nanodbcParser.cpp

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/***************************************************************************
 *   Copyright (c) 2005-2024 by Christophe GONZALES(_at_AMU) and Pierre-Henri WUILLEMIN(_at_LIP6)  *
 *   info_at_agrum_dot_org                                               *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
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 ***************************************************************************/
 
#include <agrum/base/database/nanodbcParser.h>
 
#ifdef _ODBC
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS

#  ifdef GUM_NO_INLINE
#    include <agrum/base/database/nanodbcParser_inl.h>
#  endif /* GUM_NO_INLINE */
 
namespace gum {
 
  namespace learning {
    NanodbcParser::NanodbcParser() { GUM_CONSTRUCTOR(NanodbcParser); }
 

    NanodbcParser::NanodbcParser(nanodbc::connection& connexion, const std::string& query) {
      // check if there is a connection. If so, execute the query
      if (connexion.connected()) {
        _result_ = nanodbc::execute(connexion, query);
        _data_.resize(std::size_t(_result_.columns()));
      }
      GUM_CONSTRUCTOR(NanodbcParser);
    }
 

    NanodbcParser::~NanodbcParser() { GUM_DESTRUCTOR(NanodbcParser); }
 

    bool NanodbcParser::next() {
      /* Extract from sql.h:
         SQL data type codes
         #define SQL_UNKNOWN_TYPE    0
         #define SQL_CHAR            1
         #define SQL_NUMERIC         2
         #define SQL_DECIMAL         3
         #define SQL_INTEGER         4
         #define SQL_SMALLINT        5
         #define SQL_FLOAT           6
         #define SQL_REAL            7
         #define SQL_DOUBLE          8
         #if (ODBCVER >= 0x0300)
         #define SQL_DATETIME        9
         #endif
         #define SQL_VARCHAR        12 */
      try {
        if (_result_.next()) {
          const std::size_t nb_cols = std::size_t(_result_.columns());
          char              str[100];   // buffer for retrieving floats
          for (std::size_t i = 0; i < nb_cols; ++i) {
            const short pos(i);
            try {
              const int type = _result_.column_datatype(pos);
 
              // if the column contains a numeric field, we should use
              // method get<float>, otherwise a get<string> should be ok
              // WARNING: using a get<string> to get the content of a
              // real-valued field will provide incorrect results
              if ((type >= SQL_NUMERIC) && (type <= SQL_DOUBLE)) {
                snprintf(str, 100, "%g", _result_.get< float >(pos));
                _data_[i] = str;
              } else {
                _data_[i] = _result_.get< std::string >(pos);
              }
            } catch (nanodbc::null_access_error& e) { _data_[i] = "NULL"; }
          }
          ++_nb_line_;
          return true;
        }
      } catch (std::runtime_error& e) { GUM_ERROR(DatabaseError, std::string(e.what())) }
      _data_.clear();
      return false;
    }

    void NanodbcParser::useNewQuery(nanodbc::connection& connexion, const std::string& query) {
      _result_ = nanodbc::execute(connexion, query);
      _data_.resize(std::size_t(_result_.columns()));
      _nb_line_ = std::size_t(0);
    }
 
 
  } /* namespace learning */
 
} /* namespace gum */
 
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
#endif // _ODBC