add error handling if directories are empty or do not exist

R/fetch.R

@@ -30,17 +30,50 @@ fetch_batch <- function(offset, download_dir) {
 # TODO: error handling
 # - what if: page not reachable
 # - wrong format, etc.
-fetch_all <- function(download_dir="records/") {
+
+#' Download available records
+#'
+#' This fetches all available records of the 19th legislative period of the german Bundestag.
+#'
+#' @param download_dir character
+#'
+#' @export
+fetch_all <- function(download_dir="records/", create=FALSE) {
+    # check if download_dir path is a directory path
+    if (str_sub(download_dir, -1) != .Platform$file.sep)
+        download_dir <- str_c(download_dir, .Platform$file.sep)
+
+    # check if download_dir exists
+    if(file.access(download_dir, mode=0) == -1) {
+        if (create) {
+            tryCatch(dir.create(download_dir),
+                     error = stop_dir_not_creatable,
+                     warning = stop_dir_not_creatable)
+        } else {
+            stop("Directory does not exist. Use create = TRUE if you wish to create the directory.")
+        }
+    } else if (file.access(download_dir, mode=2) == -1) {
+        stop("Directory exists, but is not writeable.")
+    }
     cat("Fetching all available records from bundestag.de. This may take a while ...\n")
-    
+
     # create progress bar
     pb <<- timerProgressBar(min=0, max=250, width=40, char="+")
     progress <<- 0
     # close progress bar on exit (also on error)
     on.exit({close(pb); cat("Done.\n")})
+
     # fetch batch by batch
     offset <- 0
     while(fetch_batch(offset, download_dir)) offset <- offset + 10
+
     # if successful, set progressbar to 100%
     setTimerProgressBar(pb, 250)
 }
+
+stop_dir_not_creatable <- function(cond) {
+    # currently this has call: dir.create(download_dir)
+    # do we want to change this to fetch_all(...) ?
+    cond$message <- "Directory does not exist and can't be created. Probably because the path is not writeable."
+    stop(cond)
+}