/ 
Config-Model-2.103
River stage two • 11 direct dependents • 11 total dependents
/ Config::Model::Backend::Yaml

NAME

Config::Model::Backend::Yaml - Read and write config as a YAML data structure

VERSION

version 2.103

SYNOPSIS

use Config::Model ;
use Data::Dumper ;

# define configuration tree object
my $model = Config::Model->new ;
$model ->create_config_class (
   name => "MyClass",
   element => [ 
       [qw/foo bar/] => { 
           type => 'leaf',
           value_type => 'string'
       },
       baz => { 
           type => 'hash',
           index_type => 'string' ,
           cargo => {
               type => 'leaf',
               value_type => 'string',
           },
       },
   ],
 read_config  => [
                   { backend => 'yaml' , 
                     config_dir => '/tmp',
                     file  => 'foo.yml',
                     auto_create => 1,
                   }
                 ],
) ;

my $inst = $model->instance(root_class_name => 'MyClass' );

my $root = $inst->config_root ;

my $steps = 'foo=yada bar="bla bla" baz:en=hello
            baz:fr=bonjour baz:hr="dobar dan"';
$root->load( steps => $steps ) ;
$inst->write_back ;

Now, /tmp/foo.yml contains:

---
bar: bla bla
baz:
  en: hello
  fr: bonjour
  hr: dobar dan
foo: yada

DESCRIPTION

This module is used directly by Config::Model to read or write the content of a configuration tree written with YAML syntax in Config::Model configuration tree.

Note:

  • Undefined values are skipped for list element. I.e. if a list element contains ('a',undef,'b'), the data structure contains 'a','b'.

  • YAML file is not created (and may be deleted) when no data is to be written.

Class with only one hash element

If the root node contains a single hash or list element, only the content of this hash is written in a YAML file.

For example, if a class contains:

element => [
  baz => {
      type => 'hash',
      index_type => 'string' ,
      cargo => {
          type => 'leaf',
          value_type => 'string',
      },
  },

If the configuration is loaded with:

$root->load("baz:one=un baz:two=deux")

Then the written YAML file does not show baz:

---
one: un
two: deux

Likewise, a YAML file for a class with a single list baz element would be written with:

---
- un
- deux

backend parameter

yaml_class

By default, this module uses YAML::Tiny. This module has the advantage of being light and secure. No Perl object can be created with YAML tags so YAML::Tiny can be used with YAML files coming from unutrusted sources.

On the other hand, YAML::Tiny does not support boolean values: it cannot write true and false as plain scalar. true and false are quoted and are not of type boolean from YAML point of view.

If this is a problem for your configuration files, you can use YAML module which writes true and false without quotes.

CONSTRUCTOR

new ( node => $node_obj, name => 'yaml' ) ;

Inherited from Config::Model::Backend::Any. The constructor is called by Config::Model::BackendMgr.

read ( io_handle => ... )

Of all parameters passed to this read call-back, only io_handle is used. This parameter must be IO::File object already opened for read.

It can also be undef. In which case read() returns 0.

When a file is read, read() returns 1.

write ( io_handle => ... )

Of all parameters passed to this write call-back, only io_handle is used. This parameter must be IO::File object already opened for write.

write() returns 1.

AUTHOR

Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO

Config::Model, Config::Model::BackendMgr, Config::Model::Backend::Any,

AUTHOR

Dominique Dumont

COPYRIGHT AND LICENSE

This software is Copyright (c) 2005-2017 by Dominique Dumont.

This is free software, licensed under:

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