Templates

Motivating Template Rendering

Generating HTML from within Python is not fun
It can also be cumbersome
This is because HTML escaping needs to be done manually
To avoid this issue, the Jinja2 template engine is configured automatically in Flask

Describing Template Rendering

The render_template method is used to render templates
It requires the following as arguments:
- The name of the template
- The variables passed to the template engine
The following is an example of rendering a template named hello.html:

>>> from flask import render_template

>>> @app.route('/hello/')
>>> @app.route('/hello/<name>')
>>> def hello(name=None):
...     return render_template('hello.html', name=name)

Handling Templates in Flask

First, flask looks for templates in the templates folder
If we're using a module:

FlaskApp/
├── application.py
└── templates/
    └── hello.html

If we're using a package:

FlaskApp/
└── application/
    ├── __init__.py
    └── templates/
        └── hello.html

This is an example of a Jinja2 template:

<!doctype html>
<title>Hello from Flask</title>
{% if name %}
  <h1>Hello {{ name }}!</h1>
{% else %}
  <h1>Hello, World!</h1>
{% endif %}

Inside templates, we also have access to objects:
- request
- session
- g

Benefits of Templates

Templates are especially useful if inheritance is used
Template inheritance refers to building parent-child templates
These individual templates represent pieces of a larger template
For example, we can use template inheritance to keep certain elements on each page:
- Headers
- Navigations
- Footers
- etc.
Automatic escaping is enabled
This ensures security on our sites

References

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Jinja2