R/default.R

In rstats-db/RPostgres: C++ Interface to PostgreSQL

#' Check if default database is available.
#'
#' RPostgres examples and tests connect to a default database via
#' `dbConnect(`[RPostgres::Postgres()]`)`. This function checks if that
#' database is available, and if not, displays an informative message.
#'
#' @param ... Additional arguments passed on to [dbConnect()]
#' @export
#' @examples
#' if (postgresHasDefault()) {
#'   db <- postgresDefault()
#'   print(dbListTables(db))
#'   dbDisconnect(db)
#' } else {
#'   message("No database connection.")
#' }
postgresHasDefault <- function(...) {
  tryCatch(
    {
      con <- connect_default(...)
      dbDisconnect(con)
      TRUE
    },
    error = function(...) {
      message(
        "Could not initialise default postgres database. If postgres is running\n",
        "check that the environment variables PGHOST, PGPORT, \n",
        "PGUSER, PGPASSWORD, and PGDATABASE, are defined and\n",
        "point to your database."
      )
      FALSE
    })
}

#' @description
#' `postgresDefault()` works similarly but returns a connection on success and
#' throws a testthat skip condition on failure, making it suitable for use in
#' tests.
#' @export
#' @rdname postgresHasDefault
postgresDefault <- function(...) {
  tryCatch(
    {
      connect_default(...)
    },
    error = function(...) {
      testthat::skip("Test database not available")
    })
}

connect_default <- function(...) {
  dbConnect(Postgres(), ...)
}