dlib C++ Library - sqlite_tools.h

    // Copyright (C) 2011  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_SQLiTE_TOOLS_H_
    #define DLIB_SQLiTE_TOOLS_H_

    #include "sqlite_tools_abstract.h"
    #include "sqlite.h"

    // ----------------------------------------------------------------------------------------

    namespace dlib
    {

        class transaction : noncopyable
        {
        public:
            transaction (
                database& db_
            ) :
                db(db_),
                committed(false)
            {
                db.exec("begin transaction");
            }

            void commit ()
            {
                if (!committed)
                {
                    committed = true;
                    db.exec("commit");
                }
            }

            ~transaction() noexcept(false)
            {
                if (!committed)
                    db.exec("rollback");
            }

        private:
            database& db;
            bool committed;

        };

    // ----------------------------------------------------------------------------------------

        template <
            typename T
            >
        void query_object (
            database& db,
            const std::string& query,
            T& item
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                st.get_column_as_object(0,item);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

        inline std::string query_text (
            database& db,
            const std::string& query
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                const std::string& temp = st.get_column_as_text(0);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
                return temp;
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

        inline double query_double (
            database& db,
            const std::string& query
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                double temp = st.get_column_as_double(0);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
                return temp;
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

        inline int query_int (
            database& db,
            const std::string& query
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                int temp = st.get_column_as_int(0);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
                return temp;
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

        inline int64 query_int64 (
            database& db,
            const std::string& query
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                int64 temp = st.get_column_as_int64(0);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
                return temp;
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

        inline const std::vector<char> query_blob (
            database& db,
            const std::string& query
        )
        {
            statement st(db, query);
            st.exec();
            if (st.move_next() && st.get_num_columns() == 1)
            {
                const std::vector<char>& temp = st.get_column_as_blob(0);
                if (st.move_next())
                    throw sqlite_error("query doesn't result in exactly 1 element");
                return temp;
            }
            else
            {
                throw sqlite_error("query doesn't result in exactly 1 element");
            }
        }

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_SQLiTE_TOOLS_H_