Config::Model::Backend::Yaml (3)

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NAME

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

VERSION

version 2.106

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 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 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

file does not show "baz":

 ---
 one: un
 two: deux

Likewise, a

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 <github.com/ingydotnet/yaml-libyaml-pm/issues/45>. No Perl object can be created with tags so YAML::Tiny can be used with 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

point of view.

If this is a problem for your configuration files, you can use

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