query.h

/*
 * query.h
 * This file is part of dbPager Classes Library (DCL)
 *
 * Copyright (c) 2008 Dennis Prochko <wolfsoft@mail.ru>
 *
 * DCL 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 version 3.
 *
 * DCL 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 DCL; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

#ifndef _QUERY_H_
#define _QUERY_H_

#include <string>
#include <vector>

#ifdef _WIN32
#include <windows.h>
#include <odbcinst.h>
#endif

#include <sqltypes.h>
#include <sql.h>
#include <sqlext.h>

#include <dcl/connection.h>
#include <dcl/exception.h>
#include <dcl/strutils.h>

namespace dbp {
namespace odbc {


class query_exception: public dbp::exception {
public:
        query_exception(const std::string &msg): exception(msg) { }
};


class query {
public:

        class parameter {
        public:
                std::string name;
                std::string value;
        };
        typedef std::vector<parameter> parameters;

        class field {
        public:
                field(query *parent = NULL): _query(parent) { };
                int number;
                std::string name;
                std::string get_value() const;
        private:
                query *_query;
        };
        typedef std::vector<field> fields;
        class flush { };

        query(const connection &connection);

        virtual ~query();

        parameters& prepare(const std::string &statement);

        query& operator()(const std::string &statement);

        const fields& execute();

        const fields& execute(const std::string &statement);

        bool next();
        void set_parameter(int num, int value);
        void set_parameter(int num, double value);
        void set_parameter(int num, const std::string &value);

        template<class T>
        query& operator<<(const T &parameter) {
                set_parameter(_prmcnt, parameter);
                _prmcnt++;
                return *this;
        };
        void get_field(int num, int &value);
        void get_field(int num, double &value);
        void get_field(int num, std::string &value);
        template<class T>
        query& operator>>(T &var) {
                get_field(_fldcnt, var);
                _fldcnt++;
                return *this;
        };
private:
        const connection &_db;
        int _prmcnt, _fldcnt;
        SQLHSTMT stmt;
        parameters _parameters;
        fields _fields;
        // Obtain the last diagnostic (error) message from ODBC system
        std::string get_error() const;
        // Retrieve resultset metadata after query executing
        void retrieve_metadata();
        void set_parameter(int num, const flush &value);
        // Parse the query, filling the parameter list and reconstruct the statement
        std::string parse(const std::string &statement);
};

}} // namespace

#endif /*_QUERY_H_*/