Change default schemaLocation so it points at a URL

R/as_xml.R

@@ -25,21 +25,21 @@
 #' @return a xml_document object. Or if a file path is provided, the metadata
 #' is written out in XML file and the function returns `NULL` invisibly.
 as_xml <- function(x, file=NULL, root = "eml", ns = "eml",
-  schemaLocation = paste0(eml_ns(), "/ eml.xsd"))
+  schemaLocation = eml_schema_location())
   {
     UseMethod("as_xml")
   }
 
 #' @export
 as_xml.list <- function(x, file=NULL, root = "eml", ns = "eml",
-                        schemaLocation = paste0(eml_ns(), "/ eml.xsd")){
+                        schemaLocation = eml_schema_location()){
   x <- as_emld.list(x)
   as_xml.emld(x, file)
 }
 
 #' @export
 as_xml.emld <- function(x, file=NULL, root = "eml", ns = "eml",
-                        schemaLocation = paste0(eml_ns(), "/ eml.xsd")){
+                        schemaLocation = eml_schema_location()){
   ## Frame/compact into original context for a standardized structure
   x <- eml_frame(x)
 

R/eml_version.R

@@ -46,3 +46,36 @@ eml_ns <- function(version = eml_version()) {
 
   paste0(prefix, version)
 }
+
+# Helper string used below to factor out the host from the generation of
+# schemaLocation values
+eml_host <- "https://eml.ecoinformatics.org"
+
+#' Get an appropriate `schemaLocation` value for a given version of the schema
+#'
+#' This is a simple helper to make filling in the `schemaLocation` attribute
+#' on documents this package creates.
+#'
+#' @param version Optional. Override the version of the schema.
+#' @param url Override the URL portion of the `schemaLocation` value.
+#'
+#' @return Returns a string suitable as a value for `schemaLocation`.
+#' @examples
+#' \dontrun{
+#' # Get an appropriate schemaLocation value for the current version fo EML
+#' eml_schema_location()
+#'
+#' # Get an appropriate value for EML 2.1.1
+#' eml_schema_location("eml-2.1.1")
+#'
+#' # Set `schemaLocation` to a custom URL of your choosing
+#' eml_schema_location(url = "https://example.org/eml.xsd")
+#' }
+eml_schema_location <- function(version = eml_version(), url = NULL) {
+  # Fill in a default value if `url` is not set
+  if (is.null(url)) {
+    url <- paste(eml_host, version, "eml.xsd", sep = "/")
+  }
+
+  paste(eml_ns(version), url)
+}