Merge pull request #223 from ThomasSoeiro/main

R/csv.R

@@ -5,6 +5,7 @@
 #'
 #' @inheritParams duckdb_register
 #' @param files One or more CSV file names, should all have the same structure though
+#' @param ... Reserved for future extensions, must be empty.
 #' @param header Whether or not the CSV files have a separate header in the first line
 #' @param na.strings Which strings in the CSV files should be considered to be NULL
 #' @param nrow.check How many rows should be read from the CSV file to figure out data types
@@ -14,7 +15,7 @@
 #' @param lower.case.names Transform column names to lower case
 #' @param sep Alias for delim for compatibility
 #' @param transaction Should a transaction be used for the entire operation
-#' @param ... Passed on to [read.csv()]
+#' @param temporary Set to `TRUE` to create a temporary table
 #' @return The number of rows in the resulted table, invisibly.
 #' @export
 #' @examplesIf duckdb:::TEST_RE2
@@ -29,9 +30,24 @@
 #' dbReadTable(con, "data")
 #'
 #' dbDisconnect(con)
-duckdb_read_csv <- function(conn, name, files, header = TRUE, na.strings = "", nrow.check = 500,
-                            delim = ",", quote = "\"", col.names = NULL, lower.case.names = FALSE, sep = delim, transaction = TRUE, ...) {
-  #
+duckdb_read_csv <- function(
+  conn,
+  name,
+  files,
+  ...,
+  header = TRUE,
+  na.strings = "",
+  nrow.check = 500,
+  delim = ",",
+  quote = "\"",
+  col.names = NULL,
+  lower.case.names = FALSE,
+  sep = delim,
+  transaction = TRUE,
+  temporary = FALSE
+) {
+  # FIXME: Warning as of duckdb 1.1.1, turn this into an error later
+  if (...length() > 0) warning("Arguments passed to ... are currently not used")
   if (length(na.strings) > 1) stop("na.strings must be of length 1")
   if (!missing(sep)) delim <- sep
 
@@ -67,7 +83,7 @@ duckdb_read_csv <- function(conn, name, files, header = TRUE, na.strings = "", n
       }
       names(headers[[1]]) <- col.names
     }
-    dbWriteTable(conn, tablename, headers[[1]][FALSE, , drop = FALSE])
+    dbCreateTable(conn, tablename, headers[[1]], temporary = temporary)
   }
 
   for (i in seq_along(files)) {

tests/testthat/test-read.R

@@ -126,5 +126,17 @@ test_that("duckdb_read_csv() works as expected", {
     read.csv(tf3, na.strings = "-")
   )
 
+  # temporary table
+  # see https://github.com/duckdb/duckdb-r/issues/142
+  db <- tempfile()
+  con2 <- dbConnect(duckdb(), dbdir = db)
+  duckdb_read_csv(con2, "iris", tf, temporary = TRUE)
+  expect_true(length(dbListTables(con2)) == 1)
+  dbDisconnect(con2)
+
+  con2 <- dbConnect(duckdb(), dbdir = db)
+  expect_true(length(dbListTables(con2)) == 0)
+  dbDisconnect(con2)
+
   dbDisconnect(con, shutdown = TRUE)
 })