Allow modules to alter information about fields that should be prepopulated in log forms.

modules/farm/farm_log/farm_log.api.php

@@ -79,6 +79,27 @@ function hook_farm_log_prepopulate_reference_fields($log_type) {
   );
 }
 
+/**
+ * Allow modules to alter information about fields that should be
+ * prepopulated in log forms.
+ *
+ * @param array $fields
+ *   An array of field information defined via
+ *   hook_farm_log_prepopulate_reference_fields().
+ * @param string $log_type
+ *   The log type.
+ *
+ * @return array
+ *   Returns an array of field information.
+ */
+function hook_farm_log_prepopulate_reference_fields_alter(&$fields, $log_type) {
+
+  // Example: don't allow prepopulating the asset field on activity logs.
+  if ($log_type == 'farm_activity') {
+    unset($fields['field_farm_asset']);
+  }
+}
+
 /**
  * @}
  */

modules/farm/farm_log/farm_log.module

@@ -369,6 +369,9 @@ function farm_log_prepopulate_log_form_references(&$form) {
   // this log type.
   $fields = module_invoke_all('farm_log_prepopulate_reference_fields', $log_type);
 
+  // Allow modules to alter the field information.
+  drupal_alter('farm_log_prepopulate_reference_fields', $fields, $log_type);
+
   // Populate the fields.
   foreach ($fields as $field => $info) {