NAME¶

Config::Model::BackendMgr - Load configuration node on demand

VERSION¶

version 2.152

SYNOPSIS¶

 # Use BackendMgr to write data in Yaml file
 # This example requires Config::Model::Backend::Yaml which is now
 # shipped outside of Config::Model. Please get it on CPAN
 use Config::Model;
 # define configuration tree object
 my $model = Config::Model->new;
 $model->create_config_class(
    name    => "Foo",
    element => [
        [qw/foo bar/] => {
            type       => 'leaf',
            value_type => 'string'
        },
    ]
 );
 $model->create_config_class(
    name => "MyClass",
    # rw_config spec is used by Config::Model::BackendMgr
    rw_config => {
        backend     => 'yaml',
        config_dir  => '/tmp/',
        file        => 'my_class.yml',
        auto_create => 1,
    },
    element => [
        [qw/foo bar/] => {
            type       => 'leaf',
            value_type => 'string'
        },
        hash_of_nodes => {
            type       => 'hash',     # hash id
            index_type => 'string',
            cargo      => {
                type              => 'node',
                config_class_name => 'Foo'
            },
        },
    ],
 );
 my $inst = $model->instance( root_class_name => 'MyClass' );
 my $root = $inst->config_root;
 # put data
 my $steps = 'foo=FOO hash_of_nodes:fr foo=bonjour -
   hash_of_nodes:en foo=hello ';
 $root->load( steps => $steps );
 $inst->write_back;
 # now look at file /tmp/my_class.yml

DESCRIPTION¶

This class provides a way to specify how to load or store configuration data within the model.

With these specifications, all configuration information is read during creation of a node (which triggers the creation of a backend manager object) and written back when write_back method is called either on the instance.

This load/store can be done with different backends:

• Any of the "Config::Model::Backend::*" classes available on your system. For instance "Config::Model::Backend::Yaml".
• "cds_file": Config dump string (cds) in a file. I.e. a string that describes the content of a configuration tree is loaded from or saved in a text file. This format is defined by this project. See "load string syntax" in Config::Model::Loader.
• "perl_file": Perl data structure (perl) in a file. See Config::Model::DumpAsData for details on the data structure. Now handled by Config::Model::Backend::PerlFile

When needed, "write_back" method can be called on the instance (See Config::Model::Instance) to store back all configuration information.

Backend specification¶

The backend specification is provided as an attribute of a Config::Model::Node specification. These attributes are optional: A node without "rw_config" attribute must rely on another node to read or save its data.

When needed (usually for the root node), the configuration class is declared with a "rw_config" parameter which specifies the read/write backend configuration.

 rw_config => {
     backend     => 'yaml',
     config_dir  => '/tmp/',
     file        => 'my_class.yml',
 },

Test setup¶

By default, configurations files are read from the directory specified by "config_dir" parameter specified in the model. You may override the "root" directory for test.

Methods¶

AUTHOR¶

Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO¶

Config::Model, Config::Model::Instance, Config::Model::Node, Config::Model::Dumper

AUTHOR¶

Dominique Dumont

COPYRIGHT AND LICENSE¶

This software is Copyright (c) 2005-2022 by Dominique Dumont.

This is free software, licensed under:

  The GNU Lesser General Public License, Version 2.1, February 1999