Config::Model::Loader - Load serialized data into config tree


version 2.153


 use Config::Model;

 # define configuration tree object
 my $model = Config::Model->new;
    name    => "Foo",
    element => [
        [qw/foo bar/] => {
            type       => 'leaf',
            value_type => 'string'

 $model ->create_config_class (
    name => "MyClass",

    element => [

        [qw/foo bar/] => {
            type       => 'leaf',
            value_type => 'string'
        hash_of_nodes => {
            type       => 'hash',     # hash id
            index_type => 'string',
            cargo      => {
                type              => 'node',
                config_class_name => 'Foo'
        [qw/lista listb/] => {
                              type => 'list',
                              cargo =>  {type => 'leaf',
                                         value_type => 'string'
 ) ;

 my $inst = $model->instance(root_class_name => 'MyClass' );

 my $root = $inst->config_root ;

 # put data
 my $steps = 'foo=FOO hash_of_nodes:fr foo=bonjour -
   hash_of_nodes:en foo=hello
   ! lista=foo,bar lista:2=baz
     listb:0=foo listb:1=baz';
 $root->load( steps => $steps );

 my $s = $root->fetch_element_value('foo');      # => is 'FOO'
 $s = $root->grab_value('hash_of_nodes:en foo'); # => is 'hello'
 $s = $root->grab_value('lista:1');              # => is 'bar'
 $s = $root->grab_value('lista:2');              # => is 'baz'

 # delete some data
 $root->load( steps => 'lista~2' );

 $s = $root->grab_value('lista:2');              # => is undef

 # append some data
 $root->load( steps => q!hash_of_nodes:en foo.=" world"! );

 $s = $root->grab_value('hash_of_nodes:en foo'); # => is 'hello world'


This module is used directly by Config::Model::Node to load serialized configuration data into the configuration tree.

Serialized data can be written by the user or produced by Config::Model::Dumper while dumping data from a configuration tree.



The constructor should be used only by Config::Model::Node.



node ref of the root of the tree (of sub-root) to start the load from. Stored as a weak reference.

load string syntax

The string is made of the following items (also called actions) separated by spaces. These actions can be divided in 4 groups:

  • navigation: moving up and down the configuration tree.

  • list and hash operation: select, add or delete hash or list item (also known as id items)

  • leaf operation: select, modify or delecte leaf value

  • annotation: modify or delete configuration annotation (aka comment)


Go up one node


Go to the root node of the configuration tree.


Go down using xxx element. (For node type element)


Go up until the element xxx is found. This search can be combined with one of the command specified below, e.g /a_string="foo bar"

list and hash operation


Go down using xxx element and id yy (For hash or list element with node cargo_type). Literal \n are replaced by real \n (LF in Unix).

xxx:.foreach_match(yy) or xxx:~yy

Go down using xxx element and loop over the ids that match the regex specified by yy. (For hash).

For instance, with OpenSsh model, you could do

 Host:~"/.*" user='foo-guest'

to set "foo-user" users for all your debian accounts.

The leading and trailing '/' may be omitted. Be sure to surround the regexp with double quote if space are embedded in the regex.

Note that the loop ends when the load command goes above the element where the loop is executed. For instance, the instruction below tries to execute DX=BV and int_v=9 for all elements of std_id hash:

 std_id:~/^\w+$/ DX=Bv int_v=9

In the examples below only DX=BV is executed by the loop:

 std_id:~/^\w+$/ DX=Bv - int_v=9
 std_id:~/^\w+$/ DX=Bv ! int_v=9

The loop is done on all elements of the hash when no value is passed after ":~" (mnemonic: an empty regexp matches any value).

xxx:.rm(yy) or xxx:-yy

Delete item referenced by xxx element and id yy. For a list, this is equivalent to splice xxx,yy,1. This command does not go down in the tree (since it has just deleted the element). I.e. a '-' is generally not needed afterwards.

xxx:.rm_value(yy) or xxx:-=yy

Remove the element whose value is yy. For list or hash of leaves. Does not not complain if the value to delete is not found.

xxx:..rm_match(yy) or xxx:-~/yy/

Remove the element whose value matches yy. For list or hash of leaves. Does not not complain if no value were deleted.

xxx:.substitute(/yy/zz/) or xxx:=~s/yy/zz/

Substitute a value with another. Perl switches can be used(e.g. xxx:=~s/yy/zz/gi)

xxx:<yy or xxx:.push(yy)

Push yy value on xxx list

xxx:>yy or xxx:.unshift(yy)

Unshift yy value on xxx list

xxx:@ or xxx:.sort

Sort the list


Insert zz value on xxx list before index yy.


Insert zz value on xxx list before value yy.


Insert zz value on xxx list before value matching yy.


Insert zz value on xxx list so that existing alphanumeric order is preserved.


For hash element containing nodes: creates a new hash element with zz key on xxx hash so that existing alphanumeric order of keys is preserved. Note that all keys are sorted once this instruction is called. Following instructions are applied on the created element. I.e. putting key order aside, xxx:.insort(zz) has the same effect as xxx:zz instruction.


For hash element containing leaves: creates a new hash element with zz key and assing value vv so that existing alphanumeric order of keys is preserved. Note that all keys are sorted once this instruction is called. Putting key order aside, xxx:.insort(zz,vv) has the same effect as xxx:zz=vv instruction.


Ensure that list xxx contains value zz. If value zz is already stored in xxx list, this function does nothing. In the other case, value zz is inserted in alphabetical order.


Set list element xxx to list z1,z2,z3. Use ,, for undef values, and "" for empty values.

I.e, for a list ('a',undef,'','c'), use a,,"",c.


For hash element containing leaf cargo_type. Set the leaf identified by key yy to value zz.

Using xxx:~/yy/=zz is also possible.


copy item yy in zz (hash or list).


Store bar content in array or hash. This should be used to store hash or list of values.

You may store deep data structure. In this case, make sure that the structure of the loaded data matches the structure of the model. This won't happen by chance.


Clear the hash or list.

leaf operation


Set element xxx to value yy. load also accepts to set elements with a quoted string. (For leaf element) Literal \n are replaced by real \n (LF in Unix). Literal \\ are replaced by \.

For instance foo="a quoted string" or foo="\"bar\" and \"baz\"".


Apply the substitution to the value of xxx. s/foo/bar/ is the standard Perl s substitution pattern.

Patterns with white spaces must be surrounded by quotes:

  xxx=~"s/foo bar/bar baz/"

Perl pattern modifiers are accepted


Undef element xxx


Appends zzz value to current value (valid for leaf elements).


Store the content of file yyy in element xxx.

Store STDIn in value xxx when yyy is '-'.


Open file data.json and store value from JSON data extracted with foo/bar subpath.

For instance, if data.json contains:

    "foo": {
       "bar": 42

The instruction baz=.json(data.json/foo/bar) stores 42 in baz element.


Open file data.yaml and store value from YAML data extracted with 0/foo/bar subpath.

Since a YAML file can contain several documents (separated by --- lines, the subpath must begin with a number to select the document containing the required value.

For instance, if data.yaml contains:

    bar: 42

The instruction baz=.yaml(data.yaml/0/foo/bar) stores 42 in baz element.


Store the content of environment variable yyy in element xxx.


xxx#zzz or xxx:yyy#zzz

Element annotation. Can be quoted or not quoted. Note that annotations are always placed at the end of an action item.

I.e. foo#comment, foo:bar#comment or foo:bar=baz#comment are valid. foo#comment:bar is not valid.


You can surround indexes and values with single or double quotes. E.g.:

  a_string='"foo" and "bar"'

Single quotes were added in version 2.153.


You can use cme to modify configuration with cme modify command.

For instance, if Config::Model::Ssh is installed, you can run:

 cme modify ssh 'ControlMaster=auto ControlPath="~/.ssh/master-%r@%n:%p"'

To delete Host * entry:

 cme modify ssh 'Host:-"*"'

To specify 2 Host with a single command:

 cme modify ssh 'Host:"foo* bar*" ForwardX11=yes HostName="" - Host:baz HostName=""'

Note the '-' used to go up one node before "Host:baz". In this case, "up one node" leads to the "root node", so "!" could also be used instead of "-":

 cme modify ssh 'Host:"foo* bar*" ForwardX11=yes HostName="" ! Host:baz HostName=""'

Let's modify now the host name of using a .org domain instead of .com. The :~ operator uses a regexp to loop over several Host entries:

 cme modify ssh 'Host:~/ba[rz]/ HostName=~s/.com$/.org/'

Now that ssh config is mucked up with dummy entries, let's clean up:

 cme modify ssh 'Host:-"baz" Host:-"foo* bar*"'



Load data into the node tree (from the node passed with node) and fill values as we go following the instructions passed with steps. (steps can also be an array ref).

Parameters are:

steps (or step)

A string or an array ref containing the steps to load. See "load string syntax" in above for a description of the string.


Whether to check values while loading. Either yes (default), no or skip. Bad values are discarded when check is set to skip.


Change the target of the ! command: when set, the ! command go to caller node instead of going to root node. (default is false)


Dominique Dumont, (ddumont at cpan dot org)




Dominique Dumont


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