Add simplify parameter

R/reader.R

@@ -2,28 +2,38 @@
 #'
 #' Utility to read BSON data into R without MongoDB. Useful to read a dump from
 #' from a `mongoexport` dump if it fits in memory. This utility does not attempt
-#' to convert data into a data.frame: the output is a vector with length of the
-#' total number of documents in the bson collection.
+#' to convert result into one giant data.frame: the output is a vector of length
+#' equal to total number of documents in the bson collection. However it is
+#' possible to simplify the separate data objects using [jsonlite][fromJSON] rules,
+#' to recognize atomic vectors and data frames in nested bson documents.
 #'
-#' Alternatively, to import a bson dump into your local mongodb server, use the
-#' [mongo$import][mongo] function instead. This requires little memory and once
-#' data is in mongo you can easily query it.
+#' An alternative to this function is to import your bson dump into a local mongodb
+#' server using the [mongo$import][mongo] function. This requires little memory
+#' and once data is in mongodb you can easily query and manipulate it using this
+#' package.
 #'
 #' @export
 #' @useDynLib mongolite R_bson_reader_file
 #' @param file path or url to a bson file
 #' @param as_json read data into json strings instead of R lists.
+#' @param simplify should nested data get simplified into atomic vectors and
+#' dataframes where possible? See details.
 #' @param verbose print some progress output while reading
 #' @examples
 #' diamonds <- read_bson("https://jeroen.github.io/data/diamonds.bson")
 #' length(diamonds)
-read_bson <- function(file, as_json = FALSE, verbose = interactive()){
+read_bson <- function(file, as_json = FALSE, simplify = TRUE, verbose = interactive()){
   if(grepl("^https?://", file)){
     file_url <- file
     file <- tempfile()
     on.exit(unlink(file))
     curl::curl_download(file_url, file, quiet = !isTRUE(verbose))
   }
   file <- normalizePath(file, mustWork = TRUE)
-  .Call(R_bson_reader_file, file, as_json, verbose)
+  out <- .Call(R_bson_reader_file, file, as_json, verbose)
+  if(!isTRUE(simplify))
+    return(out)
+  if(verbose)
+    cat("Simplifying data...\n", file = stderr())
+  lapply(out, jsonlite:::simplify)
 }