Error informatively if no packets found

Fixes #144

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: orderly2
 Title: Orderly Next Generation
-Version: 1.99.17
+Version: 1.99.18
 Authors@R: c(person("Rich", "FitzJohn", role = c("aut", "cre"),
                     email = "[email protected]"),
              person("Robert", "Ashton", role = "aut"),

R/location.R

@@ -313,6 +313,23 @@ orderly_location_pull_packet <- function(..., options = NULL, recursive = NULL,
     ids <- orderly_search(..., options = options, root = root)
   }
 
+  if (length(ids) == 0) {
+    if (options$allow_remote && !options$pull_metadata) {
+      pull_arg <- gsub(" ", "\u00a0", "options = list(pull_metadata = TRUE)")
+      hint <- c(i = paste("Did you forget to pull metadata? You can do this",
+                          "by using the argument '{pull_arg}' in the call",
+                          "to 'orderly_location_pull_packet()', or",
+                          "by running 'orderly_location_pull_metadata()'"))
+    } else {
+      hint <- NULL
+    }
+    cli::cli_abort(
+      c("No packets found in query, so cannot pull anything",
+        i = paste("Your query returned no packets, which is probably a mistake",
+                  "so I'm erroring here."),
+        hint))
+  }
+
   plan <- location_build_pull_plan(ids, options$locations, recursive, root,
                                    call = environment())
 

tests/testthat/test-location.R

@@ -392,6 +392,21 @@ test_that("can pull a packet from one location to another, using file store", {
 })
 
 
+test_that("can error where a query returns no packets", {
+  root <- list()
+  for (name in c("src", "dst")) {
+    root[[name]] <- create_temporary_root()
+  }
+
+  id <- create_random_packet(root$src)
+  orderly_location_add("src", "path", list(path = root$src$path),
+                       root = root$dst)
+  err <- expect_error(
+    orderly_location_pull_packet(name = "data", root = root$dst),
+    "No packets found in query, so cannot pull anything")
+})
+
+
 test_that("can pull a packet from one location to another, archive only", {
   root <- list()
   for (name in c("src", "dst")) {