Flask-YAMLI18N 0.2.0 documentation


Flask-YAMLI18N is an i18n translation support for Flask which is based on PyYAML. But, why not use gettext? Because gettext may need to install additional software (on Windows) which I don’t like.

Flask-YAMLI18N is simple and only for translating text (without timezone support). PS, this is from my personal project, so you can choose to use it or not. You can try this great extension Flask_Babel.

Note: Flask-YAMLI18N requires Python 2.6+ (uses string.format syntax).


Install the extension with one of the following commands::

$ easy_install flask-yamli18n

or alternatively if you have pip installed:

$ pip install flask-yamli18n


YAML_LOCALE_PATH Define the location folder for yml files. (default is locales)
YAML_RELOAD If reload the translation when files modified. (default is False)

How to use

In your Flask application file (e.g. hello.py):

from flask import Flask, session, request
from flask_yamli18n import YAMLI18N

app = Flask(__name__)
y18n = YAMLI18N(app)
# or later
# y18n = YAMLI18N()
# y18n.init_app(app)

t = y18n.t  # for short

# default translation files folder is 'locales'
# app.config['YAML_LOCALE_PATH'] = 'locales'

app.jinja_env.filters['t'] = t
# or if you want use it as function
# app.jinja_env.globals['_'] = t

# put lang to your session
def load_lang():
    if 'lang' not in session:
        session['lang'] = request.accept_languages.best

Example folder structure:


the blueprint_a is get from:

mod = Blueprint('blueprint_a', __name__)

def index():
    return render_template('hello.html')

suppose you have a users blueprint, then the structure is:


locales/default/en.yml example:

hello: Hello  # or 'Hello' or "Hello"
hello_world: "Hello, World!"

In your template file (e.g. hello.html):

<!doctype html>
<title>{{ 'hello'|t }}</title>
{{ 'hello_world'|t }}

The output is:

<!doctype html>
Hello, World!



Version 0.2.0

(bug fixed, released on 2018-Oct-18)

  • ignore error if text may not meet parameters requirement

Version 0.1.9

(bug fixed, released on 2018-Jan-22)

  • don’t import it to get version in setup file

Version 0.1.8

(bug fixed, released on 2017-Dec-17)

  • KeyError for kwargs

Version 0.1.7

(tiny improvement, released on 2017-Oct-27)

  • moved lang and failback to kwargs, and added args for t method.

Version 0.1.5

(tiny improvement, released on 2017-Oct-26)

  • Use io module to open the yaml files with encoding utf-8 to work in python3.

Version 0.1.4

(tiny improvement, released on 2015-Jan-23)