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.\" ========================================================================
.\"
.IX Title "Config::Model::Backend::Yaml 3pm"
.TH Config::Model::Backend::Yaml 3pm "2018-12-15" "perl v5.28.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Config::Model::Backend::Yaml \- Read and write config as a YAML data structure
.SH "VERSION"
.IX Header "VERSION"
version 2.130
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& 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 => \*(Aqleaf\*(Aq,
\&            value_type => \*(Aqstring\*(Aq
\&        },
\&        baz => { 
\&            type => \*(Aqhash\*(Aq,
\&            index_type => \*(Aqstring\*(Aq ,
\&            cargo => {
\&                type => \*(Aqleaf\*(Aq,
\&                value_type => \*(Aqstring\*(Aq,
\&            },
\&        },
\&    ],
\&  rw_config  => {
\&    backend => \*(Aqyaml\*(Aq,
\&    config_dir => \*(Aq/tmp\*(Aq,
\&    file  => \*(Aqfoo.yml\*(Aq,
\&    auto_create => 1,
\&  }
\& ) ;
\&
\& my $inst = $model\->instance(root_class_name => \*(AqMyClass\*(Aq );
\&
\& my $root = $inst\->config_root ;
\&
\& my $steps = \*(Aqfoo=yada bar="bla bla" baz:en=hello
\&             baz:fr=bonjour baz:hr="dobar dan"\*(Aq;
\& $root\->load( steps => $steps ) ;
\& $inst\->write_back ;
.Ve
.PP
Now, \f(CW\*(C`/tmp/foo.yml\*(C'\fR contains:
.PP
.Vb 7
\& \-\-\-
\& bar: bla bla
\& baz:
\&   en: hello
\&   fr: bonjour
\&   hr: dobar dan
\& foo: yada
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module is used directly by Config::Model to read or write the
content of a configuration tree written with \s-1YAML\s0 syntax in
\&\f(CW\*(C`Config::Model\*(C'\fR configuration tree.
.PP
Note:
.IP "\(bu" 4
Undefined values are skipped for list element. I.e. if a
list element contains \f(CW\*(C`(\*(Aqa\*(Aq,undef,\*(Aqb\*(Aq)\*(C'\fR, the data structure
contains \f(CW\*(Aqa\*(Aq,\*(Aqb\*(Aq\fR.
.IP "\(bu" 4
\&\s-1YAML\s0 file is not created (and may be deleted) when no data is to be
written.
.SS "Class with only one hash element"
.IX Subsection "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 \s-1YAML\s0 file.
.PP
For example, if a class contains:
.PP
.Vb 9
\&      element => [
\&        baz => {
\&            type => \*(Aqhash\*(Aq,
\&            index_type => \*(Aqstring\*(Aq ,
\&            cargo => {
\&                type => \*(Aqleaf\*(Aq,
\&                value_type => \*(Aqstring\*(Aq,
\&            },
\&        },
.Ve
.PP
If the configuration is loaded with:
.PP
.Vb 1
\& $root\->load("baz:one=un baz:two=deux")
.Ve
.PP
Then the written \s-1YAML\s0 file does \fBnot\fR show \f(CW\*(C`baz\*(C'\fR:
.PP
.Vb 3
\& \-\-\-
\& one: un
\& two: deux
.Ve
.PP
Likewise, a \s-1YAML\s0 file for a class with a single list \f(CW\*(C`baz\*(C'\fR element
would be written with:
.PP
.Vb 3
\& \-\-\-
\& \- un
\& \- deux
.Ve
.SH "backend parameter"
.IX Header "backend parameter"
.SS "yaml_class"
.IX Subsection "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 \s-1YAML\s0 tags so YAML::Tiny can be
used with \s-1YAML\s0 files coming from unutrusted sources.
.PP
On the other hand, YAML::Tiny does not support boolean values: it
cannot write \f(CW\*(C`true\*(C'\fR and \f(CW\*(C`false\*(C'\fR as plain scalar. \f(CW\*(C`true\*(C'\fR and
\&\f(CW\*(C`false\*(C'\fR are quoted and are not of type boolean from \s-1YAML\s0 point of view.
.PP
If this is a problem for your configuration files, you can use \s-1YAML\s0
module which writes \f(CW\*(C`true\*(C'\fR and \f(CW\*(C`false\*(C'\fR without quotes.
.SH "CONSTRUCTOR"
.IX Header "CONSTRUCTOR"
.SS "new"
.IX Subsection "new"
Parameters: \f(CW\*(C`( node => $node_obj, name => \*(Aqyaml\*(Aq )\*(C'\fR
.PP
Inherited from Config::Model::Backend::Any. The constructor is
called by Config::Model::BackendMgr.
.SS "read"
.IX Subsection "read"
Read \s-1YAML\s0 file and load into \f(CW$node_obj\fR tree.
.PP
When a file is read, \f(CW\*(C`read\*(C'\fR returns 1.
.SS "write"
.IX Subsection "write"
Write \s-1YAML\s0 File using \f(CW$node_obj\fR data.
.PP
\&\f(CW\*(C`write\*(C'\fR returns 1.
.SH "AUTHOR"
.IX Header "AUTHOR"
Dominique Dumont, (ddumont at cpan dot org)
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Config::Model, 
Config::Model::BackendMgr, 
Config::Model::Backend::Any,
.SH "AUTHOR"
.IX Header "AUTHOR"
Dominique Dumont
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is Copyright (c) 2005\-2018 by Dominique Dumont.
.PP
This is free software, licensed under:
.PP
.Vb 1
\&  The GNU Lesser General Public License, Version 2.1, February 1999
.Ve