public PqsqlLargeObject(PqsqlConnection conn)
{
#if CODECONTRACTS
Contract.Requires <ArgumentNullException>(conn != null);
#else
if (conn == null)
{
throw new ArgumentNullException(nameof(conn));
}
#endif
// All large object manipulation using these functions must take place within an SQL transaction block,
// since large object file descriptors are only valid for the duration of a transaction.
// https://www.postgresql.org/docs/current/static/lo-interfaces.html
PGTransactionStatusType transactionStatus = conn.TransactionStatus;
if (transactionStatus != PGTransactionStatusType.PQTRANS_INTRANS &&
transactionStatus != PGTransactionStatusType.PQTRANS_ACTIVE)
{
throw new PqsqlException("PqsqlLargeObject manipulation must take place within an SQL transaction");
}
mConn = conn;
mPGConn = conn.PGConnection;
if (mPGConn == IntPtr.Zero)
{
throw new ArgumentNullException("PqsqlConnection is closed: " + mConn.GetErrorMessage());
}
mOid = 0;
mFd = -1;
mMode = 0;
mPos = -1;
}
// Summary:
// Commits the database transaction.
public override void Commit()
{
ExecStatusType s = SaveTransaction(true);
switch (s)
{
case ExecStatusType.PGRES_COMMAND_OK:
return;
case ExecStatusType.PGRES_EMPTY_QUERY:
throw new PqsqlException("Cannot commit: connection or transaction is closed");
default:
string err = mConn.GetErrorMessage();
throw new PqsqlException("Could not commit transaction: " + err);
}
}
public uint Create()
{
// returns 0 (InvalidOid) on error
uint ret = PqsqlWrapper.lo_create(mPGConn, 0);
if (ret == 0)
{
throw new PqsqlException("Could not create large object: " + mConn.GetErrorMessage());
}
return(ret);
}
public virtual void Start()
{
#if CODECONTRACTS
Contract.Requires <InvalidOperationException>(
!string.IsNullOrWhiteSpace(Table) || !string.IsNullOrWhiteSpace(QueryInternal),
"Table and Query properties are null.");
#else
if (string.IsNullOrWhiteSpace(Table) && string.IsNullOrWhiteSpace(QueryInternal))
{
throw new InvalidOperationException("Table and Query properties are null.");
}
#endif
// PQexec does not set field types in PQresult for COPY FROM statements,
// just retrieve 0 rows for the field types of Table or Query
// TODO use PqsqlCopyColumnsCollection for ColumnList
StringBuilder sb = new StringBuilder();
if (!SuppressSchemaQueryInternal)
{
if (QueryInternal == null)
{
sb.AppendFormat("SELECT {0} FROM {1} LIMIT 0;", (object)ColumnList ?? '*', Table);
}
else
{
sb.AppendFormat("{0} LIMIT 0;", QueryInternal);
}
// fetch number of columns and store column information
using (PqsqlCommand cmd = new PqsqlCommand(mConn))
{
cmd.CommandText = sb.ToString();
cmd.CommandType = CommandType.Text;
cmd.CommandTimeout = CopyTimeout;
using (PqsqlDataReader r = cmd.ExecuteReader(CommandBehavior.Default))
{
// just pick current row information
PqsqlColInfo[] src = r.RowInformation;
if (src == null)
{
throw new PqsqlException("Cannot retrieve RowInformation for '" +
QueryInternal ?? Table + "'.");
}
mColumns = src.Length;
mRowInfo = new PqsqlColInfo[mColumns];
Array.Copy(src, mRowInfo, mColumns);
}
}
sb.Clear();
}
// now build COPY FROM statement
sb.Append("COPY ");
if (QueryInternal == null)
{
sb.AppendFormat("{0} ", Table);
// always create list of columns if not SuppressSchemaQuery
if (string.IsNullOrEmpty(ColumnList))
{
if (!SuppressSchemaQueryInternal)
{
// just assume that we use standard table order
sb.AppendFormat("({0})", string.Join(",", mRowInfo.Select(r => r.ColumnName)));
}
}
else
{
// let user decide the column order
sb.AppendFormat("({0})", ColumnList);
}
}
else
{
sb.AppendFormat("({0})", QueryInternal);
}
sb.AppendFormat(" {0} BINARY", CopyStmtDirection);
byte[] q = PqsqlUTF8Statement.CreateUTF8Statement(sb);
IntPtr res;
ExecStatusType s = mConn.Exec(q, out res);
// result buffer should contain column information and PGconn should be in COPY_IN state
if (res == IntPtr.Zero || s != QueryResultType)
{
mConn.Consume(res); // we might receive several results...
throw new PqsqlException("Could not execute statement «" + sb + "»: " + mConn.GetErrorMessage());
}
// check first column format, current implementation will have all columns set to binary
if (PqsqlWrapper.PQfformat(res, 0) == 0)
{
mConn.Consume(res);
throw new PqsqlException("PqsqlCopyFrom only supports BINARY format.");
}
var nFields = PqsqlWrapper.PQnfields(res);
if (SuppressSchemaQueryInternal)
{
mColumns = nFields;
}
else
{
// sanity check
if (mColumns != nFields)
{
mConn.Consume(res);
throw new PqsqlException("Received wrong number of columns for " + sb);
}
}
// done with result inspection
PqsqlWrapper.PQclear(res);
}
