R/ds_versions.R

In bernhard-da/datastore: Creates a datastore which can contain versioned datasets

#' ds_versions
#'
#' returns a data.frame (or \code{NULL}) containing information on all versions of the requested data-object given by argument \code{ds_name}
#'
#' @param ds path to datastore
#' @param ds_name name of data-object
#' @param verbose (logical) if TRUE, additional messages will be printed to prompt
#'
#' @return a \code{data.frame} or \code{NULL}
#' @export
#'
#' @examples
#' ## not yet
ds_versions <- function(ds, ds_name, verbose=TRUE) {
  ds_isvalid(ds)
  stopifnot(is_scalar_logical(verbose))

  res <- ds_read_index(ds)
  if (!is.data.frame(res$info)) {
    if (verbose) {
      message(paste("no files in datastore", shQuote(ds_info(ds, verbose = FALSE)$ds_name), "--> please use ds_add()"))
    }
    return(invisible(NULL))
  }
  if (!ds_name %in% res$datasets) {
    if (verbose) {
      message(paste(shQuote(ds_name), "not in datastore"))
    }
    return(invisible(NULL))
  }

  info <- res$info
  info$version <- as.numeric(info$version)
  info[info$ds_name == ds_name, , drop = FALSE]
}