.. _qtut_templating:
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===================================
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08: HTML Generation With Templating
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===================================
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Most web frameworks don't embed HTML in programming code. Instead, they pass
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data into a templating system. In this step we look at the basics of using HTML
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templates in Pyramid.
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Background
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==========
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Ouch. We have been making our own ``Response`` and filling the response body
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with HTML. You usually won't embed an HTML string directly in Python, but
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instead will use a templating language.
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Pyramid doesn't mandate a particular database system, form library, and so on.
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It encourages replaceability. This applies equally to templating, which is
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fortunate: developers have strong views about template languages. As of
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Pyramid 1.5a2, Pyramid doesn't even bundle a template language!
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It does, however, have strong ties to Jinja2, Mako, and Chameleon. In this step
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we see how to add `pyramid_chameleon
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<https://github.com/Pylons/pyramid_chameleon>`_ to your project, then change
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your views to use templating.
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Objectives
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==========
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- Enable the ``pyramid_chameleon`` Pyramid add-on.
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- Generate HTML from template files.
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- Connect the templates as "renderers" for view code.
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- Change the view code to simply return data.
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Steps
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=====
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#. Let's begin by using the previous package as a starting point for a new project:
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.. code-block:: bash
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cd ..; cp -r views templating; cd templating
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#. This step depends on ``pyramid_chameleon``, so add it as a dependency in ``templating/setup.py``:
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.. literalinclude:: templating/setup.py
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:linenos:
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:emphasize-lines: 7
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#. Now we can activate the development-mode distribution:
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.. code-block:: bash
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$VENV/bin/pip install -e .
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#. We need to connect ``pyramid_chameleon`` as a renderer by making a call in the setup of ``templating/tutorial/__init__.py``:
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.. literalinclude:: templating/tutorial/__init__.py
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:linenos:
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#. Our ``templating/tutorial/views.py`` no longer has HTML in it:
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.. literalinclude:: templating/tutorial/views.py
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:linenos:
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#. Instead we have ``templating/tutorial/home.pt`` as a template:
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.. literalinclude:: templating/tutorial/home.pt
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:language: html
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#. For convenience, change ``templating/development.ini`` to reload templates automatically with ``pyramid.reload_templates``:
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.. literalinclude:: templating/development.ini
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:language: ini
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#. Our unit tests in ``templating/tutorial/tests.py`` can focus on data:
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.. literalinclude:: templating/tutorial/tests.py
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:linenos:
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#. Now run the tests:
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.. code-block:: bash
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$VENV/bin/pytest tutorial/tests.py -q
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....
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4 passed in 0.46 seconds
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#. Run your Pyramid application with:
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.. code-block:: bash
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$VENV/bin/pserve development.ini --reload
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#. Open http://localhost:6543/ and http://localhost:6543/howdy in your browser.
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Analysis
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========
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Ahh, that looks better. We have a view that is focused on Python code. Our
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``@view_config`` decorator specifies a :term:`renderer` that points to our
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template file. Our view then simply returns data which is then supplied to our
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template. Note that we used the same template for both views.
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Note the effect on testing. We can focus on having a data-oriented contract
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with our view code.
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.. seealso:: :ref:`templates_chapter`, :ref:`debugging_templates`, and
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:ref:`available_template_system_bindings`.
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