Respect Rails action toJSON bodies

Author: justin808

packages/react-on-rails/src/railsAction.ts

@@ -147,7 +147,7 @@ const warnOnImplicitBodyWithDynamicPath = (): void => {
   );
 };
 
-const nonJsonBodyTypeName = (requestBody: unknown, seenObjects = new WeakSet()): string | null => {
+const nonJsonBodyTypeName = (requestBody: unknown): string | null => {
   if (requestBody === undefined) {
     return 'undefined';
   }
@@ -197,21 +197,6 @@ const nonJsonBodyTypeName = (requestBody: unknown, seenObjects = new WeakSet()):
     return 'Promise';
   }
 
-  if (seenObjects.has(requestBody)) {
-    return null;
-  }
-  seenObjects.add(requestBody);
-
-  const nestedValues = Array.isArray(requestBody)
-    ? requestBody
-    : Object.values(requestBody as Record<string, unknown>);
-  for (const nestedValue of nestedValues) {
-    const nestedTypeName = nonJsonBodyTypeName(nestedValue, seenObjects);
-    if (nestedTypeName !== null) {
-      return nestedTypeName;
-    }
-  }
-
   return null;
 };
 
@@ -221,19 +206,6 @@ const jsonBodyTypeError = (bodyTypeName: string): TypeError =>
       'Return a plain JSON value, null, or undefined instead.',
   );
 
-const assertJsonBodyValue = (requestBody: unknown, hasJsonBody: boolean): void => {
-  if (!hasJsonBody) {
-    return;
-  }
-
-  const bodyTypeName = nonJsonBodyTypeName(requestBody);
-  if (bodyTypeName === null) {
-    return;
-  }
-
-  throw jsonBodyTypeError(bodyTypeName);
-};
-
 const stringifyJsonBody = (requestBody: unknown): string => {
   try {
     const serializedBody = JSON.stringify(requestBody, (_key, value: unknown) => {
@@ -386,7 +358,7 @@ export function createRailsAction<TVariables = undefined, TResponse = unknown>(
     const shouldWarnOnDiscardedDeleteBody =
       !warnedOnDiscardedDeleteBody && requestBody !== undefined && requestBody !== null;
     const shouldWarnOnImplicitDynamicPathBody = !warnedOnImplicitDynamicPathBody && hasJsonBody;
-    assertJsonBodyValue(requestBody, hasJsonBody);
+    const serializedRequestBody = hasJsonBody ? stringifyJsonBody(requestBody) : undefined;
     if (shouldWarnOnDiscardedDeleteBody) {
       warnOnDiscardedDeleteBody(requestBody);
       warnedOnDiscardedDeleteBody = true;
@@ -409,7 +381,7 @@ export function createRailsAction<TVariables = undefined, TResponse = unknown>(
           resolveHeaders(options.headers, typedVariables),
           callOptionsValue(callOptions, 'headers'),
         ),
-        body: hasJsonBody ? stringifyJsonBody(requestBody) : undefined,
+        body: serializedRequestBody,
       });
     } catch (fetchError) {
       warnOnPossibleRedirectFetchError(fetchError);

packages/react-on-rails/tests/railsAction.test.ts

@@ -662,10 +662,32 @@ describe('createRailsAction', () => {
       body: ({ id }) => ({ project: { id } }),
     });
 
-    await expect(createProject({ id: BigInt(1) })).rejects.toThrow(/resolved to BigInt/);
+    await expect(createProject({ id: BigInt(1) })).rejects.toThrow(/contains a BigInt value/);
     expect(fetchMock).not.toHaveBeenCalled();
   });
 
+  it('serializes custom toJSON values without inspecting internal non-JSON state', async () => {
+    class Money {
+      raw = new Map([['internal', true]]);
+
+      constructor(private readonly cents: number) {}
+
+      toJSON(): number {
+        return this.cents / 100;
+      }
+    }
+
+    const createProject = createRailsAction<undefined, { ok: true }>({
+      path: '/api/projects',
+      body: () => ({ project: { budget: new Money(1234) } }),
+    });
+
+    await expect(createProject()).resolves.toEqual({ project: { id: 1 } });
+
+    const [, init] = fetchMock.mock.calls[0];
+    expect(init.body).toBe(JSON.stringify({ project: { budget: 12.34 } }));
+  });
+
   it('rejects non-JSON values returned from custom toJSON methods before fetch', async () => {
     const customJsonValue = (jsonValue: unknown): { toJSON: () => unknown } => {
       const value = {};