NAME
    CGI::Application::Plugin::Config::Context - Hierarchical, context-based
    configuration support for CGI::Application

VERSION
    Version 0.13

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

        <AppMatch ^MyApp::Admin>
            admin_area = 1
            title      = Admin Area
        </AppMatch>

        <Location /cgi-bin/feedback.cgi>
            title      = Feedback Form
        </Location>

    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
        <VirtualHost _default_:8080>
            SetEnv SITE_NAME REDSITE
        </VirtualHost>

        # in app.conf
        <Site BLUESITE>
            background = blue
            foreground = white
        </Site>

        <Site REDSITE>
            background = red
            foreground = pink
        </Site>

        <Site GREENSITE>
            background = darkgreen
            foreground = lightgreen
        </Site>

  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:

        <AppMatch ^MyApp::Admin>
            admin_area = 1
            title      = Admin Area
        </AppMatch>

        <Location /cgi-bin/feedback.cgi>
            title      = Feedback Form
        </Location>

    XML, via XML::Simple:

        <AppMatch name="^MyApp::Admin">
            <admin_area>1</admin_area>
            <title>Admin Area</title>
        </AppMatch>

        <Location name="/cgi-bin/feedback.cgi">
            <title>Feedback Form</title>
        </Location>

    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)
    "<Location>" and "<LocationMatch>" 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.

    <Site>
        Matches against the "SITE_NAME" environment variable, using an
        *exact* match.

            # httpd.conf
            <VirtualHost _default_:8080>
                SetEnv SITE_NAME REDSITE
            </VirtualHost>

            # in app.conf
            <Site BLUESITE>
                background = blue
                foreground = white
            </Site>

            <Site REDSITE>
                background = red
                foreground = pink
            </Site>

            <Site GREENSITE>
                background = darkgreen
                foreground = lightgreen
            </Site>

        You can name your sections something other than "<Site>", and you
        can use a different environment variable than "SITE_NAME". See
        "Notes on Site Matching", below.

    <App>
        Matches the Package name of your application module, for instance:

            <App ABC_Books::Admin>
                ...
            </App>

        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:

            <App Site::Admin>
                ...
            </App>

        the packages "Site::Admin" and "Site::Admin::Users" would match, but
        the packages "My::Site::Admin" and "Site::Administrative" would not.

    <AppMatch>
        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:

            <AppMatch Site::Admin>
                ...
            </AppMatch>

        The following packages would all match: "Site::Admin",
        "Site::Admin::Users", "My::Site::Admin", "MySite::Admin",
        "Site::Administrative".

    <Location>
        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);

    <LocationMatch>
        Matches against the request URI, using a regular expression.

  Section Merge Order
    The sections are matched in the following order:

        Site:         <Site>
        Package Name: <App>      and <AppMatch>
        URL:          <Location> and <LocationMatch>

    When there is more than one matching section at the same level of
    priority (e.g. two "<Location>" sections, or both an "<App>" and an
    "<AppMatch>" 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:

        <Site BOOKSHOP>
            <Location /admin>
                admin_books = 1
            </Location>
        </Site>

        <Location /admin>
            <Site RECORDSHOP>
                admin_records = 1
            </Site>
        </Location>

        <App Bookshop::>
            <App Admin::>
            </App>
        </App>

    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

        <Location /about>
            title = "Manifest Destiny, Inc. -  About Us"
        </Location>

        <Location /contact>
            title = "Manifest Destiny, Inc. - Contact Us"
        </Location>

    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 "<Site>" section to something else. For
        instance, to use sections named "<VirtualHost>", use:

            site_section_name => 'VirtualHost'

    site_var
        Change the name of the "SITE_NAME" environment variable used to
        match against "<Site>" 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 "<Location>",
    "<App>", 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 "<Site>" or "SITE_NAME"
    Normally, the environment variable "SITE_NAME" is matched to "<Site>"
    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 "<Host>"
    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

        <database>
            connect_string = dbi:Pg:dbname=example
            username       = test
            password       = test

            <options>
                RaiseError = 1
                AutoCommit = 1
            </options>
        </database>

        # 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 "<URL>", 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

        <URL /cgi-bin/admin.cgi>
            admin_area = 1
        </URL>

        <URL /cgi-bin/user.cgi>
            user_area = 1
        </URL>

        # 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, "<mag-perl@occamstoothbrush.com>"

BUGS
    Please report any bugs or feature requests to
    "bug-cgi-application-plugin-config-general@rt.cpan.org", or through the
    web interface at <http://rt.cpan.org>. 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.