How to Get the Base Url Of A Website In Jinja2?

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To get the base URL of a website in Jinja2, you can make use of the url_for function provided by Flask. Here's how you can achieve it:

  1. First, make sure you have Flask installed and a Flask application set up.
  2. In your Jinja2 template file, you can use the url_for function to generate URLs for your routes and views. To extract the base URL, you can utilize the url_for function without specifying any endpoint.


{% set base_url = url_for('_dummy')[:-7] %}

In the above code, url_for('_dummy') generates a URL for the _dummy endpoint (a non-existing one), and we remove the /dummy part from the generated URL to get the base URL.

  1. Now, you can use the base_url variable to access the base URL in your template as needed.
<h1>The base URL of this website is: {{ base_url }}</h1>

This approach works because url_for will generate URLs relative to the application's root directory, effectively giving you the base URL.

What is the purpose of getting the base URL in Jinja2?

The purpose of getting the base URL in Jinja2 is to get the root or base URL of a website in order to build or construct relative URLs. This is especially useful when creating links or references to other pages, assets (such as images or CSS files), or endpoints within the same website. By obtaining the base URL, developers can ensure that links are correctly formed, regardless of the current page's location or URL structure.

How to concatenate the base URL with a specific endpoint in Jinja2?

In Jinja2, you can concatenate the base URL with a specific endpoint using the ~ operator. Here's an example:

{% set base_url = "" %}
{% set endpoint = "/api" %}

{% set full_url = base_url ~ endpoint %}

<p>Full URL: {{ full_url }}</p>

In the above code, the ~ operator is used to concatenate the base_url and endpoint variables to create the full_url variable. The resulting full_url variable will contain the concatenated value, which in this case would be "".

You can then use the full_url variable within your template as needed.

What is the default base URL in Jinja2?

In Jinja2, the default base URL is the file system loader URL, which represents the current working directory.

How to include the base URL in a hyperlink using Jinja2?

To include the base URL in a hyperlink using Jinja2, you can use the url_for function provided by Flask. Here's an example of how to do it:

  1. In your Python file (e.g.,, pass the base URL to the Jinja2 template context:
from flask import Flask, render_template
app = Flask(__name__)

def index():
    base_url = request.host_url  # Get the base URL dynamically
    return render_template('index.html', base_url=base_url)

if __name__ == '__main__':

  1. In your Jinja2 template (e.g., index.html), you can use the url_for function along with the base_url variable to include the base URL in a hyperlink:
<a href="{{ base_url ~ url_for('route_name') }}">Link</a>

Make sure to replace 'route_name' with the actual name of the route for which you want to generate the URL.

By concatenating the base_url and the result of url_for using ~ (tilde), you can construct a full URL for your hyperlink that includes the base URL.

How to extract the base URL using Jinja2?

In Jinja2, you can extract the base URL from a given URL by using the url_parse filter. Here's an example:

  1. Import the required package:
from jinja2 import Environment, PackageLoader, select_autoescape, Markup
from urllib.parse import urljoin

  1. Create an environment and load the necessary template:
env = Environment(loader=PackageLoader('your_package', 'templates'), autoescape=select_autoescape(['html', 'xml']))

  1. Define a custom filter to extract the base URL:
def get_base_url(url):
    return urljoin(url, '/')

env.filters['get_base_url'] = get_base_url

  1. Render the template and pass the URL to the template:
template = env.get_template('your_template.html')
output = template.render(url='')

  1. In your template HTML file, use the get_base_url filter to extract the base URL:
{{ url|get_base_url }}

This will output the base URL:

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