Throw error when attempting to change body type (#530)

Fixes #451

NEWS.md

@@ -1,5 +1,6 @@
 # httr2 (development version)
 
+* `req_body_*()` now give informative error if you attempt to change the body type (#451).
 * `resp_body_html()` and `resp_body_xml()` now work when `req_perform()` is given a path (#448).
 * `req_body_file()` now works with files >64kb once more (#524).
 * New `req_perform_connection()` for working with streaming data. Unlike `req_perform_stream()` which uses callbacks, `req_perform_connection()` returns a regular response object with a connection as the body. It's paired with `resp_stream_bytes()`, `resp_stream_lines()`, and `resp_stream_sse()` that allows you to stream chunks as you want them. Unlike `req_perform_stream()` it supports `req_retry()` (with @jcheng5, #519).

R/req-body.R

@@ -61,7 +61,12 @@ req_body_raw <- function(req, body, type = NULL) {
     cli::cli_abort("{.arg body} must be a raw vector or string.")
   }
 
-  req_body(req, data = body, type = "raw", content_type = type %||% "")
+  req_body(
+    req,
+    data = body,
+    type = "raw",
+    content_type = type %||% ""
+  )
 }
 
 #' @export
@@ -74,7 +79,12 @@ req_body_file <- function(req, path, type = NULL) {
   }
 
   # Need to override default content-type "application/x-www-form-urlencoded"
-  req_body(req, data = new_path(path), type = "raw-file", content_type = type %||% "")
+  req_body(
+    req,
+    data = new_path(path),
+    type = "raw-file",
+    content_type = type %||% ""
+  )
 }
 
 #' @export
@@ -102,7 +112,13 @@ req_body_json <- function(req, data,
     null = null,
     ...
   )
-  req_body(req, data = data, type = "json", content_type = type, params = params)
+  req_body(
+    req,
+    data = data,
+    type = "json",
+    content_type = type,
+    params = params
+  )
 }
 
 #' @export
@@ -164,7 +180,17 @@ req_body_multipart <- function(.req, ...) {
 
 # General structure -------------------------------------------------------
 
-req_body <- function(req, data, type, content_type, params = list()) {
+req_body <- function(req, data, type, content_type, params = list(), error_call = parent.frame()) {
+  if (!is.null(req$body) && req$body$type != type) {
+    cli::cli_abort(
+      c(
+        "Can't change body type from {req$body$type} to {type}.",
+        i = "You must use only one type of `req_body_*()` per request."
+      ),
+      call = error_call
+    )
+  }
+
   req$body <- list(
     data = data,
     type = type,

tests/testthat/_snaps/req-body.md

@@ -15,3 +15,12 @@
       ! Unexpected content type "application/xml".
       * Expecting type "application/json" or suffix "json".
 
+# can't change body type
+
+    Code
+      req %>% req_body_json(list(x = 1))
+    Condition
+      Error in `req_body_json()`:
+      ! Can't change body type from raw to json.
+      i You must use only one type of `req_body_*()` per request.
+

tests/testthat/test-req-body.R

@@ -158,6 +158,9 @@ test_that("no issues with partial name matching", {
     req_body_multipart(d = "some data")
 
   expect_named(req$body$data, "d")
+})
 
-
+test_that("can't change body type", {
+  req <- request("http://example.com") %>% req_body_raw(raw(1))
+  expect_snapshot(req %>% req_body_json(list(x = 1)), error = TRUE)
 })