Where C<classmetadata.table> will actually be the name of the current
table, and C<config.base_url> will be replaced by the appropriate URL for
-this application. But where do these values, C<config> and C<classmetadata>,
-come from, and what else can we do with them?
+this application.
-=head2 What Maypole provides to a template
-
-XXX
-
-=head2 Maypole::View::TT and other view classes
+=head2 Locating Templates
-Please note that these template variables, C<config>, C<classmetadata>,
-C<objects> and its user-friendly alias, as well as the rest of themm are
-a function of one particular view class, the default
-C<Maypole::View::TT> class. Other view classes may need to present an
-entirely different set of template variables, since the default ones
-might not make sense. The templates may look wildly different in other
-view class implementations. But that's OK, because you couldn't
-necessarily use the same templates with a different templating system
-anyway.
-
-For instance, in really dumb templating languages which can't handle
-dereferencing hashes or arrays - no wait, that's most of them - passing
-in a hash reference like C<classmetadata> won't help you since you can't
-get at any of its elements. So you'll need to take a look at the
-documentation for the appropriate view class to see what template
-variables it provides.
-
-Another feture of C<Maypole::View::TT> which may not be present in
+Another feature of C<Maypole::View::TT> which may not be present in
alternate view class implementations - although they are strongly
encouraged to provide it - is the way that templates are located.
(Remember, I B<did> say I'd tell you about that later.) Template Toolkit
of F<basket/list>, F<basket/view>, F<product/list>, F<product/view>
and any other combination of classes and actions that you can think of.
-Again, this only goes for C<Maypole::View::TT>. If, for some perverse
-reason, the Template Toolkit just isn't good enough for you, then you
-can set your own view class while configuring your application:
+=head2 What Maypole provides to a template
+
+C<Maypole::View::TT> provides quite a variety of template variables to
+the template. As these are the building blocks of your pages, it's worth
+looking at precisely what variables are available.
+
+The most important variable is called C<objects>, and is a list of all
+the objects that this page is going to deal with. For instance,
+in the template F</beer/view>, C<objects> will contain the C<BeerDB::Beer>
+object for the 23rd item in the database, while F</brewery/list> will
+fill C<objects> will all the breweries; or at least, all the breweries
+on the current page.
+
+This variable is so important that to help design templates with it,
+C<Maypole::View::TT> provides a helpful alias to it depending on
+context. For instance, if you're writing your own F</brewery/list>
+template, the data in C<objects> is also available in a template
+variable called C<breweries>. If you're working on F</brewery/view>,
+though, it's available in C<brewery>, since there's only one brewery to
+be displayed.
+
+Additionally, you can get the base URL for the application from the
+C<base> template variable; this allows you to construct links, as we
+saw earlier:
+
+ <A HREF="[% base %]/brewery/edit/[% brewery.id %]">Edit this brewery</A>
+
+You can also get at the rest of the configuration for the site with the
+C<config> variable as we saw above, and the entire request object in
+C<request>, should you really need to poke at it. (I've only found this
+useful when working with authentication modules which stash a current user
+object in C<request.user>.)
+
+To allow the construction of the "generic" templates which live in
+F<factory>, Maypole also passes in a hash called C<classmetadata>,
+which contains all sorts of useful information about the class under
+examination:
+
+=over 3
+
+=item C<table>
+
+This is the name of the table that is represented by the class.
+
+=item C<class>
+
+This is the Perl's idea of the class; you don't need this unless you're
+doing really tricky things.
+
+=item C<moniker>
+
+This is a more human-readable version of the table name, that can be
+used for display.
+
+=item C<plural>
+
+The same, but a correctly-formed plural. For instance, "breweries".
+
+=item C<columns>
+
+The list of columns for display; see the section "Customizing Generic
+CRUD Applications" in L<StandardTemplates.pod>.
+
+=item C<colnames>
+
+This is a hash mapping the database's name for a column to a more
+human-readable name. Again, see "Customizing Generic CRUD Applications>.
+
+=item C<cgi>
+
+This is a slightly trickier one. It is a hash mapping column names to
+a C<HTML::Element> suitable for entering data into a new instance of
+that class. That is, for the C<beer> table, C<classmetadata.cgi.style>
+should be a C<HTML::Element> object containing a drop-down list of
+beer styles. This is explained in L<StandardTemplates.pod>.
+
+=item C<description>
+
+This is the human-readable description provided by a class.
+
+=item C<related_accessors>
+
+This is a list of accessors which can be called on an object to get
+lists of other things that this object "has". For instance, on a
+brewery, it would return C<beers>, since calling C<brewery.beers> would
+give you a list of beers produced by the brewery. Note that this only
+caters for accessors defining one-to-many relationships, not the
+ordinary one-to-one relationships, such as C<style>.
+
+=back
+
+=head2 Other view classes
+
+Please note that these template variables, C<config>, C<classmetadata>,
+C<objects> and its user-friendly alias, as well as the rest of them are
+a function of one particular view class, the default
+C<Maypole::View::TT> class. Other view classes may need to present an
+entirely different set of template variables, since the default ones
+might not make sense. The templates may look wildly different in other
+view class implementations. But that's OK, because you couldn't
+necessarily use the same templates with a different templating system
+anyway.
+
+For instance, in really dumb templating languages which can't handle
+dereferencing hashes or arrays - no wait, that's most of them - passing
+in a hash reference like C<classmetadata> won't help you since you can't
+get at any of its elements. So you'll need to take a look at the
+documentation for the appropriate view class to see what template
+variables it provides.
+
+So if, for some perverse reason, the Template Toolkit just isn't good
+enough for you, then you can set your own view class while configuring
+your application:
package BeerDB;
use base 'Apache::MVC';
through CGI parameters and the like, so we have to fiddle a bit to get
these variables into our template.
-XXX
+
projects / maypole.git / commitdiff