#25839: RequestContext does not apply context processors [regression]
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Reporter: direx | Owner: nobody
Type: Bug | Status: new
Component: Template system | Version: 1.8
Severity: Release blocker | Resolution:
Keywords: RequestContext, | Triage Stage: Accepted
regression |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by carljm):
As part of the multiple-template-engines feature, Django 1.8 refactored
the Django template language to remove the direct coupling to global
settings, instead making it possible to instantiate multiple
independently-configured `Engine` instances (and configure multiple such
instances via the new `TEMPLATES` setting). Because of this, it's no
longer possible for `RequestContext` to automatically fetch the list of
configured context processors from settings (the `TEMPLATES` setting can
define multiple instances of the DTL with different lists of context
processors, so how could `RequestContext` possibly know which list of
context processors to use?). This was handled by adding a new context-
manager method `RequestContext.bind_template` which temporarily binds a
`RequestContext` to a template instance, in the process applying all the
context processors from that template's engine configuration.
This solution is fully backwards-compatible for the only documented usage
of a `RequestContext`, which is to pass it into a template render and
access its values in the template. It's true that it's not backwards-
compatible for the usage you demonstrate, directly accessing values from
the context as a dictionary without rendering a template, but this is not
a documented or supported mode of use for `RequestContext`. If you need
this usage, you must now first bind the context to a specific template:
{{{
from django.template import engines
engine = engines['default']
tpl = engine.get_template('some/template.html')
ctx = RequestContext(request)
with ctx.bind_template(tpl):
print(ctx['user'])
}}}
It may be possible to restore the old behavior for this usage using
`Engine.get_default()` (it would only work if there's only a single
instance of the DTL configured in settings); personally I don't think
that's worth doing, or that this use of `RequestContext` should be
supported.
Alternatively, we could add a warning to the 1.8 release notes about this,
but this usage is so unusual that I'm not even sure that's worth doing.
--
Ticket URL: <https://code.djangoproject.com/ticket/25839#comment:2>
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