Freemarker determines whether an object is empty

An object is displayed in Freemarker using ${name}.

But if name is Null,freemarker it will be an error. If you need to determine if the object is empty:

< #if name?? >

......

</#if >

Of course, you can also set the default value ${name! '} To avoid an empty object error. If name is empty, the default value ("!") The following characters) are displayed.

If the object User,name is a property of the user, User,name may be empty, then it can be written as ${(user.name)! '}, which indicates that user or name is null and is empty. Judged to be empty

< #if (user.name)?? >

......

</#if >

Freemarker determines whether an object is empty