published on %s
' % - entity.publish_date.strftime('%Y-%m-%d')) - super(BlogEntryPrimaryView, self).render_entity_attributes(entity) - -The above source code defines a new primary view for -``BlogEntry``. The `id` class attribute is not repeated there since it -is inherited through the `primary.PrimaryView` class. - -The selector for this view chains the selector of the inherited class -with its own specific criterion. - -The view method ``self.w()`` is used to output data. Here `lines -08-09` output HTML for the publication date of the entry. - -.. image:: ../../images/lax-book.09-new-view-blogentry.en.png - :alt: blog entries now look much nicer - -Let us now improve the primary view of a blog - -.. sourcecode:: python - - from logilab.mtconverter import xml_escape - from cubicweb.selectors import implements, one_line_rset - from cubicweb.web.views.primary import Primaryview - - class BlogPrimaryView(PrimaryView): - __regid__ = 'primary' - __select__ = PrimaryView.__select__ & implements('Blog') - rql = 'Any BE ORDERBY D DESC WHERE BE entry_of B, BE publish_date D, B eid %(b)s' - - def render_entity_relations(self, entity): - rset = self._cw.execute(self.rql, {'b' : entity.eid}) - for entry in rset.entities(): - self.w(u'%s
' % entry.view('inblogcontext')) - - class BlogEntryInBlogView(EntityView): - __regid__ = 'inblogcontext' - __select__ = implements('BlogEntry') - - def cell_call(self, row, col): - entity = self.cw_rset.get_entity(row, col) - self.w(u'%s' % - entity.absolute_url(), - xml_escape(entity.content[:50]), - xml_escape(entity.description)) - -This happens in two places. First we override the -render_entity_relations method of a Blog's primary view. Here we want -to display our blog entries in a custom way. - -At `line 10`, a simple request is made to build a result set with all -the entities linked to the current ``Blog`` entity by the relationship -``entry_of``. The part of the framework handling the request knows -about the schema and infers that such entities have to be of the -``BlogEntry`` kind and retrieves them (in the prescribed publish_date -order). - -The request returns a selection of data called a result set. Result -set objects have an .entities() method returning a generator on -requested entities (going transparently through the `ORM` layer). - -At `line 13` the view 'inblogcontext' is applied to each blog entry to -output HTML. (Note that the 'inblogcontext' view is not defined -whatsoever in *CubicWeb*. You are absolutely free to define whole view -families.) We juste arrange to wrap each blogentry output in a 'p' -html element. - -Next, we define the 'inblogcontext' view. This is NOT a primary view, -with its well-defined sections (title, metadata, attribtues, -relations/boxes). All a basic view has to define is cell_call. - -Since views are applied to result sets which can be tables of data, we -have to recover the entity from its (row,col)-coordinates (`line -20`). Then we can spit some HTML. - -But careful: all strings manipulated in *CubicWeb* are actually -unicode strings. While web browsers are usually tolerant to incoherent -encodings they are being served, we should not abuse it. Hence we have -to properly escape our data. The xml_escape() function has to be used -to safely fill (X)HTML elements from Python unicode strings. - - -**This is to be compared to interfaces and protocols in object-oriented -languages. Applying a given view called 'a_view' to all the entities -of a result set only requires to have for each entity of this result set, -an available view called 'a_view' which accepts the entity.** - -**Instead of merely using type based dispatch, we do predicate dispatch -which is quite more powerful.** - -Assuming we added entries to the blog titled `MyLife`, displaying it -now allows to read its description and all its entries. - -.. image:: ../../images/lax-book.10-blog-with-two-entries.en.png - :alt: a blog and all its entries - -**Before we move forward, remember that the selection/view principle is -at the core of *CubicWeb*. Everywhere in the engine, data is requested -using the RQL language, then HTML/XML/text/PNG is output by applying a -view to the result set returned by the query. That is where most of the -flexibility comes from.** - -[WRITE ME] - -* implementing interfaces, calendar for blog entries -* show that a calendar view can export data to ical - -We will implement the `cubicweb.interfaces.ICalendarable` interfaces on -entities.BlogEntry and apply the OneMonthCalendar and iCalendar views -to result sets like "Any E WHERE E is BlogEntry" - -* create view "blogentry table" with title, publish_date, category - -We will show that by default the view that displays -"Any E,D,C WHERE E publish_date D, E category C" is the table view. -Of course, the same can be obtained by calling -self.wview('table',rset) - -* in view blog, select blogentries and apply view "blogentry table" -* demo ajax by filtering blogentry table on category - -we did the same with 'primary', but with tables we can turn on filters -and show that ajax comes for free. -[FILLME] - - -XML views, binaries views... -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -For views generating other formats than HTML (an image generated dynamically -for example), and which can not simply be included in the HTML page generated -by the main template (see above), you have to: - -* set the attribute `templatable` of the class to `False` -* set, through the attribute `content_type` of the class, the MIME type generated - by the view to `application/octet-stream` - -For views dedicated to binary content creation (like dynamically generated -images), we have to set the attribute `binary` of the class to `True` (which -implies that `templatable == False`, so that the attribute `w` of the view could be -replaced by a binary flow instead of unicode).