How do I test if a field has a value in twig?

Question

I am writing a template and if 2 fields, one of which is required the other is not. I would like to display the one thats not required if has been filled out by the user.

I have tried numerous things

{% if content.not_required %}
 {{ content.not_required }}
{%else%}
  {{ content.required }}

{% if content.not_required  is null %}
 {{ content.required }}  
{%else%}
  {{ content.required }}  

{% if content.not_required  == false %}
 {{ content.required }}
{%else%}
  {{ content.required }}

{% if content.not_required  == null %}
 {{ content.required }}
{%else%}
  {{ content.required }}

{% if not  content.not_required %}
 {{ content.required }}
{%else%}
  {{ content.required }}

all of these display all stories the same whether or not content.not_required was filled in.

Is there a way to do this in twig or do I need to set up some variable in a preprocess function?

Answer 1

There is an issue about this on Drupal.org: Checking for empty fields in Twig templates is complicated.

Use the following syntax and keep an eye on updates:

{% if content.not_required|render %}
    {{ content.not_required }}
{% else %}
    {{ content.required }}
{% endif %}

Answer 2

First, you are not referencing the field name right. All fields from Drupal are prefixed as field_. So it should be field_not_required if you created the field.

You also don't need a module, you don't need to check the render array. You can just do {% if node.field_name is not empty %} which is standard Twig. This also works for any entity that passes its data object into the template, like Paragraphs or Media.

Here is an example from an actual project:

  <div class="hero__content">
    {% if node.field_hero_title is not empty %}
      {{ content.field_hero_title }}
    {% else %}
      <h2 class="hero__title">{{ node.label }}</h2>
    {% endif %}

    {% if node.field_hero_subtitle is not empty %}
      {{ content.field_hero_subtitle }}
    {% endif %}

    {% if node.bundle == 'article' %}
      <h5 class="hero__description">{{ node.getCreatedTime|format_date('article_full_date') }}</h5>
    {% endif %}

    {% if node.field_hero_description is not empty %}
      {% autoescape %}
        {{ content.field_hero_description }}
      {% endautoescape %}
    {% endif %}
  </div>

This checks to see that the field is not empty before rendering the render array in the template.

If the field you are using is a boolean:

{% if node.field_not_required.value == 1 %}

Answer 3

The solution is to install this module: twig_field_value

With this module you can drill down to the effective content of a field, without the wrappers or standard field-labels (html-wrappers or labels can give the false impresion of a field not being empty in a -n "if statement"). By adding this code"|field_value", you can get only the bare value only of a field:

{{ content.field_name|field_value }}

Now you use a simple Twig if statement to see if a field is really not empty:

{% if content.field_name|field_value %}
    <p>Field "field_name" is not empty, the value is {{ content.field_name|field_value }}</p>
{% endif %}