XML reffers to not existing parent error of dhtml

最新推荐文章于 2024-09-04 11:23:37 发布

最新推荐文章于 2024-09-04 11:23:37 发布 · 1.6k 阅读

文章标签：

#XML #CSS #JSP #Cache #JavaScript #ViewUI

AJAX 专栏收录该内容

6 篇文章

订阅专栏

本文解决了使用 dhtmlxTree 动态加载时出现的 XML 引用不存在的父节点错误。通过确保 tree 元素的 id 属性正确指向父节点 ID，解决了这一问题。

How to solve XML reffers to not existing parent error of dhtmlxTree
When I use dhtmlxTree dynamical loading with jsp, I always get the following exception:

Error type: DataStructure
Description: XML reffers to not existing parent

The code of the jsp page is as following:
---------------------------------------------------------------------------------------------------------------
<html>
<head>
</head>
<body>
    <link rel="STYLESHEET" type="text/css" href="css/dhtmlxtree.css">
    <script src="js/dhtmlxcommon.js"></script>
    <script src="js/dhtmlxtree.js"></script>
    <div id="treeboxbox_tree" style="width:100%; height:218;background-color:#f5f5f5;border :1px solid Silver;; overflow:auto;"></div>
    <script type="text/javascript">
  tree=new dhtmlXTreeObject("treeboxbox_tree","100%","100%",0);
  tree.attachEvent("onClick",onNodeSelect);
  tree.setImagePath("images/tree/");
  tree.setXMLAutoLoading("AdminFolderServlet?action=folder_treeview");
  tree.loadXML("AdminFolderServlet?action=folder_treeview&id=1");
  function onNodeSelect(nodeId){
      document.getElementById("parent_folder_id").value = nodeId;
  }
    </script>
</body>
</html>
---------------------------------------------------------------------------------------------------------------
And the following is the code snippet used to generate XML file of the tree:
---------------------------------------------------------------------------------------------------------------
String id = request.getParameter("id");
if (id == null) id = "1";
Vector folders = Folder.getFolders(Integer.parseInt(id));
StringBuffer buff = new StringBuffer("< ?xml version=\"1.0\"?>“);
buff.append(”
“);
for (int i = 0; i < folders.size(); i++) {
Folder f = (Folder)folders.get(i);
buff.append("“);
}
buff.append(”“);
response.setContentType(”text/xml”);
response.setHeader(”Cache-Control”,”no-cache”); //HTTP 1.1
response.setHeader(”Pragma”,”no-cache”); //HTTP 1.0
response.setDateHeader(”Expires”, 0); //prevents caching at the proxy server
response.getWriter().write(buff.toString());

---------------------------------------------------------------------------------------------------------------
The generated XML is well formed.
---------------------------------------------------------------------------------------------------------------
<?xml version="1.0"?>
<tree id='1'>
<item child='1' id='2' text='Games' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
<item child='1' id='3' text='Music' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
<item child='0' id='4' text='Books' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
<item child='1' id='5' text='Movies' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
<item child='1' id='6' text='Photos' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
<item child='0' id='14' text='Articles' im0='folderClosed.gif' im1='folderOpen.gif' im2='folderClosed.gif'></item>
</tree>
---------------------------------------------------------------------------------------------------------------
I finally found the solution. The id attribute of the tree element must point to the parent id, which data will be linked, by default super-root ID = 0, but it can be changed while tree initialization ( 4th parameter of constructor ), In case of dynamic loading the tree id must be equal to the parent ID for which data requested.

In my database, the root id of the top level folder is 1, however, I use 0 in the tree initialization method.

---------------------------------------------------------------------------------------------------------------
tree=new dhtmlXTreeObject("treeboxbox_tree","100%","100%",0);

---------------------------------------------------------------------------------------------------------------
So, I got the exception. After changing the fourth parameter to 1, it works well.

tree=new dhtmlXTreeObject("treeboxbox_tree","100%","100%",1);

---------------------------------------------------------------------------------------------------------------