python - How to load jinja template directly from filesystem

Question

The jinja API document at pocoo.org states:

The simplest way to configure Jinja2 to load templates for your application looks roughly like this:

from jinja2 import Environment, PackageLoader
env = Environment(loader=PackageLoader('yourapplication', 'templates'))

This will create a template environment with the default settings and a loader that looks up the templates in the templates folder inside the yourapplication python package.

As it turns out, this isn't so simple because you have to make/install a python package with your templates in it, which introduces a lot of needless complexity, especially if you have no intention of distributing your code. You can refer to SO questions on the topic here and here, but the answers are vague and unsatisfying.

What a naive newbie wants to do, obviously, is just load the template directly from the filesystem, not as a resource in a package. How is this done?

Answer 1

Here's how: use a FileSystemLoader instead of a PackageLoader. I found examples on the web here and here. Let's say you have a python file in the same dir as your template:

./index.py
./template.html

This index.py will find the template and render it:

#!/usr/bin/python
import jinja2

templateLoader = jinja2.FileSystemLoader(searchpath="./")
templateEnv = jinja2.Environment(loader=templateLoader)
TEMPLATE_FILE = "template.html"
template = templateEnv.get_template(TEMPLATE_FILE)
outputText = template.render()  # this is where to put args to the template renderer

print(outputText)

It turns out, the jinja2 API doc does have a section which discusses all the built-in loaders, so it's kind of embarrassing not to have noticed that right away. But the introduction is worded such that PackageLoader seems to be the default, "simplest" method. For newcomers to python, this can lead to a wild goose chase.