Add support for <Form encType=text/plain>

Author: brophdawg11

packages/react-router-dom/__tests__/data-browser-router-test.tsx

@@ -3307,6 +3307,35 @@ function testDomRouter(
         expect(await request.text()).toEqual(body);
       });
 
+      it('serializes into text on <Form encType="text/plain" submissions', async () => {
+        let actionSpy = jest.fn();
+        let router = createTestRouter(
+          createRoutesFromElements(
+            <Route path="/" action={actionSpy} element={<FormPage />} />
+          ),
+          { window: getWindow("/") }
+        );
+        render(<RouterProvider router={router} />);
+
+        function FormPage() {
+          return (
+            <Form method="post" encType="text/plain">
+              <input name="a" defaultValue="1" />
+              <input name="b" defaultValue="2" />
+              <button type="submit">Submit</button>
+            </Form>
+          );
+        }
+
+        fireEvent.click(screen.getByText("Submit"));
+        expect(await actionSpy.mock.calls[0][0].request.text())
+          .toMatchInlineSnapshot(`
+          "a=1
+          b=2
+          "
+        `);
+      });
+
       it("includes submit button name/value on form submission", async () => {
         let actionSpy = jest.fn();
         let router = createTestRouter(

packages/react-router-dom/dom.ts

@@ -169,6 +169,7 @@ export interface SubmitOptions {
 const supportedFormEncTypes: Set<FormEncType> = new Set([
   "application/x-www-form-urlencoded",
   "multipart/form-data",
+  "text/plain",
 ]);
 
 function getFormEncType(encType: string | null) {
@@ -259,5 +260,11 @@ export function getFormSubmissionInfo(
     body = target;
   }
 
+  // Send body for <Form encType="text/plain" so we encode it into text
+  if (formData && encType === "text/plain") {
+    body = formData;
+    formData = undefined;
+  }
+
   return { action, method: method.toLowerCase(), encType, formData, body };
 }

packages/react-router-dom/index.tsx

@@ -666,10 +666,10 @@ export interface FormProps extends React.FormHTMLAttributes<HTMLFormElement> {
    * `<form encType>` - enhancing beyond the normal string type and limiting
    * to the built-in browser supported values
    */
-  encType?: Extract<
-    FormEncType,
-    "application/x-www-form-urlencoded" | "multipart/form-data"
-  >;
+  encType?:
+    | "application/x-www-form-urlencoded"
+    | "multipart/form-data"
+    | "text/plain";
 
   /**
    * Normal `<form action>` but supports React Router's relative paths.

packages/router/__tests__/router-test.ts

@@ -6486,6 +6486,47 @@ describe("a router", () => {
       expect(await request.text()).toEqual(body);
     });
 
+    it("serializes body as text/plain (FormData)", async () => {
+      let t = setup({
+        routes: [{ id: "root", path: "/", action: true }],
+      });
+
+      let body = new FormData();
+      body.append("a", "1");
+      body.append("b", "2");
+      let nav = await t.navigate("/", {
+        formMethod: "post",
+        formEncType: "text/plain",
+        body,
+      });
+      expect(t.router.state.navigation.text).toMatchInlineSnapshot(`
+        "a=1
+        b=2
+        "
+      `);
+      expect(t.router.state.navigation.formData).toBeUndefined();
+      expect(t.router.state.navigation.json).toBeUndefined();
+
+      await nav.actions.root.resolve("ACTION");
+
+      expect(nav.actions.root.stub).toHaveBeenCalledWith({
+        params: {},
+        request: expect.any(Request),
+      });
+
+      let request = nav.actions.root.stub.mock.calls[0][0].request;
+      expect(request.method).toBe("POST");
+      expect(request.url).toBe("http://localhost/");
+      expect(request.headers.get("Content-Type")).toBe(
+        "text/plain;charset=UTF-8"
+      );
+      expect(await request.text()).toMatchInlineSnapshot(`
+        "a=1
+        b=2
+        "
+      `);
+    });
+
     it("serializes body as FormData when encType=undefined", async () => {
       let t = setup({
         routes: [{ id: "root", path: "/", action: true }],

packages/router/router.ts

@@ -3095,7 +3095,6 @@ function normalizeNavigateOptions(
   }
 
   // Create a Submission on non-GET navigations
-  let submission: Submission;
   let rawFormMethod = opts.formMethod || "get";
   let formMethod = normalizeFormMethod
     ? (rawFormMethod.toUpperCase() as V7_FormMethod)
@@ -3104,39 +3103,45 @@ function normalizeNavigateOptions(
 
   if (opts.body) {
     if (opts.formEncType === "text/plain") {
-      submission = {
-        formMethod,
-        formAction,
-        formEncType: opts.formEncType,
-        text:
-          typeof opts.body === "string" ? opts.body : JSON.stringify(opts.body),
-        formData: undefined,
-        json: undefined,
-      };
+      let text =
+        typeof opts.body === "string"
+          ? opts.body
+          : opts.body instanceof FormData ||
+            opts.body instanceof URLSearchParams
+          ? // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#plain-text-form-data
+            Array.from(opts.body.entries()).reduce(
+              (acc, [name, value]) => `${acc}${name}=${value}\n`,
+              ""
+            )
+          : String(opts.body);
 
-      return { path, submission };
+      return {
+        path,
+        submission: {
+          formMethod,
+          formAction,
+          formEncType: opts.formEncType,
+          text,
+          formData: undefined,
+          json: undefined,
+        },
+      };
     } else if (opts.formEncType === "application/json") {
       try {
-        if (typeof opts.body === "string") {
-          submission = {
-            formMethod,
-            formAction,
-            formEncType: opts.formEncType,
-            text: undefined,
-            formData: undefined,
-            json: JSON.parse(opts.body),
-          };
-        } else {
-          submission = {
+        let json =
+          typeof opts.body === "string" ? JSON.parse(opts.body) : opts.body;
+
+        return {
+          path,
+          submission: {
             formMethod,
             formAction,
             formEncType: opts.formEncType,
             text: undefined,
             formData: undefined,
-            json: opts.body,
-          };
-        }
-        return { path, submission };
+            json,
+          },
+        };
       } catch (e) {
         return {
           path,
@@ -3178,7 +3183,7 @@ function normalizeNavigateOptions(
     }
   }
 
-  submission = {
+  let submission: Submission = {
     formMethod,
     formAction,
     formEncType: