Pass original URL to curl_modify_url() to preserve original encoding (#788)

Author: jeroen

NEWS.md

@@ -1,5 +1,8 @@
 # httr2 (development version)
 
+* Refactor `url_modify()` to better retain exact formatting of URL components 
+  that are not modified. (#788)
+
 # httr2 1.2.1
 
 * Colons in paths are no longer escaped.

R/url.R

@@ -95,9 +95,6 @@ url_modify <- function(
     stop_input_type(url, "a string or parsed URL")
   }
   string_url <- is_string(url)
-  if (string_url) {
-    url <- url_parse(url)
-  }
 
   check_url_component(scheme)
   check_url_component(hostname)
@@ -130,11 +127,12 @@ url_modify <- function(
     fragment = fragment
   )
   new <- new[!map_lgl(new, leave_as_is)]
-  url[names(new)] <- new
 
   if (string_url) {
-    url_build(url)
+    new[map_lgl(new, is.null)] <- ""
+    url_build(structure(c(url = url, new), class = "httr2_url"))
   } else {
+    url[names(new)] <- new
     url
   }
 }
@@ -262,13 +260,16 @@ url_build <- function(url) {
     stop_input_type(url, "a parsed URL")
   }
 
-  if (length(url$query) == 0) {
+  if (is.null(url$query)) {
+    query <- NULL
+  } else if (length(url$query) == 0 || identical(url$query, "")) {
     query <- ""
   } else {
     query <- I(url_query_build(url$query))
   }
 
   url <- curl::curl_modify_url(
+    url = url$url,
     scheme = url$scheme,
     host = url$hostname,
     user = url$username,

tests/testthat/test-url.R

@@ -127,6 +127,12 @@ test_that("path always starts with /", {
   expect_equal(url_modify("https://x.com/abc", path = NULL), "https://x.com/")
 })
 
+test_that("only modifies specified components", {
+  url <- "http://x.com/a%2Fb/"
+  expect_equal(url_modify(url), url)
+  expect_equal(url_modify(url, query = list(x=1)), "http://x.com/a%2Fb/?x=1")
+})
+
 # relative url ------------------------------------------------------------
 
 test_that("can set relative urls", {