#' PostgreSQL - Create a connection object
#' @details Ühenduse loomine PostgreSql andmebaasiga.
#' @param host Name or the numeric IPaddress of the host to connect to.
#' @param dbname The database name.
#' @param user PostgreSQL user name to connect as. Defaults to be the same as the operating system name of the user running the application.
#' @param password Password to be used if the server demands password authentication.
#' @param port Port number to connect to at the server host.
#' @param type Connection type "RPostgres" or "RPostgreSQL". RPostgres is default.
#' @return return message.
#' @seealso \code{\link{myPostgresConnect}}, \code{\link{myPostgresDropTable}},
#' \code{\link{myPostgresCreateGisDb}}, \code{\link{myPostgresImprotShp}}
#' @examples \dontrun{
#' con <- myPostgresConnect(host = '192.168.255.26', port = 5432,
#'        user = 'osm', password = 'osm', dbname = 'shp')
#'
#' }
#'
#' @export
#'

myPostgresConnect <- function(host = '192.168.255.26', port = 5432,
                              user = 'osm', password = 'osm', dbname = 'shp',
                              type = c("RPostgres", "RPostgreSQL")) {
  con = NULL
  if(length(type)>1) type <- type[1]
  driver <- RPostgres::Postgres()
  if(tolower(type)=="rpostgresql") driver <- RPostgreSQL::PostgreSQL()
  try(con <- DBI::dbConnect(driver, host = host, port = port, user = user, password = password, dbname = dbname),
      silent = FALSE)
  # Check is connection valid
  #  DBI::dbIsValid(con) - see ei toimi RPostgreSQL ühenduse korral.
  if(is.null(con)){
    message(paste0("DB connection is not valid!"))
    return()
  }
  con
}