New Sample Demonstrating the Traversing of Tree Bindings

Posted by Duncan Mills on Oracle Blogs See other posts from Oracle Blogs or by Duncan Mills
Published on Tue, 3 Jul 2012 09:12:44 +0000 Indexed on 2012/07/03 15:21 UTC
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A technique that I seem to use a fair amount, particularly in the construction of dynamic UIs is the use of a ADF Tree Binding to encode a multi-level master-detail relationship which is then expressed in the UI in some kind of looping form – usually a series of nested af:iterators, rather than the conventional tree or treetable. This technique exploits two features of the treebinding. First the fact that an treebinding can return both a collectionModel as well as a treeModel, this collectionModel can be used directly by an iterator. Secondly that the “rows” returned by the collectionModel themselves contain an attribute called .children. This attribute in turn gives access to a collection of all the children of that node which can also be iterated over.

Putting this together you can represent the data encoded into a tree binding in all sorts of ways.

As an example I’ve put together a very simple sample based on the HT schema and uploaded it to the ADF Sample project. It produces this UI:

Example output from this technique

The important code is shown here for a Region -> Country -> Location Hierachy:

<af:iterator id="i1" value="#{bindings.AllRegions.collectionModel}" var="rgn">
  <af:showDetailHeader text="#{rgn.RegionName}" disclosed="true" id="sdh1">
    <af:iterator id="i2" value="#{rgn.children}" var="cnty">
      <af:showDetailHeader text="#{cnty.CountryName}" disclosed="true" id="sdh2">
        <af:iterator id="i3" value="#{cnty.children}" var="loc">
          <af:panelList id="pl1">
            <af:outputText value="#{loc.City}" id="ot3"/>
          </af:panelList>
        </af:iterator>
      </af:showDetailHeader>
    </af:iterator>
  </af:showDetailHeader>
</af:iterator> 

You can download the entire sample from here:

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