Handling null values in freemarker using if condition

From: http://stackoverflow.com/questions/306732/how-to-check-if-a-variable-exists-in-a-freemarker-template

Two solutions:

First Solution:

Example 1:

<#if userName??>
   Hi ${userName}, How are you?
</#if>

Example 2:

<#if router.cableFacility.direction??>
   Hi ${router.cableFacility.direction}, How are you?</#if>

Second Solution:

Hi ${userName!}, How are you?


the default operator also supports a default value, such as:
Hi ${userName!"John Doe"}, How are you?