传入函数field（myField）作为替代时，Solr 7 docfreq不返回正确的结果

Question

Solr docfreq（field，string）函数返回找到的包含传入的字符串参数的文档数。传递字符串值时，solr返回正确的结果。但是，当我传入应该使用chrg_cd_descr字段文本的函数字段（myField）时，我似乎总是将0返回为docfreq计数。

我打印出了字段（chrg_cd_descr），它确实返回了chrg_cd_descr字段的文本值。

下面是工作示例，没有工作示例

查询参数：＆q = docfreq（chrg_cd_descr，$ myterm）＆myterm = CATHETHER

{
     "chrg_cd_descr_tokens":"CATHETER",
     "chrg_cd_descr":"CATHETER",
     "spl_cd":"270272917650000",
     "id":"440fd54e-2e4e-472f-ab30-af7ae401542b",
     "_version_":1619862522425245711,
     "score":116.25723,
     "docfreq(chrg_cd_descr,$myterm)":158}
}

查询参数：＆q = docfreq（chrg_cd_descr，$ myterm）＆myterm = field（chrg_cd_descr）

{
    "chrg_cd_descr_tokens":"CATHETER",
    "chrg_cd_descr":"CATHETER",
    "spl_cd":"270272917650000",
    "id":"440fd54e-2e4e-472f-ab30-af7ae401542b",
    "_version_":1619862522425245711,
    "score":116.25723,
    "docfreq(chrg_cd_descr,$myterm)":0}
}