How to concatenate strings in twig

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547

Anyone knows how to concatenate strings in twig? I want to do something like:

{{ concat('http://', app.request.host) }}

Woolpack answered 9/10, 2011 at 14:37 Comment(0)

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1046

This should work fine:

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

To add a filter - like 'trans' - in the same tag use

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

As Adam Elsodaney points out, you can also use string interpolation, this does require double quoted strings:

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

Lindbergh answered 9/10, 2011 at 16:33 Comment(8)

Thanks for you answer. But it appears that | trans filter doesn't work on that (eg: {{ 'test_' ~ name | trans }} won't translate my items. Do you have an idea how to do that? thx! – Mountainous 8/1, 2012 at 14:21

Yes, you have to create a variable to hold the concatenated string. E.g.: {% set foo = 'http://' ~ app.request.host %}. And then you can do: {{ foo | trans }}. – Lindbergh 8/1, 2012 at 17:58

Translation in one line: {{ ('test_' ~ name) | trans }} – Beaudry 4/3, 2012 at 10:11

Thank you. So the problem is that filters have higher precedence than the concatenation operator. – Lindbergh 4/3, 2012 at 14:31

This worked for me to concat strings passed into a function as one argument, with filters on the variable and the function token itself: {{ form_open('admin/files/?path='~file_path|urlencode)|raw }} No need for an extra variable. – Cribbing 9/3, 2012 at 6:28

Thanks for your post!! It did save me much time solving this issue. – Beetner 18/6, 2014 at 7:20

Thank you! Wrapping the concatenation in parenthesis helped with trans. – Urease 26/4, 2017 at 7:33

Please note, that the hash-sign must be before the open curly brace to make it interpolate. Also it must be double quotes. – Burnet 8/8, 2017 at 11:0

E

119

Also a little known feature in Twig is string interpolation:

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

Echinate answered 11/7, 2014 at 8:44 Comment(1)

Nice feature. Be aware, double-quoted strings only! – Carafe 18/11, 2014 at 9:15

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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 #}

Gaslight answered 1/2, 2014 at 13:30 Comment(0)

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22

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.

Glint answered 9/10, 2011 at 17:49 Comment(1)

this does not work for me, cause i have to url_encode the whole string with another filter... – Woolpack 10/10, 2011 at 8:3

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

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

Janusfaced answered 11/6, 2012 at 12:15 Comment(0)

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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 }}

These answered 28/7, 2013 at 17:53 Comment(1)

Very helpful, thanks. I needed to concatenate variables for use as a translation key. – Writeoff 15/1, 2014 at 18:44

H

9

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 }

Horsepower answered 10/11, 2015 at 22:58 Comment(0)

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6

In Symfony you can use this for protocol and host:

{{ app.request.schemeAndHttpHost }}

Though @alessandro1997 gave a perfect answer about concatenation.

Nephro answered 7/5, 2013 at 16:26 Comment(0)

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5

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!