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| <h1 class="content-header header-section1" id="pgui_datamodel_node" itemprop="headline">Node variables</h1> |
| </div></div><p>A node variable embodies a node in a tree structure. Node |
| variables were introduced to help <a href="xgui.html">the handling of |
| XML documents in the data-model</a>, but they can be used for the |
| modeling of other tree structures as well. For more information about |
| nodes from the point of view of the template language <a href="dgui_datamodel_types.html#dgui_datamodel_node">read this earlier section</a>.</p><p>A node variable has the following properties, provided by the |
| methods of <code class="inline-code">TemplateNodeModel</code> interface:</p><ul> |
| <li> |
| <p>Basic properties:</p> |
| |
| <ul> |
| <li> |
| <p><code class="inline-code">TemplateSequenceModel |
| getChildNodes()</code>: A node has sequence of children |
| (except if the node is a leaf node, in which case the method |
| return an empty sequence or null). The child nodes should be |
| node variables as well.</p> |
| </li> |
| |
| <li> |
| <p><code class="inline-code">TemplateNodeModel getParentNode()</code>: A |
| node has exactly 1 parent node, except if the node is root |
| node of the tree, in which case the method returns |
| <code class="inline-code">null</code>.</p> |
| </li> |
| </ul> |
| </li> |
| |
| <li> |
| <p>Optional properties. If a property does not make sense in |
| the concrete use case, the corresponding method should return |
| <code class="inline-code">null</code>:</p> |
| |
| <ul> |
| <li> |
| <p><code class="inline-code">String getNodeName()</code>: The node name |
| is the name of the macro, that handles the node when you use |
| <a href="ref_directive_visit.html#ref.directive.recurse"><code>recurse</code></a> |
| and <a href="ref_directive_visit.html#ref.directive.visit"><code>visit</code></a> |
| directives. Thus, if you want to use these directives with the |
| node, the node name is <em>required</em>.</p> |
| </li> |
| |
| <li> |
| <p><code class="inline-code">String getNodeType()</code>: In the case of |
| XML: <code class="inline-code">"element"</code>, <code class="inline-code">"text"</code>, |
| <code class="inline-code">"comment"</code>, ...etc. This information, if |
| available, is used by the <code class="inline-code">recurse</code> and |
| <code class="inline-code">visit</code> directives to find the default |
| handler macro for a node. Also it can be useful for other |
| application specific purposes.</p> |
| </li> |
| |
| <li> |
| <p><code class="inline-code">String getNamespaceURI()</code>: The node |
| namespace (has nothing to do with FTL namespaces used for |
| libraries) this node belongs to. For example, in the case of |
| XML, this is the URI of the XML namespace the element or |
| attribute belongs to. This information, if available, is used |
| by the <code class="inline-code">recurse</code> and <code class="inline-code">visit</code> |
| directives to find the FTL namespaces that store the handler |
| macros.</p> |
| </li> |
| </ul> |
| </li> |
| </ul><p>On the FTL side, the direct utilization of node properties is |
| done with <a href="ref_builtins_node.html">node built-ins</a>, and |
| with the <code class="inline-code">visit</code> and <code class="inline-code">recurse</code> |
| macros.</p><p>In most use cases, variables that implement |
| <code class="inline-code">TemplateNodeModel</code>, implement other interfaces as |
| well, since node variable properties just provide the basic |
| infrastructure for navigating between nodes. For a concrete example, |
| see <a href="xgui.html">how FreeMarker deals with XML</a>.</p><div class="bottom-pagers-wrapper"><div class="pagers bottom"><a class="paging-arrow previous" href="pgui_datamodel_directive.html"><span>Previous</span></a><a class="paging-arrow next" href="pgui_datamodel_objectWrapper.html"><span>Next</span></a></div></div></div></div> </div> |
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