如何仅返回SOLR中字段的截断部分？

<requestHandler name="/select" class="solr.SearchHandler">
  <lst name="defaults">
    <str name="defType">edismax</str>
    <str name="qf">your_field</str>
    <str name="fl">your_field, your_truncated_field:[sub(0,10)]</str> <!-- your_truncated_field是截断后的字段 -->
    <str name="group">true</str>
    <str name="group.field">your_field</str> <!-- 按照该字段进行分组 -->
    <str name="group.limit">1</str> <!-- 每个分组返回的文档数量 -->
  </lst>
</requestHandler>

/select?q=your_query&fq={!collapse field=your_field}&fl=your_field, your_truncated_field