Resolve #3369994 "Subscription doesnt accept"

Closes #3369994.

Before values are passed to Sendgrid's request body, we do some checking on the field type. If it's a number, we cast it to either an int or float; otherwise we just pass it through as a string.

We don't know what formats are wanted for Date fields, but we could add this as well.

src/Plugin/WebformHandler/WebformSendGridHandler.php

@@ -293,19 +293,32 @@ class WebformSendGridHandler extends WebformHandlerBase {
     // Email is a required field already set by $email parameter.
     unset($reservedFields['email']);
 
+    ['reserved' => $reserved, 'custom' => $custom] = $this->getFieldDefinitions();
+
     $requestBody = new \stdClass();
     $requestBody->list_ids = [$listId];
     $contact = new \stdClass();
+
     // Reserved fields.
     $contact->email = $email;
     foreach ($reservedFields as $fieldName => $value) {
-      $contact->{$fieldName} = $value;
+      $candidates = array_filter($reserved, function ($f) use ($fieldName) {
+        return $f['name'] === $fieldName;
+      });
+      $field_def = reset($candidates);
+      $contact->{$fieldName} = $this->castField($value, $field_def);
     }
+
     // Custom fields.
     $contact->custom_fields = new \stdClass();
     foreach ($customFields as $fieldName => $value) {
-      $contact->custom_fields->{$fieldName} = $value;
+      $candidates = array_filter($custom, function ($f) use ($fieldName) {
+        return $f['id'] === $fieldName;
+      });
+      $field_def = reset($candidates);
+      $contact->custom_fields->{$fieldName} = $this->castField($value, $field_def);
     }
+
     $requestBody->contacts = [$contact];
 
     // @see https://sendgrid.api-docs.io/v3.0/contacts/add-or-update-a-contact
@@ -314,4 +327,31 @@ class WebformSendGridHandler extends WebformHandlerBase {
     return $response->statusCode() === 202;
   }
 
+  /**
+   * Cast tokenised value to appropriate type prior to sending to Sendgrid.
+   *
+   * @param mixed $value
+   *   The raw value, probably a string representing a tokenised value.
+   * @param array $field_def
+   *   The field definition, will contain a key `field_type`.
+   *
+   * @return mixed
+   *   The field cast to its appropriate type.
+   */
+  protected function castField($value, array $field_def = []) {
+    ['field_type' => $field_type] = $field_def;
+
+    switch ($field_type) {
+      case 'Number':
+        if (strpos('.', $value) !== FALSE) {
+          return floatval($value);
+        }
+        return intval($value);
+
+      // @TODO send valid date value for field type
+      default:
+        return $value;
+    }
+  }
+
 }