorId, Boolean bThrowArrayBindRelatedErrors, OracleException& exceptionForArrayBindDML, Boolean& hasMoreRowsInDB, Boolean bFirstIterationDone)
       em OracleInternal.ServiceObjects.OracleCommandImpl.VerifyExecution(OracleConnectionImpl connectionImpl, Int32& cursorId, Boolean bThrowArrayBindRelatedErrors, OracleException& exceptionForArrayBindDML, Boolean bFirstIterationDone)
       em OracleInternal.ServiceObjects.OracleCommandImpl.ExecuteNonQuery(String commandText, OracleParameterCollection paramColl, CommandType commandType, OracleConnectionImpl connectionImpl, Int32 longFetchSize, Int64 clientInitialLOBFS, OracleDependencyImpl orclDependencyImpl, Int64[]& scnFromExecution, OracleParameterCollection& bindByPositionParamColl, Boolean& bBindParamPresent, OracleException& exceptionForArrayBindDML, Boolean isFromEF)
       em Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteNonQuery()
       em WebApiApp.Controllers.FotoController.GetFoto(String suspid) na C:\Users\50216740\Documents\Visual Studio 2015\Projects\AppMobilePCRJ\AppMobilePCRJ\WebApiApp\Controllers\FotoController.cs:linha 49
       em lambda_method(Closure , Object , Object[] )
       em System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
       em System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)
       em System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)
  InnerException: 

If i use OracleDbType.RefCursor like the others web apis that i get strings, don´t give me this error...the problem is that the parameter comes [{"ISUSPID":0,"FOTO":""}], even when on DB brings me the image!

What i am doind wrong, thats the FOTO is empty on Json ???

回答1:

I'm not sure what lretorno.Load(...) is doing to read the data, but this sudo code sample using a select statement might help you... I've always had to specifically get the blob and read it out to get the bytes in the past.

Example for retrieving a LONG RAW DataType

var imgCmd = new OracleCommand("SELECT photo FROM photos WHERE photo_id = 1", _con);
imgCmd.InitialLONGFetchSize = -1; // Retrieve the entire image during select instead of possible two round trips to DB
var reader = imgCmd.ExecuteReader();
if (reader.Read()) {
    // Fetch the LONG RAW
    OracleBinary imgBinary = reader.GetOracleBinary(0);
    // Get the bytes from the binary obj
    byte[] imgBytes = imgBinary.IsNull ? null : imgBinary.Value;
}
reader.Close();

Example for retrieving a BLOB DataType

var imgCmd = new OracleCommand("SELECT photo FROM photos WHERE photo_id = 1", _con);
var reader = imgCmd.ExecuteReader();
if (reader.Read()) {
    // Fetch the blob
    OracleBlob imgBlob = reader.GetOracleBlob(0);
    // Create byte array to read the blob into
    byte[] imgBytes = new byte[imgBlob.Length];
    // Read the blob into the byte array
    imgBlob.Read(imgBytes, 0, imgBlob.Length);
}
reader.Close();

来源：https://stackoverflow.com/questions/39045383/retrieve-image-from-oracle-db