---
name: "Config::Model::Backend::Json"
section: "3pm"
platform: "linux"
package: "libconfig-model-perl"
version: "2.155-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Config::Model::Backend::Json"
---

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

Read and write config as a JSON data structure

## NAME

Config::Model::Backend::Json - Read and write config as a JSON data structure

## VERSION

version 2.155

## 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 => 'Json' ,
    config_dir => '/tmp',
    file  => 'foo.json',
    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",
   "foo" : "yada",
   "baz" : {
      "hr" : "dobar dan",
      "en" : "hello",
      "fr" : "bonjour"
   }
 }
```

## DESCRIPTION

This module is used directly by Config::Model to read or write the content of a configuration tree written with Json syntax in `"Config::Model"` configuration tree.

Note that undefined values are skipped for list element. I.e. if a list element contains `"('a',undef,'b')"`, the data structure only contains `'a','b'`.

## CONSTRUCTOR

### new

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

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

### read

Of all parameters passed to this read call-back, only `"file_path"` is used. This parameter must be a Path::Tiny.

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

### write

Of all parameters passed to this write call-back, only `"file_path"` is used. This parameter must be Path::Tiny object.

`"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) 2005-2022 by Dominique Dumont.

This is free software, licensed under:

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