tree
****
Use :class:`tree` for generate html tags for tree. in fact, this command use in hierarchy data.


.. code-block:: html
   :linenos:

   <basis core="tree" nullvalue="" idcol="" parentidcol="" relationnamecol="">
      [...]
   </basis>

.. important::
   The :class:`tree` command inherit from :doc:`renderable` base class.

Attributes:
===========

nullvalue :class:`string` :class:`optional` :class:`[##-notaion`
   Determine null or empty value that determine root node on hierarchy.
   value of column :class:`parentidcol` in root record must be set to :class:`nullvalue`.
   default value for :class:`nullvalue` is :class:`0`.

idcol :class:`string` :class:`optional` :class:`[##-notaion`
   Determine column name for primary-key or principal-key in data source that use for detect parent side of hierarchy relation.
   default value for :class:`idcol` is :class:`id`.

parentidcol :class:`string` :class:`optional` :class:`[##-notaion`
   Determine column name for foreign-key in data source that use for detect child side of hierarchy relation.
   default value for :class:`parentidcol` is :class:`parentid`.

relationnamecol :class:`string` :class:`optional` :class:`[##-notaion` :class:`obsoleted`
   Determine column name in data source that use for sort hierarchy output.
   if not set, sorting is ignored.

.. note::
   For see more Information about :class:`[##-notaion`,see :doc:`../[-sharp-sharp-notation`

Example
=======

1# Create simple command
------------------------

.. code-block:: html
   :linenos:

   <basis  core="tree" datamembername="db.users" idcol="id" parentidcol="managerid" nullvalue="-1">
      
      <layout>
        <ul>
            @child
        </ul>
      </layout>

      <face level="1">
        <li>
            @lname :
            <ul>
                @child
            </ul>
        </li>
      </face>

      <face level="2">
        <li>@fname - @lname</li>
      </face>

   </basis>

.. include:: /sample-code/sample-data.rst
   :start-after: _db_users_start_
   :end-before: _db_users_end_
   
Result is:

.. code-block:: html
   :linenos:

   <ul>
        <li>
            qamsari :
            <ul>
                <li>amir - jalali</li>
                <li>akbar - karimi</li>
            </ul>
        </li>
   </ul>