R/connect.R

In poissonconsulting/poissqlite: Work with SQLite Databases

#' Opens a connection to an sqlite database.
#'
#' The connection can be queried and closed using the functions
#' in the \code{DBI} package.
#'
#' @param file A string of the name of the file (without the file extension .sqlite).
#' @param dir A string of the directory.
#' @param new A flag indicating whether to enforce connection to an existing database (FALSE) or connection to a new database (TRUE).
#' @param foreign_keys A flag indicating whether to switch foreign keys on.
#' @param ask A flag indicating whether to ask before creating a new directory.
#' @export
ps_connect_sqlite <- function(file = "database", dir = ".", new = NA,
                              foreign_keys = TRUE,
                              ask = getOption("poissqlite.ask", TRUE)) {
  chk_string(file)
  chk_string(dir)
  chk_scalar(new)
  chk_vector(new)
  check_values(new,  c(TRUE, NA))
  chk_flag(foreign_keys)
  chk_flag(ask)

  if(dir != ".") {
    file %<>% file.path(dir, .)
  }

  if(identical(tools::file_ext(file), ""))
    file %<>% paste0(".sqlite")

  if (identical(new, FALSE) && !file.exists(file))
    ps_error("file '", file, "' does not exist")

  if (identical(new, TRUE) && file.exists(file)) {
    if(ask && !yesno::yesno("Delete existing file '", file, "'"))
      ps_error("file '", file, "' already exists")
    file.remove(file)
  }
  if (!poisutils::ps_create_dir(dir, ask)) error("dir '", dir, "' does not exist")

  conn <- DBI::dbConnect(RSQLite::SQLite(), file)
  if (foreign_keys) DBI::dbGetQuery(conn, "PRAGMA foreign_keys = ON;")
  conn
}

#' Close a connection to an sqlite database.
#'
#' A wrapper on DBI::dbDisconnect.
#'
#' @param conn The connection to close.
#' @export
ps_disconnect_sqlite <- function(conn) {
  DBI::dbDisconnect(conn)
}