django-shouty-templates
| Author: | Keryn Knight |
|---|---|
| Version: | 0.1.6 |
Brief
This app applies a monkeypatch which forces Django's template language to error very loudly about variables which are used in a template but don't exist in the context.
Rationale
Given a template like this:
<html><head></head>
<body>
{% if chef.can_add_cakes %}
<label class="alert alert-{{ chef.is_cake_chef|yesno:"success,danger,default" }}
{% endif %}
everything works fine, until you refactor and any of the following happens:
-
chefis no longer the name of the variable. -
can_add_cakesis refactored to be calledcan_add_pastries -
is_cake_chefis renamedis_pastry_king
If those happen, the template will either silently display nothing, or will display the label incorrectly. This monkeypatch attempts to fix that.
Specifically:
-
chefwill raise an exception if the variable were calledsous_chef -
chef.can_add_cakeswill raise an exception ifcan_add_cakeswas no longer a valid attribute/property/method ofchef -
chef.is_cake_chefwill raise an exception for the same reasons.
Thus you can refactor somewhat more freely, knowing that if the template renders it's OK. It ain't compile time safety, but it's better than silently swallowing errors because you forgot something!
The exception itself would look something like:
Token 'chef' of 'chef.can_add_cakes' in template 'my/cool/template.html' does not resolve. Possibly you meant to use 'sous_chef'. Silence this occurance only by adding 'chef.can_add_cakes': ['my/cool/template.html'] to the settings.SHOUTY_VARIABLE_BLACKLIST dictionary. Silence this globally by adding 'chef.can_add_cakes': ['*'] to the settings.SHOUTY_VARIABLE_BLACKLIST dictionary.
Setup
This package is available on PyPI and can be installed using pip or whatever like so:
pip install django-shouty-templates==0.1.6
Then add shouty.Shout or shouty to your settings.INSTALLED_APPS
Optional configuration
A list of values which may be set in your project's settings module:
settings.SHOUTY_VARIABLES
May be True|False and determines if the exception is raised when trying to
use a variable which doesn't exist.
Defaults to True.
settings.SHOUTY_URLS
May be True|False and determines if an exception is raised when
doing {% url 'myurl' as my_var %} and myurl doesn't actually resolve to a view.
Defaults to True.
settings.SHOUTY_VARIABLE_BLACKLIST
Useful for if you are trying to fix up an existing project, or ignore problems in third-party templates.
Expects a dict of str keys and a sequence (eg: tuple or list) of templates in which to ignore it:
SHOUTY_VARIABLE_BLACKLIST = {
"chef.can_add_cakes": ("*",),
"my_sometimes_set_variable": ["admin/custom_view.html", "admin/custom_view_detail.html"],
"random_in_memory_template": ["<unknown source>"],
"*": ["admin/login.html", "<unknown source>"],
}
Of special note is the use of *, which has a more magical meaning.
- Using
"key": ["*"]would silence errors about the variable namedkeyin all templates - Using
"*": ["path/to/template.html"]would silence all variable errors in that specific template only (see GitHub issue 6)
And also the far less frequently useful <unknown source> or django.template.base.UNKNOWN_SOURCE which is essentially usually for Template instances
not loaded from a file on disk
settings.SHOUTY_URL_BLACKLIST
A tuple of 2-tuple to prevent certain URLs and their output variables f
rom shouting at you loudly. Useful for existing projects or third-party apps which are less strict.
By way of example, {% url "myurl" as my_var %} may be suppressed with:
SHOUTY_URL_BLACKLIST = (
('myurl', 'my_var'),
)
which would still let {% url "myurl" as "my_other_var" %} raise an exception.
Default configuration
There's a hard-coded blacklist of variables and URLs to make sure the Django admin (+ admindocs), django-debug-toolbar, django-pipeline, django-admin-honeypot, djangorestframework, etc all work.
if/elif/else testing
When an {% if x %} statement is seen in the template, all conditions are checked
to ensure the context will always resolve correctly. Additionally, if you use {% if %}
and {% elif %} together and don't have an {% else %} it'll raise an error
to remind you to handle that case, even if handling it is just to output nothing.
Tests
Just run python3 -m shouty and hope for the best. I usually do.
The license
It's FreeBSD. There's should be a LICENSE file in the root of the repository, and in any archives.
