How to use if else in Jinja2

by gayathrimohan Updated: Nov 17, 2023

Solution Kit

Jinja2 is a powerful and used templating engine for Python. It allows you to embed dynamic content within templates.

Here are some basics:

Syntax:

Variables: Enclosed in double curly braces, like {{ variable_name }}.
Expressions: Use filters, like {{ variable_name|filter_name }}.
Control Statements: Use {% %} tags for if statements, loops, and other control flow.

Features:

Template Inheritance: Allows you to create a base template. Also allows you to extend blocks in child templates.
Variables: Insert data into templates by passing variables from Python code.
Control Statements: Use {% %} for conditional statements, loops, and other control flow structures.
Filters: Change variable output using filters, such as {{ variable|filter_name }}.
Macros: Define reusable components with macros to avoid redundancy in templates.
Comments: Add comments within templates using {# #}.
Template Context: Access context variables and functions within templates.

In Jinja2, you can use conditional statements like if, elif, and else to control the flow of your templates. Jinja2 is a powerful templating engine for Python. It allows you to embed dynamic content in templates. To create loops in Jinja2, you can use the {% for %} loop for iterating over sequences. You can {% while %} loop for executing code while a certain condition is true.

For Loop: iterable is the sequence you want to loop through. This item is the variable that holds each element of the sequence during each iteration.
While Loop: The content inside the {% while %} loop will repeat if the condition counter is true.

Jinja2's looping constructs are flexible and can handle various scenarios. This makes it a versatile tool for generating dynamic content in templates. Jinja2 is a templating engine for Python, used with web frameworks like Flask. It is not designed for creating functions with explicit return within templates. But you can use Jinja2 to generate dynamic content in templates.

For example, in a Flask application:

Install Jinja2: pip install Jinja2
Create a Flask App
Create a Jinja2 Template (e.g., index.html)

Here are some tips for creating efficient and effective code using Jinja2:

Use Named Blocks: Named blocks make your templates more modular and reusable.
Nesting Blocks: You can nest blocks within other blocks to create a hierarchy of content.
Template Inheritance: Leverage template inheritance to create a base template. That defines the common structure of your pages.
Filters and Functions: Take advantage of Jinja2 filters and functions. Those manipulate data within your templates.
Conditional Statements: Use {% if %} and {% else %} statements. It controls the flow of your templates.
Loops: Use {% for %} loops to iterate over lists or other iterable objects. This is particularly useful for generating repetitive HTML structures.
Macro Definitions: Macros allow you to define reusable components within your templates.
Whitespace Control: Use the {%- and -%} markers to control leading and trailing whitespace. Use this, especially within loops and conditionals, to ensure cleaner output.
Template Comments: Include comments within your templates using {# ... #}.
Testing: Make use of Jinja2 tests to perform conditional checks within your templates.

In conclusion, Jinja2 offers a compelling set of advantages for programming. Its simplicity allows for easy template creation, facilitating quick development. Jinja2's flexibility empowers developers to adapt templates to diverse use cases. It enhances code maintainability and scalability. Its syntax and adaptability make Jinja2 a valuable tool. It helps with efficient and dynamic content generation in programming projects.

Fig: Preview of the output that you will get on running this code from your IDE.

Code

In this solution we are using jinja2 library in Python.

Nested 'If' statement in jinja 'for' loop

PythonLines of Code : 42License : Strong Copyleft (CC BY-SA 4.0)

Dependent Libraries :

{% if d["current_enable_flag"] == TRUE %}
    <td> {{ON}} </td>
{% else %}
    <td> {{OFF}} </td>
{% endif %}

>>> from jinja2 import Template
>>> template = Template('''\
... {% for d in client_data %}
... <tr>
...     <td>{{ d["serial_number"]}} </td>
...     <td>{{ d["hardware_type"]}} </td>
...     {% if d["current_enable_flag"] %}
...         <td> {{ON}} </td>
...     {% else %}
...         <td> {{OFF}} </td>
...     {% endif %}
... </tr>
... {% endfor %}
... ''')
>>> html_rendered = template.render(client_data=[
...     {'serial_number': 42, 'hardware_type': 'foo', 'current_enable_flag': True},
...     {'serial_number': 81, 'hardware_type': 'bar', 'current_enable_flag': False}
... ], ON='ON', OFF='OFF')
>>> print(html_rendered)

<tr>
    <td>42 </td>
    <td>foo </td>

        <td> ON </td>

</tr>

<tr>
    <td>81 </td>
    <td>bar </td>

        <td> OFF </td>

</tr>

Instructions

Follow the steps carefully to get the output easily.

Download and Install the PyCharm Community Edition on your computer.
Open the terminal and install the required libraries with the following commands.
Create a new Python file on your IDE.
Copy the snippet using the 'copy' button and paste it into your python file.
Remove lines of code from no:1 to 5 and also from no:27 to 41 and remove ">>>" and dots "..." from remaining lines. Then save the code.
Run the current file to generate the output.

I hope you found this useful.

I found this code snippet by searching for 'How to use if else in Jinja2' in Kandi. You can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

PyCharm Community Edition 2022.3.1
The solution is created in Python 3.11.1 Version
jinja 3.1.2 Version

Using this solution, we can able to use if else in Jinja2 in python with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to use if else in Jinja2 in python.

Dependent Library

jinjaby pallets

Python

9285

Version:3.1.2

License: Permissive (BSD-3-Clause)

A very fast and expressive template engine.

Support

Quality

Security

License

Reuse

jinjaby pallets

Python 9285 Version:3.1.2 License: Permissive (BSD-3-Clause)

A very fast and expressive template engine.

Support

Quality

Security

License

Reuse

You can search for any dependent library on Kandi like 'jinja'.

FAQs

1. What are the default Jinja delimiters, and how do they work?

The default Jinja delimiters are {% ... %} for statements, {{...}} for expressions, and {# ... #} for comments. Statements control the flow of template execution, and expressions produce output. Also, it ignores the comments during rendering.

2. How can I create an HTML skeleton document using the jinja2 if else statement?

You can include or exclude parts of the HTML to create an HTML skeleton using Jinja2 with an if else.

For example:

<!DOCTYPE html>

<head>

<title> {% if condition %} Title A {% else %} Title B {% endif %} </title>

</head>

<body>

{% if condition %}

This is content for condition A.

{% else %}

This is content for condition B.

{% endif %}

</body>

</html>

3. What is the template module in Jinja, and what features does it offer?

The template module in Jinja provides a way to load templates from various sources. Those sources are like files, strings, or dictionaries. It also provides a way to manage template inheritance and configure template loading. It offers features for template inheritance and macros. It provides features for other utilities to enhance template management.

4. How can I access current template variables inside a jinja if else statement?

You can refer to the variable names to access current template variables. Access those variables that is inside a Jinja if-else statement.

For example:

{% if variable_name %}

{{ variable_name }} is true.

{% else %}

{{ variable_name }} is false.

{% endif %}

5. What kind of functions does Jinja provide to help me write my templates more efficiently?

Jinja provides various functions to enhance template writing. Some common ones include:

Filters: Change variables within the template, like {{ variable|filter_name }}.
Tests: Perform tests on variables, like {% if variable is test_name %}.
Macros: Define reusable template fragments.
Include: Include other templates.
Extends: Install template inheritance.
For Loop: Iterate over a sequence in the template.

These functions help improve code organization, readability, and reusability in Jinja templates.

Support

For any support on Kandi solution kits, please use the chat
For further learning resources, visit the Open Weaver Community learning page

See similar Kits and Libraries

Open Weaver – Develop Applications Faster with Open Source

Terms
Privacy policy

How to use if else in Jinja2

Here are some tips for creating efficient and effective code using Jinja2:

Code

Instructions

Environment Tested

Dependent Library

FAQs

Support

Open Weaver – Develop Applications Faster with Open Source

kandi

Community and Support

Company

Follow