Template Syntax

PHP-Jinja uses a syntax similar to the Python Jinja2 template engine. This document covers the core syntax elements.

Delimiters

PHP-Jinja uses three types of delimiters:

• {{ ... }}: Output expressions - prints the result of an expression
• {% ... %}: Control structures - for loops, if statements, etc.
• {# ... #}: Comments - not rendered in the output

Variables

Access variables using the double curly braces:

{{ name }}                  <!-- Simple variable -->
{{ user.name }}             <!-- Object/array property access using dot notation -->
{{ array.0 }}               <!-- Array index access using dot notation -->
{{ array[0] }}              <!-- Array index access using bracket notation -->
{{ user['name'] }}          <!-- Associative array access using bracket notation -->
{{ nested['key'][0].prop }} <!-- Combined notation is also supported -->

Expressions

Literals

{{ 42 }}                      <!-- Integer -->
{{ 3.14 }}                    <!-- Float -->
{{ "hello" }} or {{ 'hello' }} <!-- Strings -->
{{ true }}, {{ false }}       <!-- Booleans -->
{{ [1, 2, 3] }}               <!-- Array -->
{{ ['a': 1, 'b': 2] }}        <!-- Associative array -->

Operators

Mathematical

{{ 1 + 2 }}    <!-- Addition: 3 -->
{{ 5 - 2 }}    <!-- Subtraction: 3 -->
{{ 2 * 3 }}    <!-- Multiplication: 6 -->
{{ 6 / 2 }}    <!-- Division: 3 -->
{{ 7 % 3 }}    <!-- Modulo: 1 -->
{{ 2 ** 3 }}   <!-- Exponentiation: 8 -->

String Concatenation

{{ "Hello" ~ " " ~ "World" }}  <!-- "Hello World" -->

Comparison

{{ 1 == 1 }}   <!-- Equal: true -->
{{ 1 != 2 }}   <!-- Not equal: true -->
{{ 1 < 2 }}    <!-- Less than: true -->
{{ 2 > 1 }}    <!-- Greater than: true -->
{{ 1 <= 1 }}   <!-- Less than or equal: true -->
{{ 1 >= 1 }}   <!-- Greater than or equal: true -->

Logical

{{ true && false }}  <!-- Logical AND: false -->
{{ true || false }}  <!-- Logical OR: true -->
{{ !true }}          <!-- Logical NOT: false -->

Membership Test

{{ "a" in "abc" }}      <!-- String contains: true -->
{{ 1 in [1, 2, 3] }}    <!-- Array contains: true -->

Control Structures

Conditionals

{% if condition %}
    Content rendered if condition is true
{% elif condition2 %}
    Content rendered if condition2 is true and previous conditions were false
{% elif condition3 %}
    Content rendered if condition3 is true and previous conditions were false
{% else %}
    Content rendered if condition is false
{% endif %}

Whitespace control:

{%- if condition -%}
    Content without whitespace before or after
{%- endif -%}

Loops

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

For loops with an else block (executed when the loop array is empty):

{% for item in items %}
    {{ item }}
{% else %}
    No items found.
{% endfor %}

The else clause in a for loop provides a way to handle empty collections. When the collection being iterated is empty (has no items), the content inside the else block is rendered instead of the loop body. This is useful for displaying alternative content or messages when there are no items to process.

Examples:

{# Display a list of users or a message if no users exist #}
<ul>
    {% for user in users %}
        <li>{{ user.name }}</li>
    {% else %}
        <li>No users found</li>
    {% endfor %}
</ul>

{# Generate table rows or show "empty" message #}
<table>
    <tr><th>Name</th><th>Email</th></tr>
    {% for contact in contacts %}
        <tr>
            <td>{{ contact.name }}</td>
            <td>{{ contact.email }}</td>
        </tr>
    {% else %}
        <tr><td colspan="2">Address book is empty</td></tr>
    {% endfor %}
</table>

{# Conditionally show content when a list exists and has items #}
{% for notification in notifications %}
    <div class="alert">{{ notification.message }}</div>
{% else %}
    {# Nothing is rendered when notifications is empty #}
{% endfor %}

Whitespace control can be used with for-else loops as well:

{# Trim whitespace after the opening for tag #}
{% for item in items -%}
    {{ item }}
{% else %}
    No items
{% endfor %}

{# Trim whitespace before the else tag #}
{% for item in items %}
    {{ item }}
{%- else %}
    No items
{% endfor %}

Loop variables:

{% for item in items %}
    {{ loop.index }}   <!-- 1-based index -->
    {{ loop.index0 }}  <!-- 0-based index -->
    {{ loop.first }}   <!-- true if first iteration -->
    {{ loop.last }}    <!-- true if last iteration -->
    {{ loop.length }}  <!-- total number of items -->
{% endfor %}

Nested For Loops

For loops can be nested inside each other:

{% for category in categories %}
  <h2>{{ category.name }}</h2>
  {% for product in category.products %}
    <div>{{ product.name }}: ${{ product.price }}</div>
  {% endfor %}
{% endfor %}

For-else blocks can be used in nested structures, but with some limitations:

{% for category in categories %}
  <h2>{{ category.name }}</h2>
  {% for product in category.products %}
    <div>{{ product.name }}: ${{ product.price }}</div>
  {% endfor %}
{% else %}
  <p>No categories available</p>
{% endfor %}

Note: Currently, the template engine supports else clauses in outer for loops but has limited support for else clauses in inner for loops. For best results, use for-else only on the outermost loop level.

Comments

Add comments that are not rendered in the output:

{# This is a comment that won't appear in the output #}