# OpenLink Virtuoso Universal Server: Documentation - tree

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Virtuoso Functions Guide

## tree

A container for displaying a tree of nested nodes.
< tree name (required) annotation (optional) initial-enable (optional) enabled (optional) instantiate (optional) control-udt (optional) xsd-stub-xhtml (optional) width (optional) height (optional) show-root (optional) multi-branch (required) orientation (required) root (required) child-function (required) start-path (required) open-at (optional) debug-srcfile (optional) debug-srcline (optional) debug-log (optional) />
Description

This can be used for hierarchical tables of contents, directory browsing, hierarchical menus and such. The tree can have either one or more branches open at any time, up to the leaves. The tree has a root, which may or may not be visible. The contents of the tree can either be fixed, in which case these are an XML tree, or dynamic, in which case these are generated level by level by SQL functions attached to the tree. The tree can have various external appearences.

The tree is represented at run time by a vspx_tree instance. Nodes of the tree are represented by vspx_tree_node objects, which are childs of the vspx_tree. The nodes hold an identifier (vc_instance_name) of the corresponding tree branch, which is used to retrieve children of the node. These also hold a flag (tn_open member) indicating if the node is open or not.

Attributes
name = SqlName

A page level unique name identifying a control.

annotation

A human readable comment.

initial-enable = CalculateableValue

Determines whether a control is initially visible. True by default. Could be data-bound to an SQL expression.

enabled = CalculateableValue

Determines whether a control is visible. True by default. Could be data-bound to an SQL expression.

instantiate = CalculateableValue

Determines whether a control instantiate its children. It is true by default. It could be data-bound to an SQL expression. Unlike most of calcucateable attributes, the value of this attribute for a control is calcluated before calling 'on-init' event handler of the control; other values are calculated before calling 'before-data-bind' event handler.

control-udt = SqlName

At run time every control is represented as an instance of some user-defined type (UDT). VSPX compiles selects the UDT to use depending on name of the XML element that represents the control and maybe some of its attributes. In some specific cases the application developer may instruct VSPX compiler to use some other UDT, e.g. an application-specific UDT that is derived from the preset one. If specified, the value of 'control-udt' attribute should be equal to the name of the desired target UDT.

xsd-stub-xhtml

This attribute is for internal use only. It has no effect if added to the source VSPX file.

width

Visible width of the control when it is displayed in WYSIWYG tools when the source VSPX text is edited. The value of this attribute will not be used when the resulting HTML is rendered.

height

Visible width of the control when it is displayed in WYSIWYG tools when the source VSPX text is edited. The value of this attribute will not be used when the resulting HTML is rendered.

show-root

This attribute is obsolete and has no effect.

multi-branch

This determines whether more than one branches can be open at one time. The values are 0 and 1 (true and false). The default is 0 (false).

orientation

This can be 'horizontal' or 'vertical', the default is 'vertical'. The tree can have different styles. The default is a vertical arrangement with open levels indented, the children under the parent node. Each node template is a single line. The horizontal style shows each level on a separate line. In this case it is not allowed multiple open branches. The children of the root will be shown on one line. When one is opened, its children will fill the next line.

root = SqlName

This is a SQL expression which produces the root object. This can be of any data type, a file system path is an example.

    create procedure root_node (in path varchar)
    {
      declare i, l int;
      declare ret, arr any;
      arr :=
        vector_concat (sys_dirlist (path, 0), sys_dirlist (path, 1));

      return arr;
    };

child-function = SqlName

Given the result of the root expression, this must generate an array of similar elements corresponing to the children of the node in question. This same function should be applicable to each element of the array it returns. If the array is empty then the node in question is a leaf.

    -- Example of this function

    create procedure child_node (in node_name varchar, in node varchar)
    {
      declare i, l int;
      declare ret, arr any;
      declare exit handler for sqlstate '*'
        {
          return vector ();
        };
      if (isstring (file_stat (node_name, 3)))
        return vector ();

      arr :=
        vector_concat (sys_dirlist (node_name, 0), sys_dirlist (node_name, 1));

      return arr;
    }
    ;

start-path = CalculateableValue

This is an expression which will be evaluated and passed to the 'root' function as argument.

open-at = CalculateableValue

This is an expression which will be used as XPath expression to designate which branches of the tree are open and which are not initially.

debug-srcfile

URI of the source document where the tag comes from.

debug-srcline

Line number in the source document where the tag comes from.

debug-log

This defines what sort of data are saved to the debugging log.

Declaration of type vspx_tree

    create type vspx_tree under vspx_control
    as
      (
        vt_current_node int default -1,
        vt_node any default null,
        vt_open_at varchar default null,
        vt_xpath_id varchar default null
      )
    temporary self as ref
    overriding method vc_view_state (stream any, n int) returns any,
    method vc_get_state () returns any,
    method vc_open_at (path varchar) returns any,
    constructor method vspx_tree (name varchar, parent vspx_control)

Examples

<?xml version="1.0"?> <!-- - - $Id: tree__0.vspx,v 1.2 2006/08/16 00:04:15 source Exp $ - - This file is part of the OpenLink Software Virtuoso Open-Source (VOS) - project. - - Copyright (C) 1998-2006 OpenLink Software - - This project is free software; you can redistribute it and/or modify it - under the terms of the GNU General Public License as published by the - Free Software Foundation; only version 2 of the License, dated June 1991. - - This program is distributed in the hope that it will be useful, but - WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - General Public License for more details. - - You should have received a copy of the GNU General Public License along - with this program; if not, write to the Free Software Foundation, Inc., - 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA - -

    <v:page name="demo_tree" xmlns:v="http://www.openlinksw.com/vspx/">
    <html>
     <body>
     <v:form name="f1" method="POST" type="simple">
     <div>
     <v:tree name="tree1" multi-branch="1" orientation="vertical"
             root="root_node" start-path="." child-function="child_node" >
      <v:node-template name="node_tmpl">
        <div STYLE="margin-left:1em;">
    	<v:button name="tree1_toggle" action="simple" style="image" value="--case (control.vc_parent as vspx_tree_node).tn_open when 0 then 'plus.gif' else 'minus.gif' end" />
    	<b><v:label name="label1" value="--(control.vc_parent as vspx_tree_node).tn_value" /></b>
    	<v:node />
        </div>
      </v:node-template>
      <v:leaf-template name="leaf_tmpl">
        <div STYLE="margin-left:1em;">
    	<v:label name="label2" value="--(control.vc_parent as vspx_tree_node).tn_value" />
        </div>
      </v:leaf-template>
     </v:tree>
     </div>
     </v:form>
     </body>
    </html>
    </v:page>

See Also: Reference Material in the Tutorial:

VX-S-4