How to compose an XSL template correctly?

Question

XSL & XSLT

Hello,
I have the following structure:

1 инф группа 1
  1.1 инф группа 2
2 инф группа 3
  2.1 инф группа 4
  2.2 инф группа 5
    2.2.1 инф группа 6
3 инф группа 7

As a result, I got this XML:

<informationsystem id="31">
  <informationsystem_dir_id>0</informationsystem_dir_id>
  <structure_id>166</structure_id>
  <site_id>6</site_id>
  <name>Тестовая</name>
  <description></description>
  <items_sorting_direction>0</items_sorting_direction>
  <items_sorting_field>0</items_sorting_field>
  <groups_sorting_direction>0</groups_sorting_direction>
  <groups_sorting_field>0</groups_sorting_field>
  <image_large_max_width>300</image_large_max_width>
  <image_large_max_height>300</image_large_max_height>
  <image_small_max_width>70</image_small_max_width>
  <image_small_max_height>70</image_small_max_height>
  <siteuser_group_id>0</siteuser_group_id>
  <use_captcha>1</use_captcha>
  <watermark_file></watermark_file>
  <watermark_default_use_large_image>0</watermark_default_use_large_image>
  <watermark_default_use_small_image>0</watermark_default_use_small_image>
  <watermark_default_position_x>50%</watermark_default_position_x>
  <watermark_default_position_y>100%</watermark_default_position_y>
  <user_id>19</user_id>
  <items_on_page>10</items_on_page>
  <format_date>%d.%m.%Y</format_date>
  <format_datetime>%d.%m.%Y %H:%M:%S</format_datetime>
  <url_type>1</url_type>
  <typograph_default_items>0</typograph_default_items>
  <typograph_default_groups>0</typograph_default_groups>
  <apply_tags_automatically>1</apply_tags_automatically>
  <change_filename>1</change_filename>
  <apply_keywords_automatically>1</apply_keywords_automatically>
  <group_image_large_max_width>300</group_image_large_max_width>
  <group_image_large_max_height>300</group_image_large_max_height>
  <group_image_small_max_width>70</group_image_small_max_width>
  <group_image_small_max_height>70</group_image_small_max_height>
  <preserve_aspect_ratio>1</preserve_aspect_ratio>
  <preserve_aspect_ratio_small>1</preserve_aspect_ratio_small>
  <preserve_aspect_ratio_group>1</preserve_aspect_ratio_group>
  <preserve_aspect_ratio_group_small>1</preserve_aspect_ratio_group_small>
  <url>/for-tests/</url>
  <captcha_id>19372</captcha_id>
  <items_count>0</items_count>
  <items_total_count>0</items_total_count>
  <subgroups_count>3</subgroups_count>
  <subgroups_total_count>7</subgroups_total_count>
  <siteuser_id>0</siteuser_id>
  <group>0</group>
  <page>0</page>
  <part>0</part>
  <limit>99</limit>
  <total>0</total>
  <informationsystem_group id="16">
    <informationsystem_id>31</informationsystem_id>
    <siteuser_id>0</siteuser_id>
    <parent_id>0</parent_id>
    <top_parent_id>0</top_parent_id>
    <name>Тест 1</name>
    <description></description>
    <sorting>0</sorting>
    <path>test-1</path>
    <image_large></image_large>
    <image_small></image_small>
    <indexing>1</indexing>
    <subgroups_count>1</subgroups_count>
    <subgroups_total_count>1</subgroups_total_count>
    <items_count>0</items_count>
    <items_total_count>0</items_total_count>
    <seo_title></seo_title>
    <seo_description></seo_description>
    <seo_keywords></seo_keywords>
    <siteuser_group_id>-1</siteuser_group_id>
    <active>1</active>
    <user_id>19</user_id>
    <sns_type_id>0</sns_type_id>
    <url>/for-tests/test-1/</url>
    <dir>/upload/information_system_31/0/1/6/group_16/</dir>
    <informationsystem_group id="21">
      <informationsystem_id>31</informationsystem_id>
      <siteuser_id>0</siteuser_id>
      <parent_id>16</parent_id>
      <top_parent_id>0</top_parent_id>
      <name>Тест 2</name>
      <description></description>
      <sorting>0</sorting>
      <path>test-2</path>
      <image_large></image_large>
      <image_small></image_small>
      <indexing>1</indexing>
      <subgroups_count>0</subgroups_count>
      <subgroups_total_count>0</subgroups_total_count>
      <items_count>0</items_count>
      <items_total_count>0</items_total_count>
      <seo_title></seo_title>
      <seo_description></seo_description>
      <seo_keywords></seo_keywords>
      <siteuser_group_id>-1</siteuser_group_id>
      <active>1</active>
      <user_id>19</user_id>
      <sns_type_id>0</sns_type_id>
      <url>/for-tests/test-1/test-2/</url>
      <dir>/upload/information_system_31/0/2/1/group_21/</dir>
    </informationsystem_group>
  </informationsystem_group>
  <informationsystem_group id="26">
    <informationsystem_id>31</informationsystem_id>
    <siteuser_id>0</siteuser_id>
    <parent_id>0</parent_id>
    <top_parent_id>0</top_parent_id>
    <name>тест 3</name>
    <description></description>
    <sorting>0</sorting>
    <path>test-3</path>
    <image_large></image_large>
    <image_small></image_small>
    <indexing>1</indexing>
    <subgroups_count>3</subgroups_count>
    <subgroups_total_count>3</subgroups_total_count>
    <items_count>0</items_count>
    <items_total_count>0</items_total_count>
    <seo_title></seo_title>
    <seo_description></seo_description>
    <seo_keywords></seo_keywords>
    <siteuser_group_id>-1</siteuser_group_id>
    <active>1</active>
    <user_id>19</user_id>
    <sns_type_id>0</sns_type_id>
    <url>/for-tests/test-3/</url>
    <dir>/upload/information_system_31/0/2/6/group_26/</dir>
    <informationsystem_group id="31">
      <informationsystem_id>31</informationsystem_id>
      <siteuser_id>0</siteuser_id>
      <parent_id>26</parent_id>
      <top_parent_id>0</top_parent_id>
      <name>тест 4</name>
      <description></description>
      <sorting>0</sorting>
      <path>test-4</path>
      <image_large></image_large>
      <image_small></image_small>
      <indexing>1</indexing>
      <subgroups_count>0</subgroups_count>
      <subgroups_total_count>0</subgroups_total_count>
      <items_count>0</items_count>
      <items_total_count>0</items_total_count>
      <seo_title></seo_title>
      <seo_description></seo_description>
      <seo_keywords></seo_keywords>
      <siteuser_group_id>-1</siteuser_group_id>
      <active>1</active>
      <user_id>19</user_id>
      <sns_type_id>0</sns_type_id>
      <url>/for-tests/test-3/test-4/</url>
      <dir>/upload/information_system_31/0/3/1/group_31/</dir>
    </informationsystem_group>
    <informationsystem_group id="36">
      <informationsystem_id>31</informationsystem_id>
      <siteuser_id>0</siteuser_id>
      <parent_id>26</parent_id>
      <top_parent_id>0</top_parent_id>
      <name>тест 5</name>
      <description></description>
      <sorting>0</sorting>
      <path>test-5</path>
      <image_large></image_large>
      <image_small></image_small>
      <indexing>1</indexing>
      <subgroups_count>1</subgroups_count>
      <subgroups_total_count>1</subgroups_total_count>
      <items_count>0</items_count>
      <items_total_count>0</items_total_count>
      <seo_title></seo_title>
      <seo_description></seo_description>
      <seo_keywords></seo_keywords>
      <siteuser_group_id>-1</siteuser_group_id>
      <active>1</active>
      <user_id>19</user_id>
      <sns_type_id>0</sns_type_id>
      <url>/for-tests/test-3/test-5/</url>
      <dir>/upload/information_system_31/0/3/6/group_36/</dir>
      <informationsystem_group id="41">
        <informationsystem_id>31</informationsystem_id>
        <siteuser_id>0</siteuser_id>
        <parent_id>36</parent_id>
        <top_parent_id>0</top_parent_id>
        <name>тест 6</name>
        <description></description>
        <sorting>0</sorting>
        <path>test-6</path>
        <image_large></image_large>
        <image_small></image_small>
        <indexing>1</indexing>
        <subgroups_count>0</subgroups_count>
        <subgroups_total_count>0</subgroups_total_count>
        <items_count>0</items_count>
        <items_total_count>0</items_total_count>
        <seo_title></seo_title>
        <seo_description></seo_description>
        <seo_keywords></seo_keywords>
        <siteuser_group_id>-1</siteuser_group_id>
        <active>1</active>
        <user_id>19</user_id>
        <sns_type_id>0</sns_type_id>
        <url>/for-tests/test-3/test-5/test-6/</url>
        <dir>/upload/information_system_31/0/4/1/group_41/</dir>
      </informationsystem_group>
    </informationsystem_group>
  </informationsystem_group>
  <informationsystem_group id="46">
    <informationsystem_id>31</informationsystem_id>
    <siteuser_id>0</siteuser_id>
    <parent_id>0</parent_id>
    <top_parent_id>0</top_parent_id>
    <name>тест 7</name>
    <description></description>
    <sorting>0</sorting>
    <path>test-7</path>
    <image_large></image_large>
    <image_small></image_small>
    <indexing>1</indexing>
    <subgroups_count>0</subgroups_count>
    <subgroups_total_count>0</subgroups_total_count>
    <items_count>0</items_count>
    <items_total_count>0</items_total_count>
    <seo_title></seo_title>
    <seo_description></seo_description>
    <seo_keywords></seo_keywords>
    <siteuser_group_id>-1</siteuser_group_id>
    <active>1</active>
    <user_id>19</user_id>
    <sns_type_id>0</sns_type_id>
    <url>/for-tests/test-7/</url>
    <dir>/upload/information_system_31/0/4/6/group_46/</dir>
  </informationsystem_group>
</informationsystem>

The question is, how do I correctly compose the XSL template so that I can go over all the nested groups?
How much will be invested is not known in advance.
Each parent group has a subgroups_count field that stores the number of child subgroups.
I'm not strong in XSL, please tell me how this can be implemented.
Thank you very much in advance!

Answer 1

The question is, how do I correctly compose the XSL template so that I can go over all the nested groups?

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output indent="yes" encoding="utf-8" version="1.0"/>

  <xsl:template match="/informationsystem">
    <xsl:if test="count(informationsystem_group) &gt; 0">
      <ul>
        <xsl:apply-templates select="//informationsystem_group"/>
      </ul>
    </xsl:if>
  </xsl:template>

  <xsl:template match="informationsystem_group">
    <li>
      <xsl:value-of select="name"/>
    </li>
  </xsl:template>
</xsl:stylesheet>