A basic example of <if>

This section will show a simple example of how we use <if> in a web page.

After reading this section you will understand how to use <if> with the Match plugin.

We will create a feature on the DemoLabs Inc. site (shipped with Roxen WebServer). This feature includes the possiblity to toggle between short view and long view using a button while reading a protocol in the Management Protocol Archive. The short view only displays the header of the protocol, while long view shows the full protocol.

Short/Long feature in protocols

Imagine that the protocols tend to be rather long and that someone only wants to check which persons were present and what issuses that were discussed during a meeting. Wouldn't it be nice only to view a 'header' of the protocol per default, containing these data. The whole protocol should only be displayed when the user explicitly requests that. To accomplish this we add some RXML and a button. The button will be used to toggle between viewing the whole protocol and only the 'header'.

Since we want every new protocol file to have this feature we will edit the Stationary Protocol file protocol.html. This is a default protocol file that is used as a foundation for creating new protocol files. At the top of this file we add the following code:

<!-- Page loaded first time -->
<if match='&form.request; is '>
  <form method='POST'>
    <input type='hidden' name='request' value='long' />
    <submit-gnutton gnutton='gnutton5' align='left'
    >Long view</submit-gnutton>
    <br /><br />
  </form>
</if>

<!-- When long mode is requested -->
<elseif match='&form.request; is long'>
  <form method='POST'>
    <input type='hidden' name='request' value='short' />
    <submit-gnutton gnutton='gnutton5' align='left'
    >Short view</submit-gnutton>
    <br /><br />
  </form>
</elseif>

<!-- When short mode is requested -->
<else>
  <form method='POST'>
    <input type='hidden' name='request' value='long' />
    <submit-gnutton gnutton='gnutton5' align='left'
    >Long view</submit-gnutton>
    <br /><br />
  </form>
</else>

Before the line <h1>Opening</h1>, which is the starting header for the full view mode we add an <if> test. Only if the user requests long view the content between <if> and </if> will be sent to the browser. Finally we add </if> at the last line of the file.

<if match='&form.request; is '>
  <h1>Opening</h1>
    ...
</if>

This will result in the following button and short form of the protocol file when loaded the first time:

The text displayed in the short form protocol with button added on top.

The trick is to dynamically insert the right form depending on which view is requested. This is accomplished with an if-elseif-else statement. <if> checks for an empty &form.request;. This will only be the case the first time the page is loaded. <elseif> catches the case when long view is requested and <else> the case when short view is requested.

<if match='&form.request; is '>
  ...
</if>
<elseif match='&form.request; is long'>
  ...
</elseif>
<else>
  ...
</else>

The inserted form contains a hidden field with its request variable set to the mode that will be requested on submit and a special XSLT defined button - <submit-gnutton> - with its displayed text set inside the container. XSLT is not in the scope of this Lesson, so we will leave that with telling this is used only to get a nice look-&-feel.

<form method='POST'>
  <input type='hidden' name='request' value='long' />
  <submit-gnutton gnutton='gnutton5' align='left'
  >Long view</submit-gnutton>
  <br /><br />
</form>

You could use an ordinary submit button as well:

<input type='submit' value='long' />

Well, there it is! Finally, let's have a look at a part of the long view version of a protocol page:

The button inserted on a long view protocol page.

Summary

This section has shown a basic example of how to use the <if> plugin Match.

More details about <if> and If Plugins are found in the Web Site Creator Manual and/or by adding <help for='if' /> in a web page.

The next section, Combining <if> and <define> will teach the basics of how to use <if> and <define> to dynamically display contents in a web page.