Is it YAML?

About

"Is it YAML?" is a Django application (with tags) for checking whether text is YAML - "a human friendly data serialization standard for all programming languages" - or not.

Users type or paste text, then click the "Submit" button. If valid YAML has been entered, the input is shown in canonical form; otherwise, the application presents an error message.

Installation and Dependencies

"Is it YAML?" depends on Django (≥ 5.2) and PyYAML (≥ 6.0). Installation is as simple as:

pip install isityaml

Setting up

Once installed, add "isityaml" to your INSTALLED_APPS list in settings.py, and include the app URLs under any path prefix you like:

# project urls.py
from django.urls import include, path

urlpatterns = [
    # ... existing routes ...
    path("this_is_the_path_to_isityaml/", include("isityaml.urls")),
]

Creating your own YAML checker page

A YAML checker can be as simple as this Django template file:

{% extends "base.html" %}
{% load isityaml_tags %}
{% block main %}
{% isityaml_checker %}
{% endblock %}

Then you can visit the URL where you mounted the app, such as /this_is_the_path_to_isityaml/. Paste or type YAML into the text area and click Submit. Valid input is shown in canonical form; invalid input shows the parser error and the original text.

Embedding in another template

Alternately, you can add this to any page with CSRF support:

{% load isityaml_tags %}
{% isityaml_checker %}

By default, the form’s action is {% url "isityaml:index" %}, which resolves to the "this_is_the_path_to_isityaml/" which you included with isityaml.urls. After submission, the user lands on a checker page with the results. To post somewhere else, you can pass an override:

{% isityaml_checker action_url="/tools/yaml-check/" %}

Text customisation

There are a lot of user interface strings, such as headings, labels and button text, which live in isityaml.copy.DEFAULT_COPY. You can change them in your settings:

# settings.py
ISITYAML_COPY = {
    "textarea_default": "Xin chào thế giới!", # Hello world! in Vietnamese
    # ...
}

Or you can provide them as arguments on the tag:

{% isityaml_checker textarea_default="Xin chào thế giới!" %}

Calling the app from Python

You can even call the application using isityaml.yaml_check:

from isityaml.yaml_check import check_yaml, STATE_POST_YES, STATE_POST_NO

result = check_yaml("foo: bar")
if result.yamlstate == STATE_POST_YES:
    print(result.yamlcanon)   # canonical YAML
elif result.yamlstate == STATE_POST_NO:
    print(result.yamlerror)
    print(result.yamloriginal)

Testing

From the package root (with the package importable, e.g. after pip install -e .):

PYTHONPATH=. python -m unittest discover -s tests -v

History

• 0.1 (August 30th 2011) - Create setup script for files.
• 0.2 (April 25th 2013) - Try to make a half-decent PyPI package.
• 0.3 (January 30th 2014) - Updated to be compatible with Django 1.6 and Mezzanine 3.0.
• 0.4 (February 15th 2014) - Added more error handling and styling to be compatible with Bootstrap.
• 0.5 (August 13th 2014) - Cleaned up error handling and installation issues.
• 0.6 (February 28th 2017) - Updated to be compatible with Django 1.10.
• 0.7 (December 6th 2020) - Run through 2to3 for Python 3 changes.
• 0.8 (September 11th 2026) - Modularise the code; clean up the changes.

Copyright

The isityaml app is copyright (c) 2009-2026 Peter Murphy peterkmurphy@gmail.com.