nnA list literal is a sequence of comma-separated values, enclosed in square brackets ([...]). Lists are useful for storing sequential data that you need to iterate over, such as a collection of items, user accounts, or navigation links. Lists are also mutable, meaning you can change their contents.nn

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How It Works

nJinja2 recognizes any sequence of values within square brackets as a list. Lists can hold a mix of different data types, including strings, numbers, booleans, and even other lists or tuples. A key feature of lists is that they are ordered, meaning you can access elements by their index, starting from 0.nnLists are most commonly used in conjunction with a for loop to iterate through each item and perform an action, such as displaying each item as a list entry or building a navigation menu.n

Syntax

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{{ ['item1', 'item2', 'item3'] }}n{% set my_list = [1, 2, 3] %}

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Demonstration with Code Samples

nHere are some practical examples of how to use list literals in a Jinja2 application.n

1. Using a List in a `for` Loop

nThis is a powerful and common use case for lists, particularly when iterating over a collection of data, such as a set of links.nnJinja2 Templaten

<ul>n{% for href, caption in [('index.html', 'Index'), ('about.html', 'About'), ('downloads.html', 'Downloads')] %}n    <li><a href="{{ href }}">{{ caption }}</a></li>n{% endfor %}n</ul>

nExplanation: This template iterates over a list of tuples. In each iteration, it unpacks the tuple into the `href` and `caption` variables. It then uses these variables to create an HTML list item with a link, demonstrating how you can build dynamic content from a list of structured data.nn

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2. Accessing List Elements by Index

nYou can retrieve individual elements from a list by specifying their index. Remember that indexing is zero-based.nnJinja2 Templaten

{% set fruits = ['apple', 'banana', 'cherry'] %}n<p>The first fruit is: {{ fruits[0] }}</p>n<p>The last fruit is: {{ fruits[-1] }}</p>

nExplanation: This example shows how to access the first element using `[0]` and the last element using the negative index `[-1]`. The output will be the values “apple” and “cherry”, respectively.nn

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3. Storing Different Data Types

nA single list can hold a variety of data types, making it a flexible container for a collection of related values.nnJinja2 Templaten

{% set profile_data = ['John Doe', 30, True, 'New York'] %}n<ul>n    <li>Name: {{ profile_data[0] }}</li>n    <li>Age: {{ profile_data[1] }}</li>n    <li>Is Active: {{ profile_data[2] }}</li>n    <li>City: {{ profile_data[3] }}</li>n</ul>

nExplanation: The `profile_data` list contains a string, an integer, a boolean, and another string. The template then accesses and displays each item by its index, showing how a list can be used to store and present a simple record of information.nn