Splitting field value inside field template not working?

Question

I have a twig template for some text field. Inside it I'm displaying the value like (it's single value field):

{% for item in items %}
  {{ item.content}}
{% endfor %}

And it's displaying value correctly, which means that inside that loop item.content contains correct value.

Now, field value actually contains tags, i.e. value is "tag1 tag2 tag 3". And I want to split that value by space sign. So I tried something like:

{% for item in items %}
  {% set tags = item.content|split(' ') %}
  {{ dump(tags) }}
  {{ item.content}}
{% endfor %}

And this split function should return list of elements 'tag1', 'tag2', 'tag3', according to documentation: https://twig.symfony.com/doc/2.x/filters/split.html

But instead, this dump call prints out null ?!?!

Why is that happening?

Answer 1

In a field.html.twig template {{ item.content }} is a render array. You can't use it in functions which expect a scalar like boolean, integer or string.

If you want to use field values in TWIG code better use the field object #items:

{% for item in element['#items'] %}
  {% set tags = item.value|split(' ') %}
  {{ dump(tags) }}
{% endfor %}

In a single value field you can access the value directly without a loop element['#items'].value.