Template:If

Usage

{{if
  |test=VARIABLE_OR_PARAMETER_TO_TEST
  |then=code if 'test' is not empty
  |else=code if 'test' is empty
}}

Parameter else is optional. So you may also do:

{{if
  |test=VARIABLE_OR_PARAMETER_TO_TEST
  |then=code if 'test' is not empty
}}