gistfile1.diff

diff --git a/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php b/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
index 2cad8a4..51c4924 100644
--- a/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
+++ b/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
@@ -127,6 +127,16 @@ class XmlExporter extends AbstractExporter
             }
         }
 
+        foreach ($metadata->associationMappings as $name => $field) {
+            if (isset($field['id']) && $field['id']) {
+                $id[$name] = $field;
+                $id[$name]['associationKey'] = true;
+                $id[$name]['type'] = 'string';
+
+//                var_dump($field); die();
+            }
+        }
+
         if ( ! $metadata->isIdentifierComposite && $idGeneratorType = $this->_getIdGeneratorTypeString($metadata->generatorType)) {
             $id[$metadata->getSingleIdentifierFieldName()]['generator']['strategy'] = $idGeneratorType;
         }
@@ -163,6 +173,11 @@ class XmlExporter extends AbstractExporter
                 if (isset($field['precision'])) {
                     $fieldXml->addAttribute('precision', $field['precision']);
                 }
+
+                if (isset($field['nullable'])) {
+                    $fieldXml->addAttribute('nullable', $field['nullable']  === true ? 'true' : 'false');
+                }
+
                 if (isset($field['scale'])) {
                     $fieldXml->addAttribute('scale', $field['scale']);
                 }