Add AJAX support for form submissions

.gitignore

@@ -12,3 +12,6 @@ assets/components/formit/tmp
 _packages/*.*
 !_packages/.gitignore
 !_packages/*.zip
+
+_build/gpm_resolvers/
+_build/gpm_scripts/

_build/gpm.yml

@@ -43,6 +43,9 @@ systemSettings:
   - key: max_chars_textfield
     area: formit
     value: 125
+  - key: frontend_js
+    value: 'js/web/formit.js'
+    area: formit
 
 chunks:
   - name: fiDefaultEmailTpl

assets/components/formit/action.php

@@ -0,0 +1,108 @@
+<?php
+/**
+ * FormIt AJAX Endpoint
+ *
+ * Handles AJAX form submissions via MODX_API_MODE.
+ * Retrieves snippet configuration from session/cache by ajaxToken,
+ * processes the form through FormIt, and returns JSON response.
+ *
+ * @package formit
+ */
+
+use MODX\Revolution\modResource;
+use Sterc\FormIt;
+
+/* Reject non-AJAX requests */
+if (empty($_SERVER['HTTP_X_REQUESTED_WITH']) || strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) !== 'xmlhttprequest') {
+    header('Location: /');
+    exit;
+}
+
+/* Boot MODX in API mode */
+define('MODX_API_MODE', true);
+require_once dirname(__DIR__, 3) . '/config.core.php';
+require_once MODX_CORE_PATH . 'config/' . MODX_CONFIG_KEY . '.inc.php';
+require_once MODX_BASE_PATH . 'index.php';
+
+$modx->lexicon->load('formit:default');
+header('Content-Type: application/json; charset=UTF-8');
+
+/* Validate ajaxToken */
+$ajaxToken = $_POST['ajaxToken'] ?? '';
+if (!preg_match('/^[a-f0-9]{32}$/', $ajaxToken)) {
+    http_response_code(400);
+    echo json_encode([
+        'success' => false,
+        'message' => $modx->lexicon('formit.err_config_ns')
+    ]);
+    exit;
+}
+
+/* Retrieve stored config: session first, then cache fallback */
+$config = $_SESSION['formit'][$ajaxToken] ?? null;
+if (empty($config)) {
+    $config = $modx->cacheManager->get('formit/props_' . $ajaxToken);
+}
+
+if (empty($config) || !is_array($config)) {
+    http_response_code(400);
+    echo json_encode([
+        'success' => false,
+        'message' => $modx->lexicon('formit.err_config_expired')
+    ]);
+    exit;
+}
+
+/* Set up resource context from stored pageId */
+$pageId = (int) ($config['pageId'] ?? 0);
+if ($pageId && $resource = $modx->getObject(modResource::class, $pageId)) {
+    $modx->switchContext($resource->get('context_key'));
+    $modx->resource = $resource;
+}
+
+/* Parser is not auto-initialized in API mode, but required by hooks that process chunks */
+$modx->getParser();
+
+/* Run FormIt — same flow as snippet.formit.php */
+$fi = new FormIt($modx, $config);
+$fi->returnOutput = true;
+
+$fi->initialize($modx->context->get('key'));
+$fi->loadRequest();
+
+$fields = $fi->request->prepare();
+$output = $fi->request->handle($fields);
+
+/* Build JSON response */
+$response = ['success' => true];
+
+if ($fi->hasErrors()) {
+    $response['success'] = false;
+    $response['errors']  = $fi->getErrors();
+}
+
+if ($fi->postHooks) {
+    $url = $fi->postHooks->getRedirectUrl();
+    if (!empty($url)) {
+        $response['redirect_url'] = $url;
+    }
+}
+
+/* Collect all placeholders for AJAX response */
+$prefix    = $fi->config['placeholderPrefix'];
+$prefixLen = strlen($prefix);
+
+$placeholders = [];
+foreach ($modx->placeholders as $key => $value) {
+    if (strpos($key, $prefix) === 0) {
+        /* Remove prefix for response */
+        $placeholders[substr($key, $prefixLen)] = $value;
+    }
+}
+$response['placeholders'] = $placeholders;
+
+if (ob_get_level() > 0) {
+    ob_clean();
+}
+echo json_encode($response, JSON_UNESCAPED_UNICODE);
+exit;