Update download.R to allow year vectors for baci data (#250)

* Update download.R to allow year vectors for baci data 

Ensures 'path' is the single url in 'param$url' for baci source in external_download.

* download: fixing str_replace error more generally

now this won't happen for baci, but also for other functions

---------

Co-authored-by: Igor Rigolon <[email protected]>

R/download.R

@@ -338,17 +338,19 @@ external_download <- function(dataset = NULL, source = NULL, year = NULL,
   # Some URLs are in the form www.data/$year$_$dataset$.csv, where expression
   # surrounded by $ are placeholders. The code below subs them in for actual parameters
 
-  if (!is.null(param$year)) {
-    path <- path %>%
-      stringr::str_replace("\\$year\\$", as.character(param$year))
-  }
-  if (!is.null(param$state)) {
-    path <- path %>%
-      stringr::str_replace("\\$state\\$", param$state)
-  }
-  if (!is.null(param$file_name)) {
-    path <- path %>%
-      stringr::str_replace("\\$file_name\\$", param$file_name)
+  if (stringr::str_detect(path, "\\$year\\$|\\$state\\$|\\$file_name\\$")) {
+    if (!is.null(param$year)) {
+      path <- path %>%
+        stringr::str_replace("\\$year\\$", as.character(param$year))
+    }
+    if (!is.null(param$state)) {
+      path <- path %>%
+        stringr::str_replace("\\$state\\$", param$state)
+    }
+    if (!is.null(param$file_name)) {
+      path <- path %>%
+        stringr::str_replace("\\$file_name\\$", param$file_name)
+    }
   }
 
   # Below are the exceptions, for which manipulation is needed