From 6117c04a79d29b710391d95c5cce63358c5490fe Mon Sep 17 00:00:00 2001 From: Chris McDonough Date: Mon, 1 Jun 2009 00:15:14 +0000 Subject: Keep useful stuff. --- docs/tutorials/bfgwiki2/definingviews.rst | 364 ------------------------------ 1 file changed, 364 deletions(-) delete mode 100644 docs/tutorials/bfgwiki2/definingviews.rst (limited to 'docs/tutorials/bfgwiki2/definingviews.rst') diff --git a/docs/tutorials/bfgwiki2/definingviews.rst b/docs/tutorials/bfgwiki2/definingviews.rst deleted file mode 100644 index bf47c37ad..000000000 --- a/docs/tutorials/bfgwiki2/definingviews.rst +++ /dev/null @@ -1,364 +0,0 @@ -============== -Defining Views -============== - -Views in BFG are typically simple Python functions that accept two -parameters: :term:`context`, and :term:`request`. A view is assumed -to return a :term:`response` object. - -Adding View Functions -===================== - -We're going to add four :term:`view` functions to our ``views.py`` -module. One view (named ``view_wiki``) will display the wiki itself -(it will answer on the root URL), another named ``view_page`` will -display an individual page, another named ``add_page`` will allow a -page to be added, and a final view named ``edit_page`` will allow a -page to be edited. - -.. note:: - - There is nothing automagically special about the filename - ``views.py``. A project may have many views throughout its codebase - in arbitrarily-named files. Files implementing views often have - ``view`` in their filenames (or may live in a Python subpackage of - your application package named ``views``), but this is only by - convention. - - -The ``view_wiki`` view function -------------------------------- - -The ``view_wiki`` function will respond as the default view of a -``Wiki`` model object. It always redirects to the ``Page`` object -named "FrontPage". It returns an instance of the -``webob.exc.HTTPFound`` class (instances of which implement the WebOb -:term:`response` interface), and the ``repoze.bfg.model_url`` API. -``model_url`` constructs a URL to the ``FrontPage`` page -(e.g. ``http://localhost:6543/FrontPage``), and uses it as the -"location" of the HTTPFound response, forming an HTTP redirect. - -The ``view_page`` view function -------------------------------- - -The ``view_page`` function will respond as the default view of a -``Page`` object. The ``view_page`` function renders the -:term:`ReStructuredText` body of a page (stored as the ``data`` -attribute of the context, which will be a Page object) as HTML. Then -it substitutes an HTML anchor for each *WikiWord* reference in the -rendered HTML using a compiled regular expression. - -The curried function named ``check`` is used as the first argument to -``wikiwords.sub``, indicating that it should be called to provide a -value for each WikiWord match found in the content. If the wiki (our -page's ``__parent__``) already contains a page with the matched -WikiWord name, the ``check`` function generates a view link to be used -as the substitution value and returns it. If the wiki does not -already contain a page with with the matched WikiWord name, the -function generates an "add" link as the subsitution value and returns -it. - -As a result, the ``content`` variable is now a fully formed bit of -HTML containing various view and add links for WikiWords based on the -content of our current page object. - -We then generate an edit URL (because it's easier to do here than in -the template), and we call the -``repoze.bfg.chameleon_zpt.render_template_to_response`` function with -a number of arguments. The first argument is the *relative* path to a -:term:`Chameleon` ZPT template. It is relative to the directory of -the file in which we're creating the ``view_page`` function. The -``render_template_to_response`` function also accepts ``request``, -``page``, ``content``, and ``edit_url`` as keyword arguments. As a -result, the template will be able to use these names to perform -various rendering tasks. - -The result of ``render_template_to_response`` is returned to -:mod:`repoze.bfg`. Unsurprisingly, it is a response object. - -The ``add_page`` view function ------------------------------- - -The ``add_page`` function will be invoked when a user clicks on a -WikiWord which isn't yet represented as a page in the system. The -``check`` function within the ``view_page`` view generates URLs to -this view. It also acts as a handler for the form that is generated -when we want to add a page object. The ``context`` of the -``add_page`` view is always a Wiki object (*not* a Page object). - -The request :term:`subpath` in BFG is the sequence of names that are -found *after* the view name in the URL segments given to BFG as the -result of a request. If our add view is invoked via, -e.g. ``http://localhost:6543/add_page/SomeName``, the :term:`subpath` -will be ``['SomeName']``. - -The add view takes the zeroth element of the subpath (the wiki page -name), and aliases it to the name attribute in order to know the name -of the page we're trying to add. - -If the view rendering is *not* a result of a form submission (if the -expression ``'form.submitted' in request.params`` is False), the view -renders a template. To do so, it generates a "save url" which the -template use as the form post URL during rendering. We're lazy here, -so we're trying to use the same template (``templates/edit.pt``) for -the add view as well as the page edit view, so we create a dummy Page -object in order to satisfy the edit form's desire to have *some* page -object exposed as ``page``, and we'll render the template to a -response. - -If the view rendering *is* a result of a form submission (if the -expression ``'form.submitted' in request.params`` is True), we scrape -the page body from the form data, create a Page object using the name -in the subpath and the page body, and save it into "our context" (the -wiki) using the ``__setitem__`` method of the context. We then -redirect back to the ``view_page`` view (the default view for a page) -for the newly created page. - -The ``edit_page`` view function -------------------------------- - -The ``edit_page`` function will be invoked when a user clicks the -"Edit this Page" button on the view form. It renders an edit form but -it also acts as the handler for the form it renders. The ``context`` -of the ``edit_page`` view will *always* be a Page object (never a Wiki -object). - -If the view rendering is *not* a result of a form submission (if the -expression ``'form.submitted' in request.params`` is False), the view -simply renders the edit form, passing the request, the page object, -and a save_url which will be used as the action of the generated form. - -If the view rendering *is* a result of a form submission (if the -expression ``'form.submitted' in request.params`` is True), the view -grabs the ``body`` element of the request parameter and sets it as the -``data`` attribute of the page context. It then redirects to the -default view of the context (the page), which will always be the -``view_page`` view. - -Viewing the Result of Our Edits to ``views.py`` -=============================================== - -The result of all of our edits to ``views.py`` will leave it looking -like this: - -.. literalinclude:: src/views/tutorial/views.py - :linenos: - :language: python - -Adding Templates -================ - -The views we've added all reference a :term:`template`. Each template -is a :term:`Chameleon` template. The default templating system in -:mod:`repoze.bfg` is a variant of :term:`ZPT` provided by Chameleon. -These templates will live in the ``templates`` directory of our -tutorial package. - -The ``view.pt`` Template ------------------------- - -The ``view.pt`` template is used for viewing a single wiki page. It -is used by the ``view_page`` view function. It should have a div that -is "structure replaced" with the ``content`` value provided by the -view. It should also have a link on the rendered page that points at -the "edit" URL (the URL which invokes the ``edit_page`` view for the -page being viewed). - -Once we're done with the ``view.pt`` template, it will look a lot like -the below: - -.. literalinclude:: src/views/tutorial/templates/view.pt - :linenos: - :language: xml - - -The ``edit.pt`` Template ------------------------- - -The ``edit.pt`` template is used for adding and editing a wiki page. -It is used by the ``add_page`` and ``edit_page`` view functions. It -should display a page containing a form that POSTs back to the -"save_url" argument supplied by the view. The form should have a -"body" textarea field (the page data), and a submit button that has -the name "form.submitted". The textarea in the form should be filled -with any existing page data when it is rendered. - -Once we're done with the ``edit.pt`` template, it will look a lot like -the below: - -.. literalinclude:: src/views/tutorial/templates/edit.pt - :linenos: - :language: xml - -Static Resources ----------------- - -Our templates name a single static resource named ``style.css``. We -need to create this and place it in a file named ``style.css`` within -our package's ``templates/static`` directory: - -.. literalinclude:: src/views/tutorial/templates/static/style.css - :linenos: - :language: css - -This CSS file will be accessed via -e.g. ``http://localhost:6543/static/style.css`` by virtue of the -``static_view`` view we've defined in the ``views.py`` file. Any -number and type of static resources can be placed in this directory -(or subdirectories) and are just referred to by URL within templates. - -Testing the Views -================= - -We'll modify our ``tests.py`` file, adding tests for each view -function we added above. As a result, we'll *delete* the -``ViewTests`` test in the file, and add four other test classes: -``ViewWikiTests``, ``ViewPageTests``, ``AddPageTests``, and -``EditPageTests``. These test the ``view_wiki``, ``view_page``, -``add_page``, and ``edit_page`` views respectively. - -Once we're done with the ``tests.py`` module, it will look a lot like -the below: - -.. literalinclude:: src/views/tutorial/tests.py - :linenos: - :language: python - -Running the Tests -================= - -We can run these tests by using ``setup.py test`` in the same way we -did in :ref:`running_tests`. Assuming our shell's current working -directory is the "tutorial" distribution directory: - -On UNIX: - -.. code-block:: bash - - $ ../bin/python setup.py test -q - -On Windows: - -.. code-block:: bash - - - c:\bigfntut\tutorial> ..\Scripts\python setup.py test -q - -The expected result looks something like: - -.. code-block:: bash - - ......... - ---------------------------------------------------------------------- - Ran 9 tests in 0.203s - - OK - -Mapping Views to URLs in ``configure.zcml`` -=========================================== - -The ``configure.zcml`` file contains ``view`` declarations which serve -to map URLs (via :term:`traversal`) to view functions. You'll need to -add five ``view`` declarations to ``configure.zcml``. - -#. Add a declaration which maps the "Wiki" class in our ``models.py`` - file to the view named ``static_view`` in our ``views.py`` file with - the view name ``static``. - -#. Add a declaration which maps the "Wiki" class in our ``models.py`` - file to the view named ``view_wiki`` in our ``views.py`` file with - no view name. This is the default view for a Wiki. - -#. Add a declaration which maps the "Page" class in our ``models.py`` - file to the view named ``view_page`` in our ``views.py`` file with - no view name. This is the default view for a Page. - -#. Add a declaration which maps the "Wiki" class in our ``models.py`` - file to the view named ``add_page`` in our ``views.py`` file with - the view name ``add_page``. This is the add view for a new Page. - -#. Add a declaration which maps the "Page" class in our ``models.py`` - file to the view named ``edit_page`` in our ``views.py`` file with - the view name ``edit_page``. This is the edit view for a page. - -As a result of our edits, the ``configure.zcml`` file should look -something like so: - -.. literalinclude:: src/views/tutorial/configure.zcml - :linenos: - :language: xml - -Examining ``tutorial.ini`` -========================== - -Let's take a look at our ``tutorial.ini`` file. The contents of the -file are as follows: - -.. literalinclude:: src/models/tutorial.ini - :linenos: - :language: ini - -The WSGI Pipeline ------------------ - -Within ``tutorial.ini``, note the existence of a ``[pipeline:main]`` -section which specifies our WSGI pipeline. This "pipeline" will be -served up as our WSGI application. As far as the WSGI server is -concerned the pipeline *is* our application. Simpler configurations -don't use a pipeline: instead they expose a single WSGI application as -"main". Our setup is more complicated, so we use a pipeline. - -"egg:repoze.zodbconn#closer" is at the "top" of the pipeline. This is -a piece of middleware which closes the ZODB connection opened by the -PersistentApplicationFinder at the end of the request. - -"egg:repoze.tm#tm" is the second piece of middleware in the pipeline. -This commits a transaction near the end of the request unless there's -an exception raised. - -Adding an Element to the Pipeline ---------------------------------- - -Let's add a piece of middleware to the WSGI pipeline. -"egg:Paste#evalerror" middleware which displays debuggable errors in -the browser while you're developing (not recommeded for deployment). -Let's insert evalerror into the pipeline right below -"egg:repoze.zodbconn#closer", making our resulting ``tutorial.ini`` -file look like so: - -.. literalinclude:: src/views/tutorial.ini - :linenos: - :language: ini - -Viewing the Application in a Browser -==================================== - -Once we've set up the WSGI pipeline properly, we can finally examine -our application in a browser. The views we'll try are as follows: - -- Visiting `http://localhost:6543/ `_ in a - browser invokes the ``view_wiki`` view. This always redirects to - the ``view_page`` view of the FrontPage page object. - -- Visiting `http://localhost:6543/FrontPage/ - `_ in a browser invokes the - ``view_page`` view of the front page page object. This is because - it's the *default view* (a view without a ``name``) for Page objects. - -- Visiting `http://localhost:6543/FrontPage/edit_page - `_ in a browser invokes - the edit view for the front page object. - -- Visiting `http://localhost:6543/add_page/SomePageName - `_ in a browser invokes - the add view for a page. - -- To generate an error, do `http://localhost:6543/add_page - `_. IndexError for - ``request.subpath[0]``. You'll see an interactive traceback - facility provided by evalerror. - - - - - -- cgit v1.2.3