How to concatenate strings in twig

Also a little known feature in Twig is string interpolation:

{{ "http://#{app.request.host}" }} 

The operator you are looking for is Tilde (~), like Alessandro said, and here it is in the documentation:

~: Converts all operands into strings and concatenates them. {{ "Hello " ~ name ~ "!" }} would return (assuming name is 'John') Hello John!. – http://twig.symfony.com/doc/templates.html#other-operators

And here is an example somewhere else in the docs:

{% set greeting = 'Hello' %} {% set name = 'Fabien' %} {{ greeting ~ name|lower }} {# Hello fabien #} {# use parenthesis to change precedence #} {{ (greeting ~ name)|lower }} {# hello fabien #} 

In this case, where you want to output plain text and a variable, you could do it like this:

http://{{ app.request.host }} 

If you want to concatenate some variables, alessandro1997's solution would be much better.

{{ ['foo', 'bar'|capitalize]|join }} 

As you can see this works with filters and functions without needing to use set on a seperate line.

Whenever you need to use a filter with a concatenated string (or a basic math operation) you should wrap it with ()'s. Eg.:

{{ ('http://' ~ app.request.host) | url_encode }}

You can use ~ like {{ foo ~ 'inline string' ~ bar.fieldName }}

But you can also create your own concat function to use it like in your question:
{{ concat('http://', app.request.host) }}:

In src/AppBundle/Twig/AppExtension.php

<?php namespace AppBundle\Twig; class AppExtension extends \Twig_Extension { /** * {@inheritdoc} */ public function getFunctions() { return [ new \Twig_SimpleFunction('concat', [$this, 'concat'], ['is_safe' => ['html']]), ]; } public function concat() { return implode('', func_get_args()) } /** * {@inheritdoc} */ public function getName() { return 'app_extension'; } } 

In app/config/services.yml:

services: app.twig_extension: class: AppBundle\Twig\AppExtension public: false tags: - { name: twig.extension } 

In Symfony you can use this for protocol and host:

{{ app.request.schemeAndHttpHost }} 

Though @alessandro1997 gave a perfect answer about concatenation.

Quick Answer (TL;DR)

• Twig string concatenation may also be done with the format() filter

Detailed Answer

Context

• Twig 2.x
• String building and concatenation

Problem

• Scenario: DeveloperGailSim wishes to do string concatenation in Twig
  • Other answers in this thread already address the concat operator
  • This answer focuses on the format filter which is more expressive

Solution

• Alternative approach is to use the format filter
• The format filter works like the sprintf function in other programming languages
• The format filter may be less cumbersome than the ~ operator for more complex strings

Example00

• example00 string concat bare

   {{ "%s%s%s!"|format('alpha','bravo','charlie') }} --- result -- alphabravocharlie! 

Example01

• example01 string concat with intervening text

   {{ "The %s in %s falls mainly on the %s!"|format('alpha','bravo','charlie') }} --- result -- The alpha in bravo falls mainly on the charlie! 

Example02

• example02 string concat with numeric formatting

• follows the same syntax as sprintf in other languages

   {{ "The %04d in %04d falls mainly on the %s!"|format(2,3,'tree') }} --- result -- The 0002 in 0003 falls mainly on the tree! 

See also

• http://twig.symfony.com/doc/2.x/filters/format.html
• https://stackoverflow.com/tags/printf/info

To mix strings, variables and translations I simply do the following:

 {% set add_link = ' <a class="btn btn-xs btn-icon-only" title="' ~ 'string.to_be_translated'|trans ~ '" href="' ~ path('acme_myBundle_link',{'link':link.id}) ~ '"> </a> ' %} 

Despite everything being mixed up, it works like a charm.

The "{{ ... }}"-delimiter can also be used within strings:

"http://{{ app.request.host }}"