Parse multiple link headers (#606)

Fixes #587

Author: hadley

NEWS.md

@@ -1,5 +1,6 @@
 # httr2 (development version)
 
+* `resp_link_url()` now works if there are multiple `Link` headers (#587).
 * New `url_modify()` makes it easier to modify an existing url (#464).
 * New `req_url_relative()` for constructing relative urls (#449).
 * `url_parse()` gains `base_url` argument so you can also use it to parse relative URLs (#449).

R/resp-headers.R

@@ -173,7 +173,9 @@ resp_link_url <- function(resp, rel) {
     return()
   }
 
-  links <- parse_link(resp_header(resp, "Link"))
+  headers <- resp_headers(resp)
+  link_headers <- headers[names(headers) == "Link"]
+  links <- unlist(lapply(link_headers, parse_link), recursive = FALSE)
   sel <- map_lgl(links, ~ .$rel == rel)
   if (sum(sel) != 1L) {
     return()

tests/testthat/test-resp-headers.R

@@ -58,3 +58,12 @@ test_that("can extract specified link url", {
   expect_equal(resp_link_url(resp, "first"), NULL)
   expect_equal(resp_link_url(response(), "first"), NULL)
 })
+
+test_that("can extract from multiple link headers", {
+  resp <- response(headers = c(
+    'Link: <https://example.com/1>; rel="next"',
+    'Link: <https://example.com/2>; rel="last"'
+  ))
+  expect_equal(resp_link_url(resp, "next"), "https://example.com/1")
+  expect_equal(resp_link_url(resp, "last"), "https://example.com/2")
+})