aiohttp-jinja2

Context processors allow you to inject variables into every template context. Unlike global variables, context processors can calculate values based on the current request (e.g., the current user).

Note: Context processors follow a 'last-win' strategy, meaning later processors can overwrite variables from earlier ones. aiohttp_jinja2 provides a built-in request_processor which adds the current aiohttp.web.Request object to the template context under the name 'request'.

# Define a processor
async def foo_processor(request):
    return {'foo': 'bar'}

# Register it during setup
aiohttp_jinja2.setup(
    app,
    context_processors=[foo_processor, aiohttp_jinja2.request_processor],
    loader=loader)

To use aiohttp-jinja2, you must first initialize the Jinja2 environment within your aiohttp.web.Application using aiohttp_jinja2.setup(). You typically provide a loader (such as jinja2.FileSystemLoader) to specify where your templates are located.

app = web.Application()
aiohttp_jinja2.setup(app,
    loader=jinja2.FileSystemLoader('/path/to/templates/folder'))

The most convenient way to render templates is by using the @aiohttp_jinja2.template decorator on your web handlers. When a decorated handler returns a dictionary, that dictionary is automatically passed as the template context.

# Function-based handler
@aiohttp_jinja2.template('tmpl.jinja2')
def handler(request):
    return {'name': 'Andrew', 'surname': 'Svetlov'}

# Class-based view
class Handler(web.View):
    @aiohttp_jinja2.template('tmpl.jinja2')
    async def get(self):
        return {'name': 'Andrew', 'surname': 'Svetlov'}

Install the library using pip:

$ pip install aiohttp-jinja2

Before rendering templates, you must initialize the Jinja2 environment within your aiohttp.web.Application instance using aiohttp_jinja2.setup(). You typically provide a loader (such as jinja2.FileSystemLoader) to specify where your template files are located.

import aiohttp_jinja2
import jinja2
from aiohttp import web

app = web.Application()
aiohttp_jinja2.setup(app, loader=jinja2.FileSystemLoader('/path/to/templates/folder'))

Install the package from PyPI using pip:

pip install aiohttp-jinja2

The most convenient way to render templates is by using the @aiohttp_jinja2.template decorator on your web handlers. When the handler returns a dictionary, the decorator automatically passes that dictionary as the template context and returns the rendered response.

Function-based handlers

@aiohttp_jinja2.template('tmpl.jinja2')
def handler(request):
    return {'name': 'Andrew', 'surname': 'Svetlov'}

Class-based views

class Handler(web.View):
    @aiohttp_jinja2.template('tmpl.jinja2')
    async def get(self):
        return {'name': 'Andrew', 'surname': 'Svetlov'}

If you need to render a template within a view function manually, use aiohttp_jinja2.render_template(). This function returns a response object.

Parameters:

• template_name: The name of the template to render.
• request: The current aiohttp.web.Request object.
• context: A dictionary of variables to pass to the template.
• app_key: The key to access the environment (defaults to 'aiohttp_jinja2_environment').
• encoding: The response charset (defaults to 'utf-8').
• status: The HTTP status code (defaults to 200).

import aiohttp_jinja2

async def handler(request):
    context = {'foo': 'bar'}
    response = aiohttp_jinja2.render_template('tmpl.jinja2', request, context)
    return response

app.router.add_get('/tmpl', handler)

Use aiohttp_jinja2.render_string() to render a raw template string and return the resulting string.

Parameters:

• template_name: The template string to render.
• request: The aiohttp.web.Request object.
• context: The dictionary used as template context.
• app_key: The key to access the environment (defaults to 'aiohttp_jinja2_environment').

Note: If enable_async=True was passed to setup(), you should use render_string_async() instead.

If you need to add global functions or modify the Jinja2 environment (e.g., adding a zip function), use aiohttp_jinja2.get_env(app) to retrieve the environment object.

env = aiohttp_jinja2.get_env(app)
env.globals.update(zip=zip)

The @aiohttp_jinja2.template decorator can be applied to both synchronous and asynchronous view functions. Instead of returning a response object, the decorated function should return a dictionary representing the template context. The decorator then handles rendering the specified template and returning the response.

Parameters:

• template_name: The name of the template file (raises 500 if not found).
• app_key: The key to access the environment from the application (defaults to 'aiohttp_jinja2_environment').
• encoding: The charset for the response (defaults to 'utf-8').
• status: The HTTP status code for the response (defaults to 200).

import aiohttp_jinja2

@aiohttp_jinja2.template('tmpl.jinja2')
async def handler(request):
    context = {'foo': 'bar'}
    return context

app.router.add_get('/tmpl', handler)

If you pass enable_async=True to the setup function, you must use the asynchronous rendering function render_template_async. The @aiohttp_jinja2.template decorator remains compatible with both sync and async modes.

aiohttp_jinja2.setup(app, enable_async=True, loader=loader)

async def handler(request):
    return await aiohttp_jinja2.render_template_async('tmpl.jinja2', request)