NAME CGI::Application::Plugin::Config::Context - Hierarchical, context-based configuration support for CGI::Application VERSION Version 0.16 SYNOPSIS Simple Access to Configuration In your CGI::Application-based module: use base 'CGI::Application'; use CGI::Application::Plugin::Config::Context; sub cgiapp_init { my $self = shift; # Set config file and other options $self->conf->init( file => 'app.conf', driver => 'ConfigGeneral', ); } sub my_run_mode { my $self = shift; # get entire configuration my %conf = $self->conf->context; # get entire configuration (as a reference) my $conf = $self->conf->context; # get single config parameter my $value = $self->conf->param('some_value'); # get raw configuraion (pre-context-matching) my $raw_config = $self->conf->raw; my %raw_config = $self->conf->raw; } Configuration Based on URL or Module You can match a configuration section to the request URL, or to the module name. For instance, given the following configuration file: admin_area = 0 admin_area = 1 title = Admin Area title = Feedback Form The configuration will depend on how the script is called: # URL: /cgi-bin/feedback.cgi?rm=add # Module: MyApp::Feedback print $self->conf->param('admin_area'); # 0 print $self->conf->param('title'); # 'Feedback Form' # URL: /cgi-bin/admin/users.cgi # Module: MyApp::Admin::Users print $self->conf->param('admin_area'); # 1 print $self->conf->param('title'); # 'Admin Area' Matching Configuration based on a Virtual Host This module can also pick a configuration section based on the current virtual-host: # httpd.conf SetEnv SITE_NAME REDSITE # in app.conf background = blue foreground = white background = red foreground = pink background = darkgreen foreground = lightgreen Multiple configuration formats Supports any configuration format supported by Config::Context. As of this writing, that includes the following formats: Apache-style syntax, via Config::General: admin_area = 1 title = Admin Area title = Feedback Form XML, via XML::Simple: 1 Admin Area Feedback Form Config::Scoped syntax: AppMatch '^MyApp::Admin' { admin_area = 1 title = Admin Area } Location '/cgi-bin/feedback.cgi' { title = Feedback Form } Most of the examples in this document are in Config::General syntax, but can be translated into the other formats fairly easily. For more information, see the Config::Context docs. DESCRIPTION This module allows you to easily access configuration data stored in any of the formats supported by Config::Context: Config::General (Apache style), XML::Simple and Config::Scoped. You can also automatically match configuration sections to the request URL, or to the module name. This is similar to how Apache dynamically selects a configuration by matching the request URL to (for instance) "" and "" sections. You can also select configuration sections based on Virtual Host or by an environment variable you set in an ".htaccess" file. This allows you to share a configuration file and an application between many virtual hosts, each with its own unique configuration. This could be useful, for instance, in providing multiple themes for a single application. Simple access to Configuration This module provides a "conf" method to your CGI::Application object. First, you initialize the configuration system (typically in your "cgiapp_init" method): $self->conf->init( file => 'app.conf', driver => 'ConfigGeneral', ); The configuration file is parsed at this point and the configuration is available from this moment on. Then, within your run-modes you can retrieve configuration data: # get entire configuration my %conf = $self->conf->context; my $value = $conf{'some_value'}; # get entire configuration (as a reference) my $conf = $self->conf->context; my $value = $conf->{'some_value'}; # get single config parameter my $value = $self->conf->param('some_value'); The "context" method provides the configuration based on the "context" of your application, i.e. after matching configuration sections based on runtime data such as the current URL or package name. But you can also access the raw configuration data from before the matching took place: # get raw configuration my %conf = $self->conf->raw; # get raw configuration (as a reference) my $conf = $self->conf->raw; Multiple named Configurations You can use more than one configuration by providing a name to the "conf" method: $self->conf('database')->init( file => 'app.conf', driver => 'ConfigGeneral', ); $self->conf('application')->init( file => 'app.conf', driver => 'ConfigScoped', ); ... my %db_config = $self->conf('database')->context; my %app_config = $self->conf('application')->context; Configuration based on URL or Module Within your configuration file, you can provide different configurations depending on the current URL, or on the package name of your application. Matches against the "SITE_NAME" environment variable, using an *exact* match. # httpd.conf SetEnv SITE_NAME REDSITE # in app.conf background = blue foreground = white background = red foreground = pink background = darkgreen foreground = lightgreen You can name your sections something other than "", and you can use a different environment variable than "SITE_NAME". See "Notes on Site Matching", below. Matches the Package name of your application module, for instance: ... The match is performed hierarchically, like a filesystem path, except using "::" as a delimiter, instead of "/". The match is tied to the beginning of the package name, just like absolute paths. For instance, given the section: ... the packages "Site::Admin" and "Site::Admin::Users" would match, but the packages "My::Site::Admin" and "Site::Administrative" would not. Matches the package name of your application module, using a regular expression. The expression is not tied to the start of the string. For instance, given the section: ... The following packages would all match: "Site::Admin", "Site::Admin::Users", "My::Site::Admin", "MySite::Admin", "Site::Administrative". Matches hierarchically against the request URI, including the path and the "PATH_INFO" components, but *excluding* the scheme, host, port and query string. So, for instance with the following URL: http://bookstore.example.com/cgi-bin/category.cgi/fiction/?rm=list The Location would be: /cgi-bin/category.cgi/fiction/ Internally, the location is obtained by calling the "url" method of the query object (which is usually either a CGI or CGI::Simple object): $path = $webapp->query->url('-absolute' => 1, '-path_info' => 1); Matches against the request URI, using a regular expression. Section Merge Order The sections are matched in the following order: Site: Package Name: and URL: and When there is more than one matching section at the same level of priority (e.g. two "" sections, or both an "" and an "" section), then the sections are merged in the order of shortest match first. Values in sections matched later override the values in sections matched earlier. The idea is that the longer matches are more specific and should have priority, and that URIs are more specific than Module names. Section Nesting The sections can be nested inside each other. For instance: admin_books = 1 admin_records = 1 By default, the sections can be nested up to two levels deep. This alows for "Location" sections within "Site" sections and *vice versa*. You can change this by setting the nesting_depth parameter to init. Note: there is limited support for this kind of nesting when using Config::Scoped format files. See the documentation in Config::Context::ConfigScoped for details. Merging Configuration Values into your Template You can easily pass values from your configuration files directly to your templates. This allows you to associate HTML titles with URLs, or keep text like copyright notices in your config file instead of your templates: copyright_notice = Copyright (C) 1492 Christopher Columbus title = "Manifest Destiny, Inc. - About Us" title = "Manifest Destiny, Inc. - Contact Us" If you use HTML::Template, you use the associate method when you load the template: $self->load_template( 'template.tmpl', 'associate' => $self->conf, ); If you use Template::Toolkit (via the CGI::Application::Plugin::TT module), you can accomplish the same thing by providing a custom tt_pre_process method: sub tt_pre_process { my $self = shift; my $template = shift; my $template_params = shift; my $config = $self->conf->context foreach (keys %$config) { unless (exists $template_params->{$_}) { $template_params->{$_} = $config->{$_}; } } } *NOTE: If you plan to merge data directly from your config files to your* *templates, you should consider keeping your database passwords and other* *sensitive data in a separate configuration file, in order to avoid* *accidentally leaking these data into your web pages.* METHODS init Initializes the plugin. The only required parameter is the source of the configuration, either "file", "string" or "hash". $self->conf->init( file => 'app.conf', ); The other paramters are described below: file The path to the configuration file to be parsed. string A string containing configuration data to be parsed. hash A Perl data structure containing containing the pre-parsed config data. driver Which Config::Context driver should parse the config. Currently supported drivers are: driver module name ------ ----------- ConfigGeneral Config::Context::ConfigGeneral ConfigScoped Config::Context::ConfigScoped XMLSimple Config::Context::XMLSimple The default driver is "ConfigGeneral". driver_options Options to pass directly on to the driver. This is a multi-level hash, where the top level keys are the driver names: my $conf = Config::Context->new( driver => 'ConfigScoped', driver_options => { ConfigGeneral => { -AutoLaunder => 1, }, ConfigScoped = > { warnings => { permissions => 'off', } }, }, ); In this example the options under "ConfigScoped" will be passed to the "ConfigScoped" driver. (The options under "ConfigGeneral" will be ignored because "driver" is not set to 'ConfigGeneral'.) cache_config_files Whether or not to cache configuration files. Enabled, by default. This option is useful in a persistent environment such as "mod_perl". See "Config File Caching" under "ADVANCED USAGE", below. stat_config If config file caching is enabled, this option controls how often the config files are checked to see if they have changed. The default is 60 seconds. This option is useful in a persistent environment such as "mod_perl". See "Config File Caching" under "ADVANCED USAGE", below. site_section_name Change the name of the "" section to something else. For instance, to use sections named "", use: site_section_name => 'VirtualHost' site_var Change the name of the "SITE_NAME" environment variable used to match against "" sections. For instance To change this name to "HTTP_HOST", use: site_var => 'HTTP_HOST', nesting_depth The number of levels deep that sections can be nested. The default is two levels deep. See "Section Nesting", above. You can initialize the plugin from within your instance CGI script: my $app = WebApp->new(); $app->conf->init(file => '../../config/app.conf'); $app->run(); Or you can do so from within your "cgiapp_init" method within the application: sub cgiapp_init { my $self = shift; $self->conf->init( file => "$ENV{DOCUMENT_ROOT}/../config/app.conf" ); } context Gets the entire configuration as a hash or hashref: my %config = $self->conf->context; # as hash my $config = $self->conf->context; # as hashref raw Gets the raw configuration as a hash or hashref: my %raw_config = $self->conf->raw; # as hash my $raw_config = $self->conf->raw; # as hashref The raw configuration is the configuration before matching has taken place. It includes all the raw config with all of the "", "", etc. sections intact. param Allows you to retrieve individual values from the configuration. It behvaves like the "param" method in other classes, such as CGI, CGI::Application and HTML::Template: $value = $self->conf->param('some_key'); @all_keys = $self->conf->param(); get_current_context ($name) This is a class method which returns the current configuration object. my $conf = CGI::Application::Plugin::Config::Context->get_current_context; print $conf->{'title'}; my %db_conf = CGI::Application::Plugin::Config::Context->get_current_context('db'); print $db_conf{'username'}; This method is most useful in situations where you don't have access to the CGI::Application object, such within a Class::DBI class. See "Access to Configuration information from another Class" for an example. get_current_raw_config ($name) Same as get_current_context, but returns the raw configuration. ADVANCED USAGE Usage in a Persistent Environment such as mod_perl The following sections describe some notes about running this module under mod_perl: Config File Caching Config::Context caches configuration files by default. Each config file is read only once when the conf object is first initialized. Thereafter, on each init, the cached config is used. This means that in a persistent environment like mod_perl, the config file is parsed on the first request, but not on subsequent requests. If enough time has passed (sixty seconds by default) the config file is checked to see if it has changed. If it has changed, then the file is reread. See the docs for Config::Context for details. Notes on Site Matching Renaming "" or "SITE_NAME" Normally, the environment variable "SITE_NAME" is matched to "" section. You can change these with the site_section_name and site_var parameters to init: $self->conf->init( file => 'app.conf', site_section_name => 'Host', site_var => 'MY_HOST', ); This will match the environment variable "MY_HOST" to the "" section. Setting "SITE_NAME" from an ".htaccess" file or the CGI script Since "SITE_NAME" is just an environment variable, you can set it anywhere you can set environment variables. For instance in an ".htaccess" file: # .htaccess SetEnv SITE_NAME bookshop Or even the calling CGI script: #!/usr/bin/perl use MySite::WebApp; $ENV{'SITE_NAME'} = 'recordshop'; my $app = MySite::WebApp->new(); $app->run(); Access to Configuration information from another Class You can also get at the current configuration settings from a completely unrelated Perl module. This can be useful for instance if you need to configure a set of Class::DBI classes, and you want them to be able to pick up their configuration on their own. For instance: # app.conf connect_string = dbi:Pg:dbname=example username = test password = test RaiseError = 1 AutoCommit = 1 # In your Class::DBI subclass package My::Class::DBI::Base; use base 'Class::DBI'; sub db_Main { my $conf = CGI::Application::Plugin::Config::Context->get_current_context; my $dsn = $conf->{'database'}{'connect_string'}; my $user = $conf->{'database'}{'username'}; my $pass = $conf->{'database'}{'password'}; my $opts = $conf->{'database'}{'options'}; return DBI->connect_cached($dsn, $user, $pass, $opts); } For this example to work, you need to make sure you call "$self->conf->init" before you access the database through any of your Class::DBI objects. You can also call get_current_raw_config to get access to the raw configuration. Changing Parsing Behaviour Using Custom match_sections Internally, this module uses Config::Context to parse its config files. If you want to change the parsing behaviour, you can pass your own match_sections list to init. For instance, if you want to allow only sections named "", with no nesting, and have these matched exactly to the complete request path, you could do the following: # app.conf admin_area = 0 user_area = 0 admin_area = 1 user_area = 1 # in your cgiapp_init: $self->conf->init( file => 'app.conf', nesting_depth => 1, match_sections => [ { name => 'URL', match_type => 'exact', merge_priority => 0, section_type => 'path', }, ] ); For reference, here is the default match_sections: [ { name => 'Site', # overridden by 'site_section_name' match_type => 'exact', merge_priority => 0, section_type => 'env', }, { name => 'AppMatch', match_type => 'regex', section_type => 'module', merge_priority => 1, }, { name => 'App', match_type => 'path', path_separator => '::', section_type => 'module', merge_priority => 1, }, { name => 'LocationMatch', match_type => 'regex', section_type => 'path', merge_priority => 3, }, { name => 'Location', match_type => 'path', section_type => 'path', merge_priority => 3, }, ], For each section, the section_type param indicates what runtime variable the section will be matched against. Here are the allowed values env: matched to the environment variable SITE_NAME (overridden by site_name_var) module: name of the Perl Module handling this request (e.g. MyApp::Users) path: path of the request, including path_info (e.g. /cgi-bin/myapp/users.cgi/some/path) You can use the above section_type values in your own custom match_sections. For more information on the syntax of match_sections, see the docs for Config::Context. Importing the 'conf' method, but using a different name. If you want to access the features of this module using a method other than "conf", you can do so via Anno Siegel's Exporter::Renaming module (available on CPAN). use Exporter::Renaming; use CGI::Application::Plugin::Config::Context Renaming => [ conf => custom_config_method]; sub cgiapp_init { my $self = shift; # Set config file and other options $self->custom_config_method->init( file => 'app.conf', driver => 'ConfigGeneral', ); my $config = $self->custom_config_method->context; # .... } AUTHOR Michael Graham, "" BUGS Please report any bugs or feature requests to "bug-cgi-application-plugin-config-general@rt.cpan.org", or through the web interface at . I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. ACKNOWLEDGEMENTS Thanks to the excellent examples provided by the other CGI::Application plugin authors: Mark Stosberg, Michael Peters, Cees Hek and others. SEE ALSO CGI::Application Config::Context Config::Context::ConfigGeneral Config::Context::ConfigScoped Config::Context::XMLSimple CGI::Application::Plugin::Config::Simple CGI::Application::Plugin::ConfigAuto Exporter::Renaming CGI::Application::Plugin::TT Template::Toolkit HTML::Template COPYRIGHT & LICENSE Copyright 2005 Michael Graham, All Rights Reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.