Jinja Integration

Jinja2 is one of the most popular templating engines for Python, and is packaged with Flask. Flask-Philo provides a number of additional methods to facilitate common calls to the Jinja2 engine

• init_jinja2() - A single initialisation function to bootstrap the core Jinja2 components
• get_manager() - Creates an instance of Flask-Philo’s TemplatesManage class, facilitating multiple template loaders
• set_request() - append a request object to an Environment’s global objects
• get_autoescaping_params() - fetch a custom set of AutoEscaping rules from the Flask-Philo configuration file
• load_extensions_from_config() - Specify a custom set of Jinja2 extensions from our application’s configuration file
• init_filesystem_loader() - Configures the Jinja2 FileSystemLoader with paths and parameters specified in our Flask-Philo configuration file

init_jinja2

Single initialisation function that uses Flask-Philo’s app configuration file (/src/config/development.py) to bootstrap the following Jinja2 components:

• Filesystem Loader
• Template Loader
• Autoescaping
• Extensions

config/development.py :

JINJA2_TEMPLATES = {
    'DEFAULT': {
        'LOADER': 'FileSystemLoader',
        'PARAMETERS': {
            'path': (
                os.path.join(BASE_DIR, '../', '_templates'),
            ),
            'encoding': 'utf-8',
            'followlinks': False
        },
        'AUTOESCAPING': {
            'enabled_extensions': ('html', 'htm', 'xml'),
            'disabled_extensions': [],
            'default_for_string': True,
            'default': False
        },
        'EXTENSIONS': (
            'tests.test_app.templatetags.TestExtension',
        )
    }
}

Example Python code :

from flask_philo import app
from flask import g

init_jinja2(g, app)
assert hasattr(app, 'jinja_env')
assert hasattr(app, 'jinja_options')
assert hasattr(app, 'jinja_loader')
assert hasattr(app, 'jinja_environment')

get_manager

Creates an instance of Flask-Philo’s TemplatesManager class, facilitating multiple template loaders

get_manager()

Example Python calling code :

from flask_philo.jinja2 import get_manager

# instantiate manager, and render html from template
manager = get_manager()
env = manager.environments['DEFAULT']
template = env.get_template('home.html')
output_html = template.render()

set_request

Jinja2 uses a central object called the template Environment. Instances of this class are used to store the configuration and global objects, and are used to load templates from the file system or other locations.

To append a request object to an Environment’s global objects, use the set_request() method

Example Python calling code :

from flask_philo import app
from flask_philo.jinja2 import get_manager

manager = get_manager()
ctx = app.test_request_context('/hello-template')
manager.set_request(ctx.request)
env = manager.environments['DEFAULT']

get_autoescaping_params

Flask-Philo allows us to specify a custom set of AutoEscaping rules in our application’s configuration file (e.g. /src/config/development.py). These AutoEscaping rules may then used as part of our Environment instance

config/development.py :

JINJA2_TEMPLATES = {
    'DEFAULT': {
        'AUTOESCAPING': {
            'enabled_extensions': ('html', 'htm', 'xml'),
            'disabled_extensions': [],
            'default_for_string': True,
            'default': False
        }
    }
}

Example Python code :

from flask_philo.jinja2 import get_autoescaping_params

params = get_autoescaping_params(**app.config)
env = Environment(
    autoescape=select_autoescape(**params),
)

load_extensions_from_config

Flask-Philo allows us to specify a custom set of Jinja2 extensions in our application’s configuration file (e.g. /src/config/development.py). These extensions are then used to instantiate of our Environment instance

For more detail on Jinja2 extensions, refer to the extensions documentation

config/development.py :

JINJA2_TEMPLATES = {
    'DEFAULT': {
        'EXTENSIONS': (
                'tests.test_app.templatetags.TestExtension',
            )
    }
}

Example Python code :

from flask_philo import app

env_extensions = load_extensions_from_config(app.config)
env = Environment(
    extensions=load_extensions_from_config(**env_extensions)
)

init_filesystem_loader

Configures the Jinja2 FileSystemLoader (docs here) with paths and parameters specified in our Flask-Philo configuration file /src/config/development.py Also instantiates and returns a Jinja2 Environment based on this configuration.

config/development.py :

JINJA2_TEMPLATES = {
    'DEFAULT': {
        'LOADER': 'FileSystemLoader',
        'PARAMETERS': {
            'path': (
                os.path.join(BASE_DIR, '../', '_templates'),
            ),
            'encoding': 'utf-8',
            'followlinks': False
        },
    }
}

Example Python code :

from flask_philo import app

config = app.config['JINJA2_TEMPLATES']['DEFAULT']
env = init_filesystem_loader(**config)
template = env.get_template('home.html')
txt = template.render()
assert 'random_msg hello world!!!' == txt