> For the complete documentation index, see [llms.txt](https://azutopia.gitbook.io/azu/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://azutopia.gitbook.io/azu/templates-1/engine.md). # Template Engine Azu uses Crinja, a Jinja2-compatible template engine. ## Basic Syntax ### Variables Output variables with `{{ }}`: ```html

{{ title }}

{{ user.name }}

{{ items[0] }}

``` ### Tags Control flow with `{% %}`: ```html {% if user %}

Hello, {{ user.name }}

{% endif %} ``` ### Comments ```html {# This is a comment #} {# Multi-line comment #} ``` ## Control Structures ### if / elif / else ```html {% if user.admin %} Admin {% elif user.moderator %} Moderator {% else %} User {% endif %} ``` ### for Loop over collections: ```html {% for item in items %}
  • {{ item.name }}
    • {% endfor %} {% for item in items %}
  • {{ item }}
    • {% else %}
  • No items found
    • {% endfor %} ``` **Loop Variables:** | Variable | Description | | --------------- | -------------------------------- | | `loop.index` | Current iteration (1-indexed) | | `loop.index0` | Current iteration (0-indexed) | | `loop.first` | True on first iteration | | `loop.last` | True on last iteration | | `loop.length` | Total number of items | | `loop.revindex` | Iterations until end (1-indexed) | ```html {% for user in users %} {{ loop.index }} {{ user.name }} {% endfor %} ``` ### for with conditions ```html {% for user in users if user.active %}
  • {{ user.name }}
    • {% endfor %} ``` ## Template Inheritance ### extends Extend a base template: ```html {% extends "layouts/base.html" %} ``` ### block Define overridable blocks: ```html {% block title %}Default Title{% endblock %} {% block content %}{% endblock %} ``` ```html {% extends "layouts/base.html" %} {% block title %}Home Page{% endblock %} {% block content %}

    Welcome!

    {% endblock %} ``` ### super Access parent block content: ```html {% block content %} {{ super() }}

    Additional content

    {% endblock %} ``` ## Includes ### include Include another template: ```html {% include "partials/header.html" %} {% include "partials/footer.html" %} ``` ### include with context ```html {% include "partials/user_card.html" with user=current_user %} {% include "partials/item.html" with item=item, index=loop.index %} ``` ### include with ignore missing ```html {% include "partials/optional.html" ignore missing %} ``` ## Macros ### Define macros ```html {% macro input(name, value="", type="text") %} {% endmacro %} ``` ### Use macros ```html {{ input("username") }} {{ input("email", user.email, "email") }} {{ input("password", type="password") }} ``` ### Import macros ```html {% import "macros/forms.html" as forms %} {{ forms.input("name") }} ``` ## Filters Filters transform values: ```html {{ name | upper }} {{ name | lower }} {{ name | capitalize }} {{ name | title }} ``` ### String Filters | Filter | Description | Example | | --------------- | ------------------- | ------------------ | | `upper` | Uppercase | \`{{ "hello" | | `lower` | Lowercase | \`{{ "HELLO" | | `capitalize` | Capitalize first | \`{{ "hello" | | `title` | Title case | \`{{ "hello world" | | `trim` | Remove whitespace | \`{{ " hello " | | `truncate(n)` | Truncate to n chars | \`{{ text | | `replace(a, b)` | Replace substring | \`{{ name | | `striptags` | Remove HTML tags | \`{{ html | ### Number Filters | Filter | Description | Example | | ---------- | ------------------- | ------------ | | `abs` | Absolute value | \`{{ -5 | | `round` | Round number | \`{{ 3.7 | | `round(n)` | Round to n decimals | \`{{ 3.14159 | ### List Filters | Filter | Description | Example | | ----------- | ------------------- | ---------- | | `length` | Get length | \`{{ items | | `first` | First item | \`{{ items | | `last` | Last item | \`{{ items | | `join(sep)` | Join with separator | \`{{ items | | `sort` | Sort list | \`{{ items | | `reverse` | Reverse list | \`{{ items | ### Escape Filters | Filter | Description | | -------------- | ------------------------ | | `escape` / `e` | HTML escape | | `safe` | Mark as safe (no escape) | | `urlencode` | URL encode | ### Default Filter ```html {{ value | default("N/A") }} {{ user.name | default("Anonymous") }} ``` ### Chaining Filters ```html {{ name | trim | lower | truncate(20) }} ``` ## Tests Test values with `is`: ```html {% if number is even %} {% if name is defined %} {% if items is empty %} {% if value is none %} {% if text is string %} ``` ### Available Tests | Test | Description | | ----------- | --------------------- | | `defined` | Variable is defined | | `undefined` | Variable is undefined | | `none` | Value is nil | | `empty` | Collection is empty | | `even` | Number is even | | `odd` | Number is odd | | `string` | Value is string | | `number` | Value is number | | `iterable` | Value is iterable | ## Operators ### Comparison ```html {% if age >= 18 %} {% if status == "active" %} {% if name != "" %} ``` ### Logical ```html {% if user and user.active %} {% if admin or moderator %} {% if not banned %} ``` ### Math ```html {{ price * quantity }} {{ total / items }} {{ count + 1 }} {{ index % 2 }} ``` ### String Concatenation ```html {{ first_name ~ " " ~ last_name }} ``` ### In Operator ```html {% if "admin" in roles %} {% if user.id in allowed_ids %} ``` ## Whitespace Control Remove whitespace with `-`: ```html {% for item in items -%} {{ item }} {%- endfor %} ``` ## Raw Output Disable processing: ```html {% raw %} This {{ will not }} be processed {% endraw %} ``` ## See Also * [How to Render HTML Templates](/azu/templates/render-html-templates.md) * [How to Enable Hot Reload](/azu/templates/enable-hot-reload.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://azutopia.gitbook.io/azu/templates-1/engine.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.