NAME¶
SVN::Web::action - base class for SVN::Web::actions
DESCRIPTION¶
This is the base class for all SVN::Web actions. It provides a constructor and
some useful utility methods that actions may find useful. It also contains
documentation for anyone interested in writing new SVN::Web actions.
OVERVIEW¶
SVN::Web actions are Perl modules loaded by SVN::Web. They are expected to
retrieve some information from the Subversion repository, and return that
information ready for the user's browser, optionally via formatting by a
Template::Toolkit template.
Action names are listed in the SVN::Web configuration file,
config.yaml,
in the "actions:" clause. Each entry specifies the class that
implements the action, options that are set globally for that action, and
metadata that describes when and how the action should appear in the action
menu.
actions:
...
new_action:
class: Class::That::Implements::Action
action_menu: # Optional
show:
- file # Zero or more of this, ...
- directory # ... this ...
- revision # ... or this.
- global # Or possibly just this one
link_text: (text) # Mandatory
head_only: 1 # Optional
icon: /a/path # Optional
opts:
option1: value1
option2: value2
...
Each action is a class that must implement a "run()" method.
SUBCLASSING¶
Actions should derive from SVN::Web::action. This gives them a default
constructor that generates a hash based object.
use base 'SVN::Web::action';
METHODS¶
run()¶
The "run" method is where the action carries out its work.
Parameters
The method is passed a single parameter, the standard $self hash ref. This
contains numerous useful keys.
- $self->{opts}
- The options for this action from config.yaml. Using the example
from the OVERVIEW, this would lead to:
$self->{opts} = { 'option1' => 'value1',
'option2' => 'value2',
};
- $self->{cgi}
- An instance of a CGI compatible object corresponding to the current
request. This is normally an object from either the CGI or CGI::Fast
modules, although it is possible to specify another class with the
"cgi_class" directive in config.yaml. Since we now use
Plack, this is a Plack::Request object.
You can use this object to retrieve the values of any parameters passed to
your action.
For example, if your action takes a "rev" parameter, indicating
the repository revision to work on;
my $rev = $self->{cgi}->param('rev');
- $self->{path}
- The path in the repository that was passed to the action.
- $self->{navpaths}
- A reference to an array of path components, one for each directory (and
possible final file) in $self->{path}. Equivalent to
"[ split('/', $self->{path}) ]"
- $self->{config}
- The config hash, as read by YAML from config.yaml. Directives from
the config file are second level hash keys. For example, the
"actions" configuration directive contains a list of valid
actions.
my @valid_actions = @{ $self->{config}->{actions} };
- $self->{reposname}
- The symbolic name of the repository being accessed.
- $self->{repos}
- A instance of the SVN::Repos class, corresponding to the repository being
accessed. This repository has already been opened.
For example, to find the youngest (i.e., most recent) revision of the
repository;
my $yr = $self->{repos}->fs()->youngest_rev();
- $self->{action}
- The action that has been requested. It's possible for multiple action
names to be mapped to a single class in the config file, and this lets you
differentiate between them.
- $self->{script}
- The URL for the currently running script.
Return value
The return value from "run()" determines how the data from the action
is displayed.
Using a template
If "run()" wants a template to be displayed containing formatted data
from the method then the hash ref should contain two keys.
- template
- This is the name of the template to return. By convention the template and
the action share the same name.
- data
- This is a hash ref. The hash keys become variables of the same name in the
template.
The character set and MIME type can also be specified, in the
"charset" and "mimetype" keys. If these values are not
specified then they default to "UTF-8" and "text/html"
respectively.
E.g., for an action named "my_action", using a template called
"my_action" that looks like this:
<p>The youngest interesting revision of [% file %] is [% rev %].</p>
then this code would be appropriate.
# $rev and $file set earlier in the method
return { template => 'my_action',
data => { rev => $rev,
file => $file,
},
};
Returning data with optional charset and MIME type
If the action does not want to use a template and just wants to return data, but
retain control of the character set and MIME type, "run()" should
return a hash ref. This should contain a key called "body", the
value of which will be sent directly to the browser.
The character set and MIME type can also be specified, in the
"charset" and "mimetype" keys. If these values are not
specified then they default to "UTF-8" and "text/html"
respectively.
E.g., for an action that generates a PNG image from data in the repository
(perhaps using SVN::Churn);
# $png contains the PNG image, created earlier in the method
return { mimetype => 'image/png',
body => $png
};
Returning HTML with default charset and MIME type
If the action just wants to return HTML in UTF-8, it can return a single scalar
that contains the HTML to be sent to the browser.
return "<p>hello, world</p>";
UTILITY METHODS¶
The following methods are intended to share common code among actions.
recent_interesting_rev($path, $rev)¶
Given a repository path, and a revision number, returns the most recent
interesting revision for the path that is the same as, or older (i.e.,
smaller) than the revision number.
If called in an array context it returns all the arguments normally passed to a
log message receiver.
get_revs()¶
Returns a list of 4 items. In order, they are:
- Explicit rev
- The value of any CGI "rev" parameter passed to the action
($exp_rev).
- Youngest rev
- The repository's youngest revision ($yng_rev) for the current path. This
is not necessarily the same as the repositories youngest revision.
- Actual rev
- The actual revision ($act_rev) that will be acted on. This is the explicit
rev, if it's defined, otherwise it's the youngest rev.
- Head
- A boolean value indicating whether or not we can be considered to be at
the HEAD of the repository ($at_head).
Given a cstring that represents a Subversion time, format the time using
POSIX::strftime() and the current settings of the
"timedate_format" and "timezone" configuration directives.
CACHING¶
If the output from the action can usefully be cached then consider implementing
a "cache_key" method.
This method receives the same parameters as the "run()" method, and
must use those parameters to generate a unique key for the content generated
by the "run()" method.
For example, consider the standard "Revision" action. This action only
depends on a single parameter -- the repository revision number. So that makes
a good cache key.
sub cache_key {
my $self = shift;
return $self->{cgi}->param('rev');
}
Other actions may have more complicated keys.
ERRORS AND EXCEPTIONS¶
If your action needs to fail for some reason -- perhaps the parameters passed to
it are incorrect, or the user lacks the necessary permissions, then throw an
exception.
Exceptions, along with examples, are described in SVN::Web::X.
COPYRIGHT¶
Copyright 2005-2007 by Nik Clayton "<nik@FreeBSD.org>".
Copyright 2012 by Dean Hamstead "<dean@fragfest.com.au>".
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.
See <
http://www.perl.com/perl/misc/Artistic.html>