# Switching From Other Template Engines

This is a brief guide on some of the differences between Jinja syntax and other template languages. See Template Designer Documentation for a comprehensive guide to Jinja syntax and features.

## Django

If you have previously worked with Django templates, you should find Jinja very familiar. Many of the syntax elements look and work the same. However, Jinja provides some more syntax elements, and some work a bit differently.

This section covers the template changes. The API, including extension support, is fundamentally different so it won’t be covered here.

Django supports using Jinja as its template engine, see https://docs.djangoproject.com/en/stable/topics/templates/#support-for-template-engines.

### Method Calls

In Django, methods are called implicitly, without parentheses.

    {% for page in user.get_created_pages %}
        ...
    {% endfor %}

In Jinja, using parentheses is required for calls, like in Python. This allows you to pass variables to the method, which is not possible in Django. This syntax is also used for calling macros.

    {% for page in user.get_created_pages() %}
        ...
    {% endfor %}

### Filter Arguments

In Django, one literal value can be passed to a filter after a colon.

    {{ items|join:", " }}

In Jinja, filters can take any number of positional and keyword arguments in parentheses, like function calls. Arguments can also be variables instead of literal values.

    {{ items|join(", ") }}

### Tests

In addition to filters, Jinja also has “tests” used with the `is` operator. This operator is not the same as the Python operator.

    {% if user.user_id is odd %}
        {{ user.username|e }} is odd
    {% else %}
        hmm. {{ user.username|e }} looks pretty normal
    {% endif %}

### Loops

In Django, the special variable for the loop context is called `forloop`, and the `empty` is used for no loop items.

    {% for item in items %}
        {{ forloop.counter }}. {{ item }}
    {% empty %}
        No items!
    {% endfor %}

In Jinja, the special variable for the loop context is called `loop`, and the `else` block is used for no loop items.

    {% for item in items %}
        {{ loop.index }}. {{ item }}
    {% else %}
        No items!
    {% endfor %}

### Cycle

In Django, the `{% cycle %}` can be used in a for loop to alternate between values per loop.

    {% for user in users %}
        <li class="{% cycle 'odd' 'even' %}">{{ user }}</li>
    {% endfor %}

In Jinja, the `loop` context has a `cycle` method.

    {% for user in users %}
        <li class="{{ loop.cycle('odd', 'even') }}">{{ user }}</li>
    {% endfor %}

A cycler can also be assigned to a variable and used outside or across loops with the `cycle()` global function.

## Mako

You can configure Jinja to look more like Mako:

    env = Environment(
        block_start_string="<%",
        block_end_string="%>",
        variable_start_string="${",
        variable_end_string="}",
        comment_start_string="<%doc>",
        commend_end_string="</%doc>",
        line_statement_prefix="%",
        line_comment_prefix="##",
    )

With an environment configured like that, Jinja should be able to interpret a small subset of Mako templates without any changes.

Jinja does not support embedded Python code, so you would have to move that out of the template. You could either process the data with the same code before rendering, or add a global function or filter to the Jinja environment.

The syntax for defs (which are called macros in Jinja) and template inheritance is different too.

The following Mako template:

    <%inherit file="layout.html" />
    <%def name="title()">Page Title</%def>
    <ul>
    % for item in list:
        <li>${item}</li>
    % endfor
    </ul>

Looks like this in Jinja with the above configuration:

    <% extends "layout.html" %>
    <% block title %>Page Title<% endblock %>
    <% block body %>
    <ul>
    % for item in list:
        <li>${item}</li>
    % endfor
    </ul>
    <% endblock %>