XForms/Select and Group

< XForms

Motivation

You want to conditionally display a group of elements based on the value selected from a list. This will work similar to a "switch/case" but you can have each view depend on complex XPath expressions that will evaluated to either true or false.

Screen Image

In the screen image above, the second item is selected. When a different item is selected, the view under the select list changes.

Sample Program 

<html
   xmlns="http://www.w3.org/1999/xhtml"
   xmlns:xf="http://www.w3.org/2002/xforms">
   <head>
      <title>Dynamically bind to a group</title>
      <!-- Using bind and relevant in the model to conditionally display a group -->
      <!-- Alternative to switch/case/toggle when the id of toggle is dynamically calculated -->
      <style type="text/css">
      @namespace xf url("http://www.w3.org/2002/xforms");
      xf|group {
         border: solid black 2px;
         background-color: silver;
         height: 100px;
      }
      xf|group xf|label {
         position: relative;
         font-family: Helvetica, sans-serif;
         font-weight: bold;
         background-color: white;
         padding: 2px;
         top: -10px;
         left: 10px;
      }
      xf|group p {
         position: relative;
         top: -30px;
         padding: 5px;
      }
      </style>
      <xf:model>
         <xf:instance>
            <data xmlns="">
               <current-view>one</current-view>
               <view-1>one</view-1>
               <view-2>two</view-2>
               <view-3>three</view-3>
            </data>
         </xf:instance>
         <!-- if the current-view is 'one' make the view-1 group relevent (visible)-->
         <xf:bind nodeset="view-1" relevant="../current-view= 'one'" />
         <xf:bind nodeset="view-2" relevant="../current-view = 'two'" />
         <xf:bind nodeset="view-3" relevant="../current-view = 'three'" />
      </xf:model>
   </head>
   <body>
         <xf:select1 ref="current-view">
            <xf:label>Select View: </xf:label>
            <xf:item>
               <xf:label>One</xf:label>
               <xf:value>one</xf:value>
            </xf:item>
            <xf:item>
               <xf:label>Two</xf:label>
               <xf:value>two</xf:value>
            </xf:item>
            <xf:item>
               <xf:label>Three</xf:label>
               <xf:value>three</xf:value>
            </xf:item>
         </xf:select1>
         <br/>
         <!-- only one of the three outputs will display -->
         <xf:output ref="view-1">
            <xf:label>Current view: </xf:label>
         </xf:output>
         <xf:output ref="view-2">
            <xf:label>Current view: </xf:label>
         </xf:output>
         <xf:output ref="view-3">
            <xf:label>Current view: </xf:label>
         </xf:output>
         <br/>
         <br/>
         <!-- only a single group will be displayed at any time -->
         <xf:group ref="view-1">
            <xf:label>View One</xf:label>
            <p>One One One One One One One One One One One One One One One One One One</p>
         </xf:group>
         <xf:group ref="view-2">
            <xf:label>View Two</xf:label>
            <p>Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two Two</p>
         </xf:group>
         <xf:group ref="view-3">
            <xf:label>View Three</xf:label>
            <p>Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three Three</p>
         </xf:group>
   </body>
</html>

Discussion

This program is very similar to the example that uses a button to toggle a switch/case but the value is calculated dynamically by any XPath expression. The prior example that uses switch/case/toggle uses an XML Event to make a specific case visible.

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