 <p>Okey, here is the answer:</p> <pre><code>Key&lt;Invoice&gt; invoiceKey = dao.getDatastore().getKey(invoice); List&lt;Key&lt;Invoice&gt;&gt; invoiceKeyList = new ArrayList&lt;Key&lt;Invoice&gt;&gt;(); invoiceKeyList.add(invoiceKey); query.criteria(User.INVOICE_TRANSACTIONS).hasNoneOf(invoiceKeyList); </code></pre>