commit a72dc7ae50351e9a08865b55ad18ffd864552a77
Author: Christian Ehringfeld <c.ehringfeld@t-online.de>
Date:   Tue Aug 11 19:26:10 2015 +0200

    ...

diff --git a/src/validators/uniquevalidator.cpp b/src/validators/uniquevalidator.cpp
index 5c00a4c..4ef19df 100644
--- a/src/validators/uniquevalidator.cpp
+++ b/src/validators/uniquevalidator.cpp
@@ -37,7 +37,7 @@ QList<ErrorMsg> UniqueValidator::validate(QVariant value,
             e = nullptr;
             QHash<QString, QVariant> params = QHash<QString, QVariant>();
             params.insert(targetAttribute, value);
-            q.appendWhere(Expression(targetAttribute, params));
+            q.appendWhere(em->getQueryBuilder()->where(params));
             if (em->count(q) > 0) {
                 msgs.append(ErrorMsg("",
                                      "<property> \"" + value.toString() + "\" has already been taken."));