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218 lines
8.1 KiB
Plaintext
218 lines
8.1 KiB
Plaintext
=================================
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Upgrading templates to Django 1.8
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=================================
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Django's template system was overhauled in Django 1.8 when it gained support
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for multiple template engines. This document complements the :doc:`release
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notes </releases/1.8>` with detailed upgrade instructions on some topics.
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The :setting:`TEMPLATES` settings
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=================================
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A new setting was introduced in Django 1.8: :setting:`TEMPLATES`. All existing
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template-related settings were deprecated.
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During the deprecation period, Django will create a backwards-compatible
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:setting:`TEMPLATES` based on the ``TEMPLATE_*`` settings if you don't define
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it yourself.
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Here's how to define :setting:`TEMPLATES` in your settings module.
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If you're using the default value of ``TEMPLATE_LOADERS``, that is, if it
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isn't defined in your settings file or if it's set to::
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('django.template.loaders.filesystem.Loader',
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'django.template.loaders.app_directories.Loader')
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then you should define :setting:`TEMPLATES` as follows::
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TEMPLATES = [
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{
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'BACKEND': 'django.template.backends.django.DjangoTemplates',
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'DIRS': [
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# insert your TEMPLATE_DIRS here
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],
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'APP_DIRS': True,
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'OPTIONS': {
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'context_processors': [
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# Insert your TEMPLATE_CONTEXT_PROCESSORS here or use this
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# list if you haven't customized them:
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'django.contrib.auth.context_processors.auth',
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'django.template.context_processors.debug',
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'django.template.context_processors.i18n',
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'django.template.context_processors.media',
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'django.template.context_processors.static',
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'django.template.context_processors.tz',
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'django.contrib.messages.context_processors.messages',
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],
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},
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},
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]
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If you aren't using the default value of ``TEMPLATE_LOADERS``, then you should
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define :setting:`TEMPLATES` as follows::
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TEMPLATES = [
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{
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'BACKEND': 'django.template.backends.django.DjangoTemplates',
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'DIRS': [
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# insert your TEMPLATE_DIRS here
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],
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'OPTIONS': {
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'context_processors': [
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# Insert your TEMPLATE_CONTEXT_PROCESSORS here or use this
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# list if you haven't customized them:
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'django.contrib.auth.context_processors.auth',
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'django.template.context_processors.debug',
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'django.template.context_processors.i18n',
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'django.template.context_processors.media',
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'django.template.context_processors.static',
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'django.template.context_processors.tz',
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'django.contrib.messages.context_processors.messages',
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],
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'loaders': [
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# insert your TEMPLATE_LOADERS here
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]
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},
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},
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]
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Furthermore you should replace ``django.core.context_processors`` with
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``django.template.context_processors`` in the names of context processors.
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If your settings module defines ``ALLOWED_INCLUDE_ROOTS`` or
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``TEMPLATE_STRING_IF_INVALID``, include their values under the
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``'allowed_include_roots'`` and ``'string_if_invalid'`` keys in the
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``'OPTIONS'`` dictionary.
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If it sets ``TEMPLATE_DEBUG`` to a value that differs from :setting:`DEBUG`,
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include that value under the ``'debug'`` key in ``'OPTIONS'``.
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Once you have defined :setting:`TEMPLATES`, you can safely remove
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``ALLOWED_INCLUDE_ROOTS``, ``TEMPLATE_CONTEXT_PROCESSORS``,
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``TEMPLATE_DEBUG``, ``TEMPLATE_DIRS``, ``TEMPLATE_LOADERS``, and
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``TEMPLATE_STRING_IF_INVALID``.
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If you are overriding some of these settings in tests, you should override the
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entire :setting:`TEMPLATES` setting instead.
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:mod:`django.template.loader`
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=============================
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.. _get_template-upgrade-django-18:
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:func:`~django.template.loader.get_template` and :func:`~django.template.loader.select_template`
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------------------------------------------------------------------------------------------------
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In Django 1.8 :func:`~django.template.loader.get_template` and
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:func:`~django.template.loader.select_template` return a backend-dependent
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``Template`` instead of a :class:`django.template.Template`.
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For example, if :func:`~django.template.loader.get_template` loads a template
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with a :class:`~django.template.backends.django.DjangoTemplates` backend, then
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it returns a ``django.template.backends.django.Template``.
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``Template`` objects must provide a
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:meth:`~django.template.backends.base.Template.render` method whose signature
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differs slightly from the Django template language's
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:meth:`~django.template.Template.render`.
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Instead of::
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from django.template import Context
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from django.template.loader import get_template
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template = get_template('hello.html')
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html = template.render(Context({'name': 'world'}))
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You should write::
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from django.template.loader import get_template
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template = get_template('hello.html')
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html = template.render({'name': 'world'})
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And instead of::
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from django.template import RequestContext
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from django.template.loader import get_template
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template = get_template('hello.html')
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html = template.render(RequestContext(request, {'name': 'world'}))
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You should write::
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from django.template.loader import get_template
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template = get_template('hello.html')
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html = template.render({'name': 'world'}, request)
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Passing a :class:`~django.template.Context` or a
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:class:`~django.template.RequestContext` is still possible when the template
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is loaded by a :class:`~django.template.backends.django.DjangoTemplates`
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backend but it's deprecated and won't be supported in Django 2.0.
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If you're loading a template while you're rendering another template with the
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Django template language and you have access to the current context, for
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instance in the ``render()`` method of a template tag, you can use the current
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:class:`~django.template.Engine` directly. Instead of::
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from django.template.loader import get_template
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template = get_template('included.html')
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You can write::
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template = context.engine.get_template('included.html')
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This will load the template with the current engine without triggering the
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multiple template engines machinery, which is usually the desired behavior.
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Unlike previous solutions, this returns a :class:`django.template.Template`,
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like :func:`~django.template.loader.get_template` used to in Django 1.7 and
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earlier, avoiding all backwards-compatibility problems.
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``get_template_from_string()``
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------------------------------
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Private API ``get_template_from_string(template_code)`` was removed in Django
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1.8 because it had no way to choose an engine to compile the template.
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Three alternatives are available.
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If you control the project's setting, you can use one of the configured
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engines::
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from django.template import engines
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template = engines['django'].from_string(template_code)
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This returns a backend-dependent ``Template`` object.
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For trivial templates that don't need context processors nor anything else,
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you can create a bare-bones engine and use its ``from_string()`` method::
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from django.template import Engine
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template = Engine().from_string(template_code)
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This returns a :class:`django.template.Template` because
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:class:`~django.template.Engine` is part of the Django template language's
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APIs. The multiple template engines machinery isn't involved here.
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Finally, if you have access to the current context, you can use the same trick
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as above::
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template = context.engine.from_string(template_code)
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``Template()``
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==============
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To a lesser extent, instantiating a template with ``Template(template_code)``
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suffers from the same issue as ``get_template_from_string()``.
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It still works when the :setting:`TEMPLATES` setting defines exactly one
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:class:`~django.template.backends.django.DjangoTemplates` backend, but
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pluggable applications can't control this requirement.
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The last two solutions described in the previous section are recommended in
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that case.
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