Provided by: libconfig-model-backend-yaml-perl_2.133-2_all bug


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


       version 2.133


        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
          en: hello
          fr: bonjour
          hr: dobar dan
        foo: yada


       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.


       ·   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

YAML class

       As of v2.129, this backend uses YAML::XS 0.69 or later.

       For security reason, loading a Perl blessed object is disabled.

       Value of type boolean are written as boolean values in YAML files.

backend parameter

       This parameter is ignored as of version 2.129.


       Parameters: "( node => $node_obj, name => 'yaml' )"

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

       Read YAML file and load into $node_obj tree.

       When a file is read, "read" returns 1.

       Write YAML File using $node_obj data.

       "write" returns 1.


       Dominique Dumont, (ddumont at cpan dot org)


       Config::Model, Config::Model::BackendMgr, Config::Model::Backend::Any, YAML::XS


       Dominique Dumont


       This software is Copyright (c) 2018 by Dominique Dumont.

       This is free software, licensed under:

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


       The following websites have more information about this module, and may be of help to you.
       As always, in addition to those websites please use your favorite search engine to
       discover more resources.

       ·   Search CPAN

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   Bugs / Feature Requests
       Please report any bugs or feature requests by email to "ddumont at", or through
       the web interface at <>. You
       will be automatically notified of any progress on the request by the system.

   Source Code
       The code is open to the world, and available for you to hack on. Please feel free to
       browse it and play with it, or whatever. If you want to contribute patches, please send me
       a diff or prod me to pull from your repository :)


         git clone git://