[Twig] A Comprehensive Guide to Conditional Statements (if)

I'd like to introduce how to use Twig's conditional statements, including some common real-world scenarios.

HOW TO USE IF STATEMENTS IN TWIG

Checking if an expression is true

html

{% if testCase == false %}
    <p>"testCase" is false.</p>
{% endif %}

Checking if a variable's value is true

javascript

{# user is variable #}
{% if user %}
    <p>{{ user }} is your ID.</p>
{% endif %}

{# users is array. You can also test if an array is not empty #}
{% if users %}
    <ul>
        {% for user in users %}
            <li>{{ user.name }}</li>
        {% endfor %}
    </ul>
{% endif %}

Using AND and OR operators

html

{% if user.age > 18 and user.age < 40 %}
    <p>Youth</p>
{% endif %}

{% if user.city == 'tokyo' or user.city == 'osaka' %}
    <p>live in Tokyo or Osaka</p>
{% endif %}

How to write elseif and else

css

{% if product.stock > 10 %}
   Available
{% elseif product.stock > 0 %}
   {{ product.stock }} left
{% else %}
   Sold Out
{% endif %}

EXAMPLES OF IF STATEMENTS IN TWIG

I'd like to introduce some common use cases, including the various syntax you can use within Twig's if statements.

Checking if a variable is defined

css

{% if product.name is defined %}
    <div>{{ product.name }} is in stock.</div>
{% endif %}

{# You can use is not defined #}
{% if product.name is not defined %}
    <div>the product is out of stock.</div>
{% endif %}

Checking for null values

html

{% if user is null %}
    <p>new user</p>
{% endif %}

Strictly checking values (equivalent to `===`)

html

{% if user.age is sameas(40) %}
    <p>Middle-aged</p>
{% endif %}

Checking with regular expressions

html

{% if phone matches '/^[\\d\\.]+$/' %}
   <p>{{ phone }}</p>
{% endif %}

Checking the first or last character

css

{% if 'Tokyo' starts with 'T' %}
{% endif %}

{% if 'Tokyo' ends with 'o' %}
{% endif %}

RECOMMENDED BOOKS FOR TWIG

While I haven't personally read any books exclusively dedicated to Twig, I found one on Amazon Kindle.

📦

Amazon で関連書籍・ツールを検索

PHP Twig template engine

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