9. Internationalization and Localization | Flask Framework Cookbook

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Flask Framework Cookbook

By : Shalabh Aggarwal

4.3 (4)

Flask Framework Cookbook

4.3 (4)

By: Shalabh Aggarwal

Overview of this book

If you are a web developer who wants to learn more about developing applications in Flask and scale them with industry-standard practices, this is the book for you. This book will also act as a handy tool if you are aware of Flask's major extensions and want to make the best use of them. It is assumed that you have knowledge of Python and a basic understanding of Flask. If you are completely new to Flask, reading the book from the first chapter and going forward will help in getting acquainted with Flask as you go ahead.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Flask Configurations

1. Flask Configurations

Introduction

Environment setup with virtualenv

Handling basic configurations

Class-based settings

Organization of static files

Being deployment specific with instance folders

Composition of views and models

Creating a modular web app with blueprints

Making a Flask app installable using setuptools

2. Templating with Jinja2

2. Templating with Jinja2

Introduction

Bootstrap layout

Block composition and layout inheritance

Creating a custom context processor

Creating a custom Jinja2 filter

Creating a custom macro for forms

Advanced date and time formatting

3. Data Modeling in Flask

3. Data Modeling in Flask

Introduction

Creating a SQLAlchemy DB instance

Creating a basic product model

Creating a relational category model

Database migration using Alembic and Flask-Migrate

Model data indexing with Redis

Opting the NoSQL way with MongoDB

4. Working with Views

4. Working with Views

Introduction

Writing function-based views and URL routes

Class-based views

URL routing and product-based pagination

Rendering to templates

Dealing with XHR requests

Decorator to handle requests beautifully

Creating custom 404 and 500 handlers

Flashing messages for better user feedback

SQL-based searching

5. Webforms with WTForms

5. Webforms with WTForms

Introduction

SQLAlchemy model data as form representation

Validating fields on the server side

Creating a common forms set

Creating custom fields and validation

Creating a custom widget

Uploading files via forms

Cross-site Request Forgery protection

6. Authenticating in Flask

6. Authenticating in Flask

Introduction

Simple session-based authentication

Authenticating using the Flask-Login extension

Using OpenID for authentication

Using Facebook for authentication

Using Google for authentication

Using Twitter for authentication

7. RESTful API Building

7. RESTful API Building

Introduction

Creating a class-based REST interface

Creating an extension-based REST interface

Creating a SQLAlchemy-independent REST API

A complete REST API example

8. Admin Interface for Flask Apps

8. Admin Interface for Flask Apps

Introduction

Creating a simple CRUD interface

Using the Flask-Admin extension

Registering models with Flask-Admin

Creating custom forms and actions

WYSIWYG for textarea integration

Creating user roles

9. Internationalization and Localization

9. Internationalization and Localization

Introduction

Adding a new language

Lazy evaluation and the gettext/ngettext functions

Global language-switching action

10. Debugging, Error Handling, and Testing

10. Debugging, Error Handling, and Testing

Introduction

Setting up basic file logging

Sending e-mails on the occurrence of errors

Using Sentry to monitor exceptions

Debugging with pdb

Creating our first simple test

Writing more tests for views and logic

Nose library integration

Using mocking to avoid real API access

Determining test coverage

Using profiling to find bottlenecks

11. Deployment and Post Deployment

11. Deployment and Post Deployment

Introduction

Deploying with Apache

Deploying with uWSGI and Nginx

Deploying with Gunicorn and Supervisor

Deploying with Tornado

Using Fabric for deployment

S3 storage for file uploads

Deploying with Heroku

Deploying with AWS Elastic Beanstalk

Application monitoring with Pingdom

Application performance management and monitoring with New Relic

12. Other Tips and Tricks

12. Other Tips and Tricks

Introduction

Full-text search with Whoosh

Full-text search with Elasticsearch

Working with signals

Using caching with your application

E-mail support for Flask applications

Understanding asynchronous operations

Working with Celery

Index

Index

Adding a new language

By default, English is the language for applications built in Flask (and almost all web frameworks). We will add a second language to our application and add some translations for the display strings used in the application. The language displayed to the user will vary depending on the current language set in the browser.

Getting ready

We will start with the installation of the Flask-Babel extension:

$ pip install Flask-Babel

This extension uses Babel, pytz, and speaklater to add i18n and l10n support to the application.

We will use our catalog application from Chapter 5, Webforms with WTForms.

How to do it…

First, we will start with the configuration part by creating an instance of the Babel class using the app object. We will also specify what languages will be available here. French is added as the second language:

from flask.ext.babel import Babel

ALLOWED_LANGUAGES = {
    'en': 'English',
    'fr': 'French',
}
babel = Babel(app)

Tip

Here, we used en and fr as the language...

Visually different images

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