---
name: "Config::Model::Backend::Yaml"
section: "3pm"
platform: "linux"
package: "libconfig-model-backend-yaml-perl"
version: "2.134-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Config::Model::Backend::Yaml"
---

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

Read and write config as a YAML data structure

## NAME

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

## VERSION

version 2.134

## 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
```

## 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

### yaml\_class

This parameter is ignored as of version 2.129.

## CONSTRUCTOR

### new

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

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

### read

Read YAML file and load into `$node_obj` tree.

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

### write

Write YAML File using `$node_obj` data.

`"write"` returns 1.

## AUTHOR

Dominique Dumont, (ddumont at cpan dot org)

## SEE ALSO

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

## AUTHOR

Dominique Dumont

## COPYRIGHT AND LICENSE

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
```

## SUPPORT

### Websites

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.

- •

  CPANTS

  The CPANTS is a website that analyzes the Kwalitee ( code metrics ) of a distribution.

  \<http://cpants.cpanauthors.org/dist/Config-Model-Backend-Yaml\>

- •

  CPAN Testers

  The CPAN Testers is a network of smoke testers who run automated tests on uploaded CPAN distributions.

  \<http://www.cpantesters.org/distro/C/Config-Model-Backend-Yaml\>

- •

  CPAN Testers Matrix

  The CPAN Testers Matrix is a website that provides a visual overview of the test results for a distribution on various Perls/platforms.

  \<http://matrix.cpantesters.org/?dist=Config-Model-Backend-Yaml\>

- •

  CPAN Testers Dependencies

  The CPAN Testers Dependencies is a website that shows a chart of the test results of all dependencies for a distribution.

  \<http://deps.cpantesters.org/?module=Config::Model::Backend::Yaml\>

### Bugs / Feature Requests

Please report any bugs or feature requests by email to `"ddumont at cpan.org"`, or through the web interface at \<https://github.com/dod38fr/config-model-backend-yaml/issues\>. 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 :)

\<http://github.com/dod38fr/config-model-backend-yaml\>

```
  git clone git://github.com/dod38fr/config-model-backend-yaml.git
```