The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.
 / 
Config-Model-2.071
River stage two • 11 direct dependents • 11 total dependents
3 ++
/ Config::Model::Node

NAME

Config::Model::Node - Class for configuration tree node

VERSION

version 2.071

SYNOPSIS

 use Config::Model;
 use Log::Log4perl qw(:easy);
 Log::Log4perl->easy_init($WARN);

 # define configuration tree object
 my $model = Config::Model->new;
 $model->create_config_class(
    name              => 'OneConfigClass',
    class_description => "OneConfigClass detailed description",

    element => [
        [qw/X Y Z/] => {
            type       => 'leaf',
            value_type => 'enum',
            choice     => [qw/Av Bv Cv/]
        }
    ],

    status      => [ X => 'deprecated' ],
    description => [ X => 'X-ray description (can be long)' ],
    summary     => [ X => 'X-ray' ],

    accept => [
        'ip.*' => {
            type       => 'leaf',
            value_type => 'uniline',
            summary    => 'ip address',
        }
    ]
 );
 my $instance = $model->instance (root_class_name => 'OneConfigClass');
 my $root = $instance->config_root ;

 # X is not shown below because of its deprecated status
 print $root->describe,"\n" ;
 # name         value        type         comment
 # Y            [undef]      enum         choice: Av Bv Cv
 # Z            [undef]      enum         choice: Av Bv Cv

 # add some data
 $root->load( step => 'Y=Av' );

 # add some accepted element, ipA and ipB are created on the fly
 $root->load( step => q!ipA=192.168.1.0 ipB=192.168.1.1"! );

 # show also ip* element created in the last "load" call
 print $root->describe,"\n" ;
 # name         value        type         comment
 # Y            Av           enum         choice: Av Bv Cv
 # Z            [undef]      enum         choice: Av Bv Cv
 # ipA          192.168.1.0  uniline
 # ipB          192.168.1.1  uniline

DESCRIPTION

This class provides the nodes of a configuration tree. When created, a node object will get a set of rules that will define its properties within the configuration tree.

Each node contain a set of elements. An element can contain:

  • A leaf element implemented with Config::Model::Value. A leaf can be plain (unconstrained value) or be strongly typed (values are checked against a set of rules).

  • Another node.

  • A collection of items: a list element, implemented with Config::Model::ListId. Each item can be another node or a leaf.

  • A collection of identified items: a hash element, implemented with Config::Model::HashId. Each item can be another node or a leaf.

Configuration class declaration

A class declaration is made of the following parameters:

name

Mandatory string parameter. This config class name can be used by a node element in another configuration class.

class_description

Optional string parameter. This description will be used when generating user interfaces.

class

Optional string to specify a Perl class to override the default implementation (Config::Model::Node). This Perl Class must inherit Config::Model::Node. Use with care.

element

Mandatory list ref of elements of the configuration class :

  element => [ foo => { type = 'leaf', ... },
               bar => { type = 'leaf', ... }
             ]

Element names can be grouped to save typing:

  element => [ [qw/foo bar/] => { type = 'leaf', ... } ]

See below for details on element declaration.

level

Optional list ref of the elements whose level are different from default value (normal). Possible values are important, normal or hidden.

The level is used to set how configuration data is presented to the user in browsing mode. Important elements will be shown to the user no matter what. hidden elements will be explained with the warp notion.

  level  => [ [qw/X Y/] => 'important' ]
status

Optional list ref of the elements whose status are different from default value (standard). Possible values are obsolete, deprecated or standard.

Using a deprecated element will issue a warning. Using an obsolete element will raise an exception (See Config::Model::Exception.

  status  => [ [qw/X Y/] => 'obsolete' ]
description

Optional list ref of element description. These descriptions will be used when generating user interfaces.

description

Optional list ref of element summary. These descriptions will be used when generating user interfaces or as comment when writing configuration files.

read_config
write_config
config_dir

Parameters used to load on demand configuration data. See Config::Model::BackendMgr for details.

accept

Optional list of criteria (i.e. a regular expression to match ) to accept unknown parameters. Each criteria will have a list of specification that will enable Config::Model to create a model snippet for the unknown element.

Example:

 accept => [
    'list.*' => {
        type  => 'list',
        cargo => {
            type       => 'leaf',
            value_type => 'string',
        },
    },
    'str.*' => {
        type       => 'leaf',
        value_type => 'uniline'
    },
  ]

All element parameters can be used in specifying accepted parameters.

The parameter accept_after to specify where to insert the accepted element. This will not change much the behavior of the tree, but it will help generate user interface easier to use.

Example:

 element => [
    'Bug' => { type => 'leaf', value_type => 'uniline' } ,
 ]
 accept => [
    'Bug-.*' =>  {
         value_type => 'uniline',
         type => 'leaf'
         accept_after => 'Bug' ,
    }
 ]

The model snippet above will ensure that Bug-Debian will be shown right after bug.

For more information, see this blog.

Element declaration

Element type

Each element is declared with a list ref that contains all necessary information:

  element => [
               foo => { ... }
             ]

This most important information from this hash ref is the mandatory type parameter. The type type can be:

node

The element is a simple node of a tree instantiated from a configuration class (declared with "create_config_class( ... )" in Config::Model). See "Node element".

warped_node

The element is a node whose properties (mostly config_class_name) can be changed (warped) according to the values of one or more leaf elements in the configuration tree. See Config::Model::WarpedNode for details.

leaf

The element is a scalar value. See "Leaf element"

hash

The element is a collection of nodes or values (default). Each element of this collection is identified by a string (Just like a regular hash, except that you can set up constraint of the keys). See "Hash element"

list

The element is a collection of nodes or values (default). Each element of this collection is identified by an integer (Just like a regular perl array, except that you can set up constraint of the keys). See "List element"

check_list

The element is a collection of values which are unique in the check_list. See CheckList.

class

Override the default class for leaf, list and hash elements. The override class be inherit Config::Model::Value for leaf element, Config::Model::HashId for hash element and Config::Model::ListId for list element.

Node element

When declaring a node element, you must also provide a config_class_name parameter. For instance:

 $model ->create_config_class
   (
   name => "ClassWithOneNode",
   element => [
                the_node => {
                              type => 'node',
                              config_class_name => 'AnotherClass',
                            },
              ]
   ) ;

Leaf element

When declaring a leaf element, you must also provide a value_type parameter. See Config::Model::Value for more details.

Hash element

When declaring a hash element, you must also provide a index_type parameter.

You can also provide a cargo_type parameter set to node or leaf (default).

See Config::Model::HashId and Config::Model::AnyId for more details.

List element

You can also provide a cargo_type parameter set to node or leaf (default).

See Config::Model::ListId and Config::Model::AnyId for more details.

Introspection methods

name

Returns the location of the node, or its config class name (for root node).

get_type

Returns node.

config_model

Returns the entire configuration model (Config::Model object).

model

Returns the configuration model of this node (data structure).

config_class_name

Returns the configuration class name of this node.

instance

Returns the instance object containing this node. Inherited from Config::Model::AnyThing

has_element ( name => element_name, [ type => searched_type ] )

Returns 1 if the class model has the element declared or if the element name is matched by the optional accept parameter. If type is specified, the element name must also match the type.

find_element ( element_name , [ case => any ])

Returns $name if the class model has the element declared or if the element name is matched by the optional accept parameter.

If case is set to any, has_element will return the element name who match the passed name in a case-insensitive manner.

Returns empty if no matching element is found.

model_searcher ()

Returns an object dedicated to search an element in the configuration model (respecting privilege level).

This method returns a Config::Model::SearchElement object. See Config::Model::SearchElement for details on how to handle a search.

This method is inherited from Config::Model::AnyThing.

element_model ( element_name )

Returns model of the element.

element_type ( element_name )

Returns the type (e.g. leaf, hash, list, checklist or node) of the element.

element_name()

Returns the element name that contain this object. Inherited from Config::Model::AnyThing

index_value()

See "index_value()" in Config::Model::AnyThing

parent()

See "parent()" in Config::Model::AnyThing

root()

See "root()" in Config::Model::AnyThing

location()

See "location()" in Config::Model::AnyThing

Element property management

get_element_name ( ... )

Return all elements names available.

Optional parameters are:

  • type: Returns only element of requested type (e.g. list, hash, leaf,...). By default return elements of any type.

  • cargo_type: Returns only element which contain requested type. E.g. if get_element_name is called with cargo_type => leaf, get_element_name will return simple leaf elements, but also hash or list element that contain leaf object. By default return elements of any type.

  • check: yes, no or skip

Returns an array in array context, and a string (e.g. join(' ',@array)) in scalar context.

children

Like get_element_name without parameters. Returns the list of elements. This method is polymorphic for all non-leaf objects of the configuration tree.

next_element ( ... )

This method provides a way to iterate through the elements of a node. Mandatory parameter is name. Optional parameter: status.

Returns the next element name for status (default normal). Returns undef if no next element is available.

previous_element ( name => element_name )

This method provides a way to iterate through the elements of a node.

Returns the previous element name. Returns undef if no previous element is available.

get_element_property ( element => ..., property => ... )

Retrieve a property of an element.

I.e. for a model :

  status     => [ X => 'deprecated' ]
  element    => [ X => { ... } ]

This call will return deprecated:

  $node->get_element_property ( element => 'X', property => 'status' )

set_element_property ( element => ..., property => ... )

Set a property of an element.

reset_element_property ( element => ... )

Reset a property of an element according to the original model.

Information management

fetch_element ( name => .. , [ check => ..] )

Fetch and returns an element from a node.

check can be set to yes, no or skip. When check is no or skip, can return undef when the element is unknown, or 0 if the element is not available (hidden).

fetch_element_value ( name => ... [ check => ...] )

Fetch and returns the value of a leaf element from a node.

store_element_value ( name, value )

Store a value in a leaf element from a node.

Can be invoked with named parameters (name, value, check)

is_element_available( name => ..., )

Returns 1 if the element name is available and if the element is not "hidden". Returns 0 otherwise.

As a syntactic sugar, this method can be called with only one parameter:

   is_element_available( 'element_name' ) ;

accept_element( name )

Checks and returns the appropriate model of an acceptable element (be it explicitly declared, or part of an accept declaration). Returns undef if the element cannot be accepted.

accept_regexp( name )

Returns the list of regular expressions used to check for acceptable parameters. Useful for diagnostics.

element_exists( element_name )

Returns 1 if the element is known in the model.

is_element_defined( element_name )

Returns 1 if the element is defined.

grab(...)

See "grab(...)" in Config::Model::AnyThing.

grab_value(...)

See "grab_value(...)" in Config::Model::AnyThing.

grab_root()

See "grab_root()" in Config::Model::AnyThing.

get( path => ..., mode => ... , check => ... , get_obj => 1|0, autoadd => 1|0)

Get a value from a directory like path. If get_obj is 1, get will return leaf object instead of returning their value.

set( path , value)

Set a value from a directory like path.

data modification

migrate

Force a read of the configuration and perform all changes regarding deprecated elements or values. Return 1 if data needs to be saved.

apply_fixes

Scan the tree from this node and apply fixes that are attached to warning specifications. See warn_if_match or warn_unless_match in "" in Config::Model::Value.

load ( step => string [ ... ])

Load configuration data from the string into the node and its siblings.

This string follows the syntax defined in Config::Model::Loader. See "load ( ... )" in Config::Model::Loader for details on parameters.

This method can also be called with a single parameter:

  $node->load("some data:to be=loaded");

load_data ( data => hash_ref, [ check => $check, ... ])

Load configuration data with a hash ref. The hash ref key must match the available elements of the node (or accepted element). The hash ref structure must match the structure of the configuration model.

Use check => skip to make data loading more tolerant: bad data will be discarded.

load_data can be called with a single hash ref parameter.

needs_save

return 1 if one of the elements of the node's sub-tree has been modified.

Serialization

dump_tree ( ... )

Dumps the configuration data of the node and its siblings into a string. See "dump_tree" in Config::Model::Dumper for parameter details.

This string follows the syntax defined in Config::Model::Loader. The string produced by dump_tree can be passed to load.

dump_annotations_as_pod ( ... )

Dumps the configuration annotations of the node and its siblings into a string. See "dump_annotations_as_pod" in Config::Model::Dumper for parameter details.

describe ( [ element => ... ] )

Provides a description of the node elements or of one element.

report ()

Provides a text report on the content of the configuration below this node.

audit ()

Provides a text audit on the content of the configuration below this node. This audit will show only value different from their default value.

copy_from ( from => another_node_object, [ check => ... ] )

Copy configuration data from another node into this node and its siblings. The copy can be made in a tolerant mode where invalid data is discarded with check => skip. This method can be called with a single argument: copy_from($another_node)

Help management

get_help ( [ [ description | summary ] => element_name ] )

If called without element, returns the description of the class (Stored in class_description attribute of a node declaration).

If called with an element name, returns the description of the element (Stored in description attribute of a node declaration).

If called with 2 argument, either return the summary or the description of the element.

Returns an empty string if no description was found.

tree_searcher( type => ... )

Returns an object able to search the configuration tree. Parameters are :

type

Where to perform the search. It can be element, value, key, summary, description, help or all.

Typically, you will have to call search on this object.

Returns a Config::Model::TreeSearcher object.

Lazy load of node data

As configuration model are getting bigger, the load time of a tree gets longer. The Config::Model::BackendMgr class provides a way to load the configuration information only when needed.

AUTHOR

Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO

Config::Model, Config::Model::Instance, Config::Model::HashId, Config::Model::ListId, Config::Model::CheckList, Config::Model::WarpedNode, Config::Model::Value

AUTHOR

Dominique Dumont

COPYRIGHT AND LICENSE

This software is Copyright (c) 2015 by Dominique Dumont.

This is free software, licensed under:

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