5.3 Conditionals - #if/#elseif/#else

The #if directive in Velocity allows for text to be included when the web page is generated, on the conditional that the if-statement is true. Consider the following piece of code:

#if( $display )
  <strong>Velocity!</strong>
#end

The variable $display is evaluated to determine whether it is true, which will happen under one of two circumstances:

The Velocity context only contains Java objects, so any method that returns a boolean primitive will automatically wrapped into a java.lang.Boolean object.

The content between the #if and the #end statements becomes the output if the evaluation is true. In this case, if $foo is true, the output will be: Velocity!. Conversely, if $foo has a null value, or if it is a boolean false, the statement evaluates as false, and there is no output.

An #elseif or #else element can be used with an #if element. Note that the Velocity Templating Engine will stop at the first expression that is found to be true:

Example 5.4. Using #if/#elseif/#else to select multiple template pieces

#set ($direction = 15)
#set ($wind = 6)

#if( $direction < 10 )
  <strong>Go North</strong>
#elseif( $direction == 10 )
  <strong>Go East</strong>
#elseif( $wind == 6 )
  <strong>Go South</strong>
#else
  <strong>Go West</strong>
#end

In this example, $direction is greater than 10, so the first two comparisons fail. Next $wind is compared to 6, which is true, so the output is Go South.

When you wish to include text immediately following a #else directive you need to use curly brackets immediately surrounding the directive to differentiate it from the following text:

#if( $foo == $bar)it's true!#{else}it's not!#end</li>