Man pages sections > man3 > Config::Model::Backend::Yaml

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

Config::Model::Backend::Yaml(3pm) User Contributed Perl Documentation Config::Model::Backend::Yaml(3pm)

NAME

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

VERSION

version 2.113

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',
            },
        },
    ],
  rw_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 <https://github.com/ingydotnet/yaml-libyaml-pm/issues/45>. 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 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
2017-10-13 perl v5.26.0