of this is that it can get into hash references and objects, and so
providing C<classmetadata>, C<config> and the Maypole request object
will work out just fine. The down side is that C<HTML::Mason> is used to
-having all the template variables it wants already at its disposal
-through CGI parameters and the like, so we have to fiddle a bit to get
-these variables into our template.
-
-
+running more or less standalone, and having all the template variables
+it wants already at its disposal through CGI parameters and the like, so
+we have to fiddle a bit to get these variables into our template.
+
+The key to building view classes is C<Maypole::View::Base>. This is the
+base class that you're going to inherit from and, to be honest, it does
+pretty much everything you need. It provides a method called C<vars>
+which returns a hash of all the template variables described above, so
+it would be good to feed those into C<HTML::Mason>. It also provides a
+C<paths> method which turns returns the full filesystem path of the
+three possible template paths as shown above. Again, it would be good to
+use this as our component paths if we can. It also has some methods we
+can override if we want to, but they're not massively important, so you
+can see L<Maypole::View::Base> for more about them.
+
+The module will do the right thing for us if we agree to provide a
+method called C<template>. This is responsible for taking the Maypole
+request object (of which more later) and putting the appropriate output
+either into C<$r-E<gt>{output}> or C<$r-E<gt>{error}>, depending, of
+course, whether things are OK or whether we got an error.
+
+Thankfully, C<HTML::Mason> makes things really easy for us. We B<can>
+use multiple template roots, so we can use the C<paths> method; we
+B<can> pass in a hash full of interesting data structures, so we can use
+the C<vars> method too. In fact, we have to do very little to make
+C<Maypole::View::Mason> work. Which is somewhat annoying, because it
+makes a boring example. But it means I can leave the fun ones to you!
+
+The doing-the-templating, in Mason and in any templating system, depends on
+three things: the paths that we're going to use to find our templates, the
+template name that we've been asked to fill out, and the set of variables that
+are going to be fed to the template. We'll assemble these for reference:
+
+ sub template {
+ my ($self, $r) = @_;
+ my @paths = $self->paths($r);
+ my $template = $r->template;
+ my %vars = $self->args($r);
+
+We'll also declare somewhere to temporarily store the output:
+
+ my $output;
+
+Now comes the part where we have to actually do something
+templating-language specific, so we open up our copy of "Embedding Perl
+in HTML with Mason" and find the bit where it talks about running Mason
+standalone. We find that the first thing we need to do is create a
+C<HTML::Mason::Interp> object which knows about the component roots.
+There's a slight subtlety in that the component roots have to be
+specified as an array of arrays, with each array being a two-element
+list of label and path, like so:
+
+ comproot => [
+ [ class => "/var/www/beerdb/templates/brewery" ],
+ [ custom => "/var/www/beerdb/templates/custom" ],
+ [ factory => "/var/www/beerdb/templates/factory" ],
+ ]
+
+We also find that we can set the output method here to capture Mason's
+output into a scalar, and also that we can tell Mason to generate
+sensible error messages itself, which saves us from having to worry
+about catching errors. At the end of all this, we come up with a
+constructor for our C<HTML::Mason::Interp> object which looks like this:
+
+ my $label = "path0";
+ my $mason = HTML::Mason::Interp->new(
+ comproot => [ map { [ $label++ => $_ ] } @paths ],
+ output_method => \$output,
+ error_mode => "output"
+ );
+
+The next thing we need to do is run the template with the appropriate
+template variables. This turns out to be really easy:
+
+ $mason->exec($template, %vars);
+
+Now we've got the data in C<$output>, we can put it into the request object,
+and return a true value to indicate that we processed everything OK. (If there
+was an error, then Mason will have produced some suitable output, so we can
+pretend that everything's OK anyway.)
+
+ $r->{output} = $output;
+ return 1;
+
+And that's all we need to do. Barely twenty lines of code for the finished
+product. Wasn't that easy? Don't you feel inspired to write Maypole view
+classes for your favourite templating language? Well, don't let me stop you!
+Patches are always welcome!
--- /dev/null
+package Maypole::View::Base;
+use File::Spec;
+use UNIVERSAL::moniker;
+use strict;
+
+sub new { bless {}, shift } # By default, do nothing.
+
+sub paths {
+ my ($self, $r) = @_;
+ my $root = $r->{config}{template_root} || $r->get_template_root;
+ return (
+ $root,
+ ($r->model_class &&
+ File::Spec->catdir($root, $r->model_class->moniker)),
+ File::Spec->catdir($root, "custom"),
+ File::Spec->catdir($root, "factory")
+ );
+}
+
+sub vars {
+ my ($self, $r) = @_;
+ my $class = $r->model_class;
+ my %args = (
+ request => $r,
+ objects => $r->objects,
+ base => $r->config->{uri_base},
+ config => $r->config
+ # ...
+ ) ;
+ if ($class) {
+ $args{classmetadata} = {
+ name => $class,
+ table => $class->table,
+ columns => [ $class->display_columns ],
+ colnames => { $class->column_names },
+ related_accessors => [ $class->related($r) ],
+ moniker => $class->moniker,
+ plural => $class->plural_moniker,
+ cgi => { $class->to_cgi },
+ description => $class->description
+ };
+
+ # User-friendliness facility for custom template writers.
+ if (@{$r->objects || []} > 1) {
+ $args{$r->model_class->plural_moniker} = $r->objects;
+ } else {
+ ($args{$r->model_class->moniker}) = @{$r->objects ||[]};
+ }
+ }
+
+ # Overrides
+ %args = (%args, %{$r->{template_args}||{}});
+ %args;
+}
+
+sub do_it {
+ my ($self, $r) = @_;
+ my $template = Template->new({ INCLUDE_PATH => [ $self->paths($r) ]});
+ my $output;
+ if ($template->process($r->template, { $self->args($r) }, \$output)) {
+ $r->{output} = $output;
+ return 1;
+ } else {
+ $r->{error} = $template->error;
+ }
+
+}
+
+sub process {
+ my ($self, $r) = @_;
+ $self->template($r) || return $self->error($r);
+ $r->{content_type} ||= "text/html";
+ return 200;
+}
+
+sub error {
+ my ($self, $r) = @_;
+ warn $r->{error};
+ if ($r->{error} =~ /not found$/) { return -1 }
+ $r->{content_type} = "text/plain";
+ $r->{output} = $r->{error};
+ $r->send_output;
+}
+
+sub template { die shift()." didn't define a decent template method!" }
+
+1;
--- /dev/null
+package Maypole::View::Mason;
+use base 'Maypole::View::Base';
+use HTML::Mason;
+
+sub template {
+ my ($self, $r) = @_;
+ my $label = "path0";
+ my $output;
+ my $mason = HTML::Mason::Interp->new(
+ comproot => [ map { [ $label++ => $_ ] } $self->paths($t) ],
+ output_method => \$output,
+ error_mode => "output" # Saves us having to handle them...
+ );
+ $mason->exec($r->template, $self->vars($r))
+ $r->{output} = $output;
+ return 1;
+}
+
+1;
+
+=head1 NAME
+
+Maypole::View::Mason - A HTML::Mason view class for Maypole
+
+=head1 SYNOPSIS
+
+ BeerDB->config->{view} = "Maypole::View::Mason";
+
+And then:
+
+ <%args>
+ @breweries
+ </%args>
+
+ % for my $brewery (@breweries) {
+ ...
+ <TD><% $brewery->name %></TD>
+ % }
+ ...
+
+=head1 DESCRIPTION
+
+This class allows you to use C<HTML::Mason> components for your Maypole
+templates. It provides precisely the same path searching and template
+variables as the Template Toolkit view class, although you will need
+to produce your own set of templates as the factory-supplied templates
+are, of course, Template Toolkit ones.
+
+Please see the Maypole manual, and in particular, the C<View> chapter,
+for the template variables available and for a refresher on how template
+components are resolved.
+
+=head1 AUTHOR
+
+Simon Cozens
+
+=head1 THANKS
+
+This module was made possible thanks to a Perl Foundation grant.
+
+=cut
package Maypole::View::TT;
-use Lingua::EN::Inflect;
+use base 'Maypole::View::Base';
use Template;
-use File::Spec;
-use UNIVERSAL::moniker;
-use strict;
-
-sub new { bless {}, shift } # Not worth having
-
-sub _tt {
+sub template {
my ($self, $r) = @_;
- # This bit sucks.
- my $root = $r->{config}{template_root} || $r->get_template_root;
- Template->new({ INCLUDE_PATH => [
- $root,
- ($r->model_class && File::Spec->catdir($root, $r->model_class->moniker)),
- File::Spec->catdir($root, "custom"),
- File::Spec->catdir($root, "factory")
- ]});
+ my $template = Template->new({ INCLUDE_PATH => [ $self->paths($r) ]});
+ my $output;
+ if ($template->process($r->template, { $self->vars($r) }, \$output)) {
+ $r->{output} = $output;
+ return 1;
+ } else {
+ $r->{error} = $template->error;
+ return 0;
+ }
}
-sub _args {
- my ($self, $r) = @_;
- my $class = $r->model_class;
- my %args = (
- request => $r,
- objects => $r->objects,
- base => $r->config->{uri_base},
- config => $r->config
- # ...
- ) ;
- if ($class) {
- $args{classmetadata} = {
- name => $class,
- table => $class->table,
- columns => [ $class->display_columns ],
- colnames => { $class->column_names },
- related_accessors => [ $class->related($r) ],
- moniker => $class->moniker,
- plural => $class->plural_moniker,
- cgi => { $class->to_cgi },
- description => $class->description
- };
+1;
- # User-friendliness facility for custom template writers.
- if (@{$r->objects || []} > 1) {
- $args{$r->model_class->plural_moniker} = $r->objects;
- } else {
- ($args{$r->model_class->moniker}) = @{$r->objects ||[]};
- }
- }
+=head1 NAME
- # Overrides
- %args = (%args, %{$r->{template_args}||{}});
- %args;
-}
+Maypole::View::TT - A Template Toolkit view class for Maypole
-sub process {
- my ($self, $r) = @_;
- my $template = $self->_tt($r);
- my $output;
- $template->process($r->template, { $self->_args($r) }, \$output)
- || return $self->error($r, $template->error);
+=head1 SYNOPSIS
- $r->{content_type} ||= "text/html";
- $r->{output} = $output;
- return 200;
-}
+ BeerDB->config->{view} = "Maypole::View::TT"; # The default anyway
-sub error {
- my ($self, $r, $error) = @_;
- warn $error;
- if ($error =~ /not found$/) { return -1 }
- $r->{content_type} = "text/plain";
- $r->{output} = $error;
- $r->send_output;
- exit;
-}
+=head1 DESCRIPTION
-1;
+This is the default view class for Maypole; it uses the Template Toolkit
+to fill in templates with the objects produced by Maypole's model classes.
+Please see the Maypole manual, and in particular, the C<View> chapter,
+for the template variables available and for a refresher on how template
+components are resolved.
+
+=head1 AUTHOR
+
+Simon Cozens
+
+=cut
projects / maypole.git / commitdiff