Twig过滤器链接和优先级

Question

I'm having diffculties trying to find the right syntax for a multiple Twig filter expression.

I have a var called floatVar which is not always defined.

If it is defined, I would like to truncate this float to the third digit. If it is not defined, I would like to set an empty string.

I'm having trouble finding the proper syntax:

floatVar|number_format(3, '.','')|default('') // generates a Twig_Error_Runtime exception

floatVar|default('')|number_format(3, '.','') // output "0" in every case

(floatVar|number_format(3, '.',''))|default('') // generates a Twig_Error_Runtime exception

Could somebody point me in the right direction ? Is there a way to put paranthesis to explictly express the priority ? Any help or link to a related topic would be much appreciated.

Have a good day.

Answer 1

The correct order would be :

{{ floatVar|default(0)|number_format(3, '.','') }}

• default(0) : first you ensure that floatVar has a default value (even if it's not defined)
• number_format(3, '.','') : then you format it

however, this would print 0.000 if floatvar isn't defined.

if you want to do this in 1 line, you should consider creating a custom twig extension : http://symfony.com/doc/current/cookbook/templating/twig_extension.html

EDIT : Following @Pierre Olivier's answer, you should try :

{{ floatVar is defined ? floatVar|number_format(3, '.','') : '' }}

(yourelement != null will raise an error if yourelement isn't defined)