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pyramid_jinja2

Overview

:term:`pyramid_jinja2` is a set of bindings that make templates written for the :term:`Jinja2` templating system work under the :term:`Pyramid` web framework.

Installation

Install using setuptools, e.g. (within a virtualenv):

$ $VENV/bin/easy_install pyramid_jinja2

Setup

Note

If you start a project from scratch, consider using the :ref:`project template <jinja2_starter_template>` which comes with a working setup and sensible defaults.

There are multiple ways to make sure that pyramid_jinja2 is active. All are completely equivalent:

  1. Use the :py:func:`~pyramid_jinja2.includeme` function via :py:meth:`~pyramid.config.Configurator.include`:

    config = Configurator()
    config.include('pyramid_jinja2')
    
  2. Add pyramid_jinja2 to the list of your pyramid.includes in your :file:`.ini` settings file:

    pyramid.includes =
        pyramid_jinja2
    
  3. If you're using pyramid_zcml instead of imperative configuration, ensure that some ZCML file with an analogue of the following contents is executed by your Pyramid application:

    <include package="pyramid_jinja2"/>

Once activated either of these says, the following happens:

  1. Files with the :file:`.jinja2` extension are considered to be :term:`Jinja2` templates and a :class:`jinja2.Environment` is registered to handle this extension.
  2. The :func:`pyramid_jinja2.add_jinja2_renderer` directive is added to the :term:`Configurator` instance.
  3. The :func:`pyramid_jinja2.add_jinja2_search_path` directive is added to the :term:`Configurator` instance.
  4. The :func:`pyramid_jinja2.add_jinja2_extension` directive is added to the :term:`Configurator` instance.
  5. The :func:`pyramid_jinja2.get_jinja2_environment` directive is added to the :term:`Configurator` instance.

Preparing for distribution

If you want to make sure your :file:`.jinja2` template files are included in your package's source distribution (e.g. when using python setup.py sdist), add *.jinja2 to your :file:`MANIFEST.in`:

recursive-include yourapp *.ico *.png *.css *.gif *.jpg *.pt *.txt *.mak *.mako *.jinja2 *.js *.html *.xml

Usage

Once pyramid_jinja2 has been activated, :file:`.jinja2` templates can be used by the Pyramid rendering system.

When used as the renderer argument of a view, the view must return a Python dict which will be passed into the template as the set of available variables.

Template Lookup Mechanisms

There are several ways to configure pyramid_jinja2 to find your templates.

Asset Specifications

Templates may always be defined using an :term:`asset specification`. These are strings which define an absolute location of the template relative to some Python package. For example myapp.views:templates/home.jinja2. These specifications are supported throughout Pyramid and provide a fool-proof way to find any supporting assets bundled with your application.

Here's an example view configuration which uses an :term:`asset specification`:

Asset specifications have some significant benefits in Pyramid, as they are fully overridable. An addon package can ship with code that renders using asset specifications. Later another package can externally override the templates without having to actually modify the addon in any way. See :ref:`pyramid:overriding_assets_section` for more information.

Caller-Relative Template Lookup

By default, templates are discovered relative to the caller's package. This means that if you define a view in a Python module, the templates would be found relative to the module's directory on the filesystem.

Let's look at an example:

Imagine that the above code is in a myapp.admin.views module. The template would be relative to that module on the filesystem, as shown below:

myapp
|- __init__.py
`- admin
   |- views.py
   `- templates
      |- base.jinja2
      `- mytemplate.jinja2

Caller-relative lookup avoids naming collisions which can be common in a search path-based approach.

A caller-relative template lookup is converted to a :term:`asset specification` underneath the hood. This means that it's almost always possible to override the actual template in an addon package without having to fork the addon itself. For example, the full asset spec for the view above would be myapp.admin.views:templates/mytemplate.jinja2. This template, or the entire templates folder may be overridden.

config.override_asset(
    to_override='myapp.admin.views:templates/mytemplate.jinja2',
    override_with='yourapp:templates/sometemplate.jinja2')

See :ref:`pyramid:overriding_assets_section` for more information.

Search Path-Based Template Lookup

When used outside of Pyramid, Jinja2's default lookup mechanism is a search path. To use a search path within Pyramid, simply define the jinja2.directories configuration setting or use the :func:`~pyramid_jinja2.add_jinja2_search_path` configurator directive.

Rendering :term:`Jinja2` templates with a search path is typically done as follows:

@view_config(renderer='mytemplate.jinja2')
def my_view(request):
    return {'foo': 1, 'bar': 2}

If mytemplate.jinja2 is not found in the same directory as the module then it will be searched for on the search path. We are now dependent on our configuration settings to tell us where the template may be located. Commonly a templates directory is created at the base of the package and the configuration file will include the following directive:

jinja2.directories = mypkg:templates

Warning

It is possible to specify a relative path to the templates folder, such as jinja2.directories = templates. This folder will be found relative to the first package that includes pyramid_jinja2, which will normally be the root of your application. It is always better to be explicit when in doubt.

Note

The package that includes pyramid_jinja2 will always be added to the search path (in most cases this is top-level package in your application). This behavior may be deprecated or removed in the future, it is always better to specify your search path explicitly.

Templates Including Templates

:term:`Jinja2` allows :term:`template inheritance` as well as other mechanisms for templates to load each other. The lookup mechanisms supported in these cases include asset specifications, template-relative names and normal template names found on the search path. The search path will always be consulted if a template cannot be found relative to the parent template. For example if you had a template named templates/child.jinja2 that wanted to extend templates/base.jinja2 then it could use {% extends 'base.jinja2' %} and locate the file relative to itself or it could use {% extends 'templates/base.jinja2' %} to find the template in a templates subfolder rooted on the search path. The template-relative option will always override the search path.

An example:

For further information on :term:`Template Inheritance` in Jinja2 templates please see :ref:`Template Inheritance <jinja2:template-inheritance>` in Jinja2 documentation.

Adding or Overriding a Renderer

By default, only templates ending in the .jinja2 file extension are supported. However, it is very easy to add support for alternate file extensions using the :func:`pyramid_jinja2.add_jinja2_renderer` directive.

config.include('pyramid_jinja2')
config.add_jinja2_renderer('.html')

It would now be possible to use templates named foo.html and foo.jinja2. Each renderer extension will use its own :class:`jinja2.Environment`. These alternate renderers can be extended at runtime using the name parameter to the other directives such as :func:`pyramid_jinja2.get_jinja2_environment`.

config.include('pyramid_jinja2')
config.add_jinja2_renderer('.html')
config.add_jinja2_search_path('myapp:templates', name='.html')

It is also possible to setup different renderers that use different search paths, configuration settings and environments if necessary. This technique can come in handy when different defaults are required for rendering templates with different content types. For example, a plain text email body versus an html page. For this reason, :func:`pyramid_jinja2.add_jinja2_renderer` accepts an optional parameter settings_prefix which can point a renderer at a different group of settings.

settings = {
    'jinja2.directories': 'myapp:html_templates',
    'mail.jinja2.directories': 'myapp:email_templates',
}

config = Configurator(settings=settings)
config.include('pyramid_jinja2')
config.add_jinja2_renderer('.email', settings_prefix='mail.jinja2.')

Now foo.email will be rendered using the mail.jinja2.* settings.

Internalization (i18n)

When :term:`pyramid_jinja2` is included in a Pyramid application, :ref:`jinja2.ext.i18n <jinja2:i18n-extension>` is automatically activated.

Be sure to configure jinja2.i18n.domain according to setup.cfg domain settings. By default, jinja2.i18n.domain is set to the name of the package that included pyramid_jinja2. If no package was found, it will use messages.

Settings

:term:`Jinja2` derives additional settings to configure its template renderer. Many of these settings are optional and only need to be set if they should be different from the default. The below values can be present in the :file:`.ini` file used to configure the Pyramid application (in the app section representing your Pyramid app) or they can be passed directly within the settings argument passed to a Pyramid Configurator.

Generic Settings

These settings correspond to the ones documented in Jinja2. Set them accordingly.

For reference please see: http://jinja.pocoo.org/docs/api/#high-level-api

Note

For the boolean settings please use true or false

jinja2.block_start_string

jinja2.block_end_string

jinja2.variable_start_string

jinja2.variable_end_string

jinja2.comment_start_string

jinja2.comment_end_string

jinja2.line_statement_prefix

jinja2.line_comment_prefix

jinja2.trim_blocks

jinja2.newline_sequence

jinja2.optimized

jinja2.cache_size

jinja2.autoescape

Jinja2 autoescape setting.

Possible values: true or false.

Warning

By default Jinja2 sets autoescaping to False.

pyramid_jinja2 sets it to true as it is considered a good security practice in a web setting where we want to prevent XSS attacks from rendering unsanitized user-generated content. To turn off escaping on a case-by-case basis you may use the safe filter such as {{ html_blob | safe }}.

pyramid.reload_templates

For usage see :ref:`Pyramid: Automatically Reloading Templates <pyramid:reload_templates_section>`.

true or false representing whether Jinja2 templates should be reloaded when they change on disk. Useful for development to be true. This setting sets the Jinja2 auto_reload setting.

reload_templates

Warning

Deprecated as of version 1.5, use :ref:`setting_reload_templates` instead

jinja2.auto_reload

Use Pyramid :ref:`setting_reload_templates` setting.

jinja2.directories

A list of directory names or a newline-delimited string with each line representing a directory name. These locations are where Jinja2 will search for templates. Each can optionally be an absolute resource specification (e.g. package:subdirectory/).

jinja2.input_encoding

The input encoding of templates. Defaults to utf-8.

jinja2.undefined

Changes the undefined types that are used when a variable name lookup fails. If unset, defaults to :py:class:`~jinja2.Undefined` (silent ignore). Setting it to strict will trigger :py:class:`~jinja2.StrictUndefined` behavior (raising an error, this is recommended for development). Setting it to debug will trigger :py:class:`~jinja2.DebugUndefined`, which outputs debug information in some cases. See Undefined Types

jinja2.extensions

A list of extension objects or a newline-delimited set of dotted import locations where each line represents an extension. :ref:`jinja2.ext.i18n <jinja2:i18n-extension>` is automatically activated.

jinja2.i18n.domain

Pyramid domain for translations. See :term:`Translation Domain` in Pyramid documentation. Defaults to the name of the package that activated pyramid_jinja2 or if that fails it will use messages as the domain.

jinja2.filters

A dictionary mapping filter name to filter object, or a newline-delimted string with each line in the format:

name = dotted.name.to.filter

representing :ref:`Jinja2 filters <jinja2:writing-filters>`.

jinja2.globals

A dictionary mapping global name to global template object, or a newline-delimited string with each line in the format:

name = dotted.name.to.globals

representing :ref:`Jinja2 globals <jinja2:global-namespace>`

jinja2.tests

A dictionary mapping test name to test object, or a newline-delimted string with each line in the format:

name = dotted.name.to.test

representing :ref:`Jinja2 tests <jinja2:writing-tests>`.

jinja2.bytecode_caching

If set to true, a filesystem bytecode cache will be configured (in a directory determined by :ref:`setting_jinja2_byte_cache_dir`.) To configure other types of bytecode caching, jinja2.bytecode_caching may also be set directly to an instance of :class:`jinja2.BytecodeCache` (This can not be done in a paste .ini file, however, it must be done programatically.) By default, no bytecode cache is configured.

Note that configuring a filesystem bytecode cache will (not surprisiningly) generate files in the cache directory. As templates are changed, some of these will become stale, pointless wastes of disk space. You are advised to consider a clean up strategy (such as a cron job) to check for and remove such files.

See the :ref:`Jinja2 Documentation <jinja2:bytecode-cache>` for more information on bytecode caching.

jinja2.bytecode_caching_directory

Absolute path to directory to store bytecode cache files. Defaults to the system temporary directory. This is only used if jinja2.bytecode_caching is set to true.

jinja2.newstyle

true or false to enable the use of newstyle gettext calls. Defaults to false.

See Newstyle Gettext http://jinja.pocoo.org/docs/extensions/#newstyle-gettext

Jinja2 Filters

pyramid_jinja2 provides following filters.

To use these filters, configure the settings of jinja2.filters:

And use the filters in template.

<a href="{{context|model_url('edit')}}">Edit</a>

<a href="{{'top'|route_url}}">Top</a>

<link rel="stylesheet" href="{{'yourapp:static/css/style.css'|static_url}}" />

Creating a Jinja2 Pyramid Project

After you've got pyramid_jinja2 installed, you can invoke one of the following commands to create a Jinja2-based Pyramid project.

On Pyramid 1.0, 1.1, or 1.2:

$ $VENV/bin/paster create -t pyramid_jinja2_starter myproject

On Pyramid 1.3+:

$ $VENV/bin/pcreate -s pyramid_jinja2_starter myproject

After it's created, you can visit the myproject directory and run setup.py develop. At that point you can start the application like any other Pyramid application.

This is a good way to see a working Pyramid application that uses Jinja2, even if you wind up not using the result.

Paster Template I18N

The paster template automatically sets up pot/po/mo locale files for use with the generated project.

The usual pattern for working with i18n in pyramid_jinja2 is as follows:

More Information

Reporting Bugs / Development Versions

Visit http://github.com/Pylons/pyramid_jinja2 to download development or tagged versions.

Visit http://github.com/Pylons/pyramid_jinja2/issues to report bugs.

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