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Building trees from HTML markup or from previous definitions.

Tree from markup

  • List 0
  • List 1
    • List 1-0
      • 02/01/2009
      • item 1-1-0

Copy of the tree above taken from its own definition

Copy of the second branch of the tree at the top

Tree built from a static definition

In this brief example for the TreeView Control, we begin with a <div> containing a set of nested unordered lists <ul> providing the basic tree structure.

Each <li> element in the markup will produce a Node. List-items with plain text will produce regular TextNodes, those with the className "expanded" will override the default of showing nodes collapsed. The list-item with a link will also produce a TextNode with its href and target properties set accordingly. The list-item containing a date, being a string, would normally create a TextNode, but it has been overridden by the use of the yuiConfig attribute to make it a DateNode and editable. The final node contains formatted text which will produce an HTMLNode; the whole has to be enclosed in a single HTML element to let the parser know how far it reaches.

We create a new TreeView and render it. The TreeView will read the existing HTML and build the nodes from it. We also subscribe to the dblClickEvent to enable editing to prove the DateNode is really such and is editable.

Once we have a tree, we can read its definition, preserve it somehow and then build an identical tree from it. In the second part we are building a couple of trees, one identical to the full tree and another one from just a branch of it

For tree2 we have used the full tree definition from the first tree. For tree3 we have first located a branch, for this sample, the second branch from the root and used its definition for the tree

Finally, in the last tree, we used an object literal to define the full tree.

Here we provide as a second argument to the constructor an array where each item can be either an object literal or a simple string, such as 'Label 0', which will be converted to a simple TextNode.

The items in the array can also be objects containing more detailed definitions for each node. All require a type property using either a short-name such as 'Text' or 'HTML' (case-insensitive) or the object name of the node type like 'MenuNode', which will be resolved to YAHOO.widget.MenuNode.

Object definitions allow precise control over the tree since any public property of each node can be specified, for example, some nodes start expanded while others collapsed. We cannot have such expressiveness from plain HTML markup.

We have defined a couple of external links. In the first one, labeled YAHOO, the link has the generic style of the rest of the nodes in the tree. In the second one, labeled YUI, we have used an HTMLNode instead of a TextNode so TreeView copies that string into the node without adding further classNames so it gets a different look.

The last node, being a MenuNode, forces other branches to collapse when expanded. The other node with children, being a plain node doesn't mind if other nodes remain expanded.

Nodes may contain a children property containing further node definitions.