Ternary operators in Twig php (Shorthand form of if-then-else)

问题

Is it possible to use ternary operators in twig template? Now, for adding some class to DOM element depend on some condition I do like this:

{%if ability.id in company_abilities%}
    <tr class="selected">
{%else%}
    <tr>
{%endif%}

Instead of

<tr class="<?=in_array($ability->id, $company_abilities) ? 'selected' : ''?>">

in native php template engine.

回答1:

{{ (ability.id in company_abilities) ? 'selected' : '' }}

The ternary operator is documented under 'other operators'

回答2:

You can use shorthand syntax as of Twig 1.12.0

{{ foo ?: 'no' }} is the same as {{ foo ? foo : 'no' }}
{{ foo ? 'yes' }} is the same as {{ foo ? 'yes' : '' }}

回答3:

The ternary operator (?:)

Support for the extended ternary operator was added in Twig 1.12.0.

1. Case #1

   Snippet:

   {{ foo ? 'yes' : 'no' }}
   

   Evaluates:

   if foo echo yes else echo no

   ---

2. Case #2

   Snippet:

   {{ foo ?: 'no' }}
   

   or

   {{ foo ? foo : 'no' }}
   

   Evaluates:

   if foo echo it, else echo no

   ---

3. Case #3

   Snippet:

   {{ foo ? 'yes' }}
   

   or

   {{ foo ? 'yes' : '' }}
   

   Evaluates:

   if foo echo yes else echo nothing

---

The null-coalescing operator (??)

1. Case #1

   Snippet:

   {{ foo ?? 'no' }}
   

   Evaluates:

   Returns the value of foo if it is defined and not null, no otherwise

Note: this is slightly different from {{ foo|default('no') }}, since the latter will be triggered also from empty values like ''.

来源：https://stackoverflow.com/questions/11820297/ternary-operators-in-twig-php-shorthand-form-of-if-then-else