fix: Add custom payload template support for form submission webhooks (#25719)

* fix: Add custom payload template support for form submission webhooks

* delete

* Update applyTemplate function signature

Refactor applyTemplate function to accept specific data type.

packages/features/webhooks/lib/sendPayload.ts

@@ -173,7 +173,11 @@ function getZapierPayload(data: WithUTCOffsetType<EventPayloadType & { createdAt
   return JSON.stringify(body);
 }
 
-function applyTemplate(template: string, data: WebhookDataType, contentType: ContentType) {
+function applyTemplate(
+  template: string,
+  data: WebhookDataType | Record<string, unknown>,
+  contentType: ContentType
+) {
   const compiled = compile(template)(data).replace(/&quot;/g, '"');
 
   if (contentType === "application/json") {
@@ -268,15 +272,27 @@ export const sendGenericWebhookPayload = async ({
   data: Record<string, unknown>;
   rootData?: Record<string, unknown>;
 }) => {
-  const body = JSON.stringify({
+  const { payloadTemplate: template } = webhook;
+
+  const contentType =
+    !template || jsonParse(template) ? "application/json" : "application/x-www-form-urlencoded";
+
+  const defaultPayload = {
     // Added rootData props first so that using the known(i.e. triggerEvent, createdAt, payload) properties in rootData doesn't override the known properties
     ...rootData,
     triggerEvent: triggerEvent,
     createdAt: createdAt,
     payload: data,
-  });
+  };
 
-  return _sendPayload(secretKey, webhook, body, "application/json");
+  let body: string;
+  if (template) {
+    body = applyTemplate(template, defaultPayload, contentType);
+  } else {
+    body = JSON.stringify(defaultPayload);
+  }
+
+  return _sendPayload(secretKey, webhook, body, contentType);
 };
 
 export const createWebhookSignature = (params: { secret?: string | null; body: string }) =>