PHPCMS V9 adds secondary navigation

I looked at phpcms today and found a problem when writing the secondary navigation. When querying the navigation bar information, the $r[arrchildid] returned was not consistent with what I imagined. The document said that the sub-column id was returned, but it was somewhat different.

Starting idea:

    首页       {pc:content action="category" catid="0" num="10" siteid="$siteid" order="listorder ASC"}
          {loop $data $r}
          {if $r[arrchildid]}
                          {$r[catname]}                                   {pc:content action="category" catid="$r[catid]" num="10" siteid="$siteid" order="listorder ASC" return="data2"}
                    {loop $data2 $v}
                      {$v[catname]}                    {/loop}
                  {/pc}
                   
                      {/if}
        {/loop}
     {/pc}

General idea: Check whether there is a sub-column ID under the document, and if so, output the secondary navigation. Line 5 of the code is to detect whether there is a sub-column ID under the column, but I found that when there is no sub-column, the ID of the current column will be returned, causing the judgment to fail to achieve the expected effect, so I changed my mind and the code is as follows:

    首页      {pc:content action="category" catid="0" num="10" siteid="$siteid" order="listorder ASC"}
         {loop $data $r}
           {if $r[arrchildid] != $r[catid]}
                            {$r[catname]}                                     {pc:content action="category" catid="$r[catid]" num="10" siteid="$siteid" order="listorder ASC" return="data2"}
                      {loop $data2 $v}
                        {$v[catname]}                      {/loop}
                     {/pc}
                    
                         {else}
              {$r[catname]}           {/if}
        {/loop}
      {/pc}

Judgement acquisition Whether the sub-column id is equal to the column id, if equal, it means there is no sub-column, if not equal, it means there is a sub-column and the sub-column is displayed