Add a zip attachment example (#922)

inst/plumber/16-attachment/plumber.R

@@ -21,3 +21,30 @@ function() {
 function() {
   Sys.time()
 }
+
+
+#* Write and return multiple files as an archive. Ex: `datasets.zip`
+#* @serializer octet
+#* @get /datasets
+function() {
+
+  # Create temporary directory structure
+  tmp_dir <- tempfile()
+  dir.create(tmp_dir, showWarnings = FALSE)
+  on.exit(unlink(tmp_dir, recursive = TRUE), add = TRUE)
+
+  # Save datasets to csv
+  csv_files <- lapply(c("mtcars", "quakes", "airquality"), function(dataset) {
+    csv_file <- file.path(tmp_dir, paste0(dataset, ".csv"))
+    write.csv(get(dataset), csv_file)
+    csv_file
+  })
+
+  # Create archive
+  zip_file <- file.path(tmp_dir, "datasets.zip")
+  zip(zip_file, csv_files, flags = "-jq9X")
+  val <- readBin(zip_file, "raw", file.info(zip_file)$size)
+
+  as_attachment(val, "datasets.zip")
+
+}