How to check if a variable exists in a FreeMarker template?

Question

I have a Freemarker template which contains a bunch of placeholders for which values are supplied when the template is processed. I want to conditionally include part of the

Answer 1

Also I think if_exists was used like:

Hi ${userName?if_exists}, How are you?

which will not break if userName is null, the result if null would be:

Hi , How are you?

if_exists is now deprecated and has been replaced with the default operator ! as in

Hi ${userName!}, How are you?

the default operator also supports a default value, such as:

Hi ${userName!"John Doe"}, How are you?