From a6fe71da3a351210ee21e45ef5014e2edf2ccb60 Mon Sep 17 00:00:00 2001
From: Sean Doyle <sean.p.doyle24@gmail.com>
Date: Sun, 7 Feb 2021 15:03:51 -0500
Subject: [PATCH] Prepare Frame Form Submission fetch headers

Closes https://github.com/hotwired/turbo/issues/86
Closes https://github.com/hotwired/turbo/pull/110

When submitting a Form that is within a `<turbo-frame>` or targets a
`<turbo-frame>`, ensure that the `Turbo-Frame` header is present.

Since the constructive-style
`FetchRequestDelegate.additionalHeadersForRequest()` was replaced by the
mutative style `FetchRequestDelegate.prepareHeadersForRequest()`, this
commit changes the `FetchRequest.headers` property to be `readonly` and
created at constructor-time so that its values can be mutated prior to
the request's submission.

Testing adds listeners for `turbo:before-fetch-request` and
`turbo:before-fetch-response` so that the event logs can drain.

Co-authored-by: tleish <tleish@users.noreply.github.com>
---
 src/core/frames/frame_controller.ts           |  2 ++
 src/http/fetch_request.ts                     | 20 ++++++++-----------
 src/tests/fixtures/test.js                    |  5 +++--
 src/tests/functional/form_submission_tests.ts | 16 +++++++++++++++
 4 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/core/frames/frame_controller.ts b/src/core/frames/frame_controller.ts
index d0d507518..bc7079116 100644
--- a/src/core/frames/frame_controller.ts
+++ b/src/core/frames/frame_controller.ts
@@ -118,6 +118,8 @@ export class FrameController implements AppearanceObserverDelegate, FetchRequest
     if (this.formSubmission.fetchRequest.isIdempotent) {
       this.navigateFrame(element, this.formSubmission.fetchRequest.url.href)
     } else {
+      const { fetchRequest } = this.formSubmission
+      this.prepareHeadersForRequest(fetchRequest.headers, fetchRequest)
       this.formSubmission.start()
     }
   }
diff --git a/src/http/fetch_request.ts b/src/http/fetch_request.ts
index b5cbd4d6a..532ea3e08 100644
--- a/src/http/fetch_request.ts
+++ b/src/http/fetch_request.ts
@@ -42,6 +42,7 @@ export interface FetchRequestOptions {
 export class FetchRequest {
   readonly delegate: FetchRequestDelegate
   readonly method: FetchMethod
+  readonly headers: FetchRequestHeaders
   readonly url: URL
   readonly body?: FetchRequestBody
   readonly abortController = new AbortController
@@ -55,6 +56,7 @@ export class FetchRequest {
       this.body = body
       this.url = location
     }
+    this.headers = prepareHeadersForRequest(this)
   }
 
   get location(): URL {
@@ -116,23 +118,17 @@ export class FetchRequest {
     return this.method == FetchMethod.get
   }
 
-  get headers() {
-    const headers = { ...this.defaultHeaders }
-    if (typeof this.delegate.prepareHeadersForRequest == "function") {
-      this.delegate.prepareHeadersForRequest(headers, this)
-    }
-    return headers
-  }
-
   get abortSignal() {
     return this.abortController.signal
   }
+}
 
-  get defaultHeaders() {
-    return {
-      "Accept": "text/html, application/xhtml+xml"
-    }
+function prepareHeadersForRequest(fetchRequest: FetchRequest) {
+  const headers = { "Accept": "text/html, application/xhtml+xml" }
+  if (typeof fetchRequest.delegate.prepareHeadersForRequest == "function") {
+    fetchRequest.delegate.prepareHeadersForRequest(headers, fetchRequest)
   }
+  return headers
 }
 
 function mergeFormDataEntries(url: URL, entries: [string, FormDataEntryValue][]): URL {
diff --git a/src/tests/fixtures/test.js b/src/tests/fixtures/test.js
index 0cfff6493..9d5fef0eb 100644
--- a/src/tests/fixtures/test.js
+++ b/src/tests/fixtures/test.js
@@ -16,6 +16,7 @@
   "turbo:before-visit",
   "turbo:load",
   "turbo:render",
-  "turbo:request-end",
-  "turbo:visit"
+  "turbo:visit",
+  "turbo:before-fetch-request",
+  "turbo:before-fetch-response",
 ])
diff --git a/src/tests/functional/form_submission_tests.ts b/src/tests/functional/form_submission_tests.ts
index fe90a07cb..b1adb20e0 100644
--- a/src/tests/functional/form_submission_tests.ts
+++ b/src/tests/functional/form_submission_tests.ts
@@ -183,6 +183,14 @@ export class FormSubmissionTests extends TurboDriveTestCase {
     this.assert.equal(htmlAfter, htmlBefore)
   }
 
+  async "test frame form submission within a frame submits the Turbo-Frame header"() {
+    await this.clickSelector("#frame form.redirect input[type=submit]")
+
+    const { fetchOptions } = await this.nextEventNamed("turbo:before-fetch-request")
+
+    this.assert.ok(fetchOptions.headers["Turbo-Frame"], "submits with the Turbo-Frame header")
+  }
+
   async "test invalid frame form submission with unprocessable entity status"() {
     await this.clickSelector("#frame form.unprocessable_entity input[type=submit]")
     await this.nextBeat
@@ -260,6 +268,14 @@ export class FormSubmissionTests extends TurboDriveTestCase {
     this.assert.equal(await this.pathname, "/src/tests/fixtures/one.html")
   }
 
+  async "test form submission targeting a frame submits the Turbo-Frame header"() {
+    await this.clickSelector('#targets-frame [type="submit"]')
+
+    const { fetchOptions } = await this.nextEventNamed("turbo:before-fetch-request")
+
+    this.assert.ok(fetchOptions.headers["Turbo-Frame"], "submits with the Turbo-Frame header")
+  }
+
   get formSubmitted(): Promise<boolean> {
     return this.hasSelector("html[data-form-submitted]")
   }