NAME

Config::Validate - Validate data structures generated from configuration files. (Or anywhere else)

VERSION

Version 0.2.6

DESCRIPTION

This module is for validating configuration data that has been read in already and is in a Perl data structure. It does not handle reading or parsing configuration files since there are a plethora of available modules on CPAN to do that task. Instead it concentrates on verifying that the data read is correct, and providing defaults where appropriate. It also allows you to specify that a given configuration key may be available under several aliases, and have those renamed to the canonical name automatically.

The basic model used is that the caller provides a schema as a perl data structure that describes the constraints to verify against. The caller can then use the "Config::Validate" object to validate any number of data structures against the configured schema. If the data structure conforms to the schema given, then a new data structure will be returned, otherwise an exception is thrown.

Probably the easiest way to explain the intent is that "Config::Validate" is trying to be like "Params::Validate" for configuration files and other data structures.

This module has the following features:

• Data structure depth is only limited by stack depth
• Can provide defaults for missing items at any level of the data structure.
• Can require that items exist, or items can be optional.
• Can validate items in the data structure against a number of built in data types, and users can easily add more data types.
• Configuration keys can be known by several names, and will be normalized to the canonical name in the data structure returned by the validation.

SCHEMA DEFINITION

The most complex part of using "Config::Validate" is defining the schema to validate against. The schema takes the form of set of nested hashes.

Here is an example schema you might use if you were writing something that needs to validate a database connection configuration file.

      my $schema = { db => { 
                        type => 'nested',
                        alias => 'dbinfo',
                        child => { 
                           hostname => { 
                              type => 'hostname'
                              alias => [ qw(host server) ],
                              default => 'localhost,
                           },
                           port => { 
                              type => 'integer',
                              max => 64*1024 - 1,
                              min => 1,
                              default => '3306',
                           },
                           username => { 
                              type => 'string'
                              optional => 1,
                              alias => 'user',
                           },
                           password => { 
                              type => 'string',
                              optional => 1,
                              alias => [ qw(pass passwd) ],
                           },
                           database => {
                              type => 'string',
                              alias => 'dbname',
                           },
                           column_types => {
                              type => 'hash',
                              keytype => 'string',
                              child => {
                                id => { 
                                   type => 'string',
                                   default => 'INT',
                              },
                           },
                        },
                     allowed_users => {
                        type => 'array',
                        subtype => 'string',
                     },
                  };

This is a somewhat long example of what a schema can look like. This uses most of the features available. The basic format is that a schema consists of a hash of hashes. Each of it's children describe a single field in the data structure to be validated. The only required key in the field definition is "type", which defines how that element in the data/config hash should be validated.

VALIDATION TYPES
Below is a list of the built in validation types, and the options they take. There are several global options that any of these can take that are documented below.

nested
The "nested" type provides a way to validate nested hash references. Valid options are:

• child Hash reference that defines all the valid keys and values in the

  nested section. Required.

integer
The "integer" type expects a whole number that can be positive or negative. Valid options are:

• min Smallest valid value
• max Largest valid value

float
The "float" type verifies that the value meets the "looks_like_number" test from Scalar::Util. Valid options are:

• min Smallest valid value
• max Largest valid value

string
The "string" type does no validation if no addition restrictions are specified. Valid options are:

• min Minimum length
• max Maximum length
• regex String must match the regex provided.

boolean
The "boolean" type looks for a number of specific values, and converts them to 0 or 1. The values considered to be true are: 1, "y", "yes", "t", "true" and "on". The values considered to be false are 0, "n", "no", "f", "false", "off". These values are not case sensitive. The "boolean" type takes no options.

directory
The "directory" type verifies that the value is a directory that exists. The "directory" type takes no options.

file
The "file" type verifies that the value is a file, or a symlink that points at a file that exists. The "file" type takes no options.

domain
The "domain" type uses the Data::Validate::Domain "is_domain" function to verify that the value is a validate domain name. This does not look the value up in DNS and verify that it exists. The "domain" type takes no options.

hostname
The "hostname" type uses the Data::Validate::Domain "is_hostname" function to verify that the value is a validate hostname name. This does not look the value up in DNS and verify that it exists. The "hostname" type takes no options.

array
The "array" type verifies that the value is an array reference. If the "array_allows_scalar" option is turned on (it is by default), then if a scalar value is found, then it will automatically be converted to an array reference with a single element.

• subkey

  Required option that specifies the type of the elements of the array.

hash
The "hash" type validates a hash reference of key/value pairs.

• keytype

  Required option that specifies the type of validation to do on hash keys

• child If the "hash" type finds a "child" option, then it will validate

  any keys in the hash against the fields in the "child" definition. Note that it is NOT an error if elements are found in the hash that are not in child. If you want that behavior, you should use the "nested" type instead.

COMMON OPTIONS
There are a set of options that can be added to any field definition, that provide a common set of functionality to all.

• alias The "alias" option allows you to specify other names that a

  particular field might be known by. For example, you may have a field named "password", but also want to accept "pass", "passwd" and "pw". If any of the aliases are found, then they will be renamed in the data structure that is returned by "validate". This option can point to a scalar, or an array reference.

• callback

  The "callback" option allows you to specify a callback that will be called after any other validation has been done for a specific field in the data structure. The callback sub is called with a reference to the "Config::Validate" object (one is created automatically if you're using the functional interface), the value to be verified, the definition of the field, and an array reference containing the path into the data structure. You can use the "mkpath" method to convert the path to a more readable form for error messages and such.

• default

  The "default" option allows you to specify a default for the field. This implicitly means the field is not required to exist in the data structure being validated. As many levels as necessary will be created in the resulting data structure to insure the default is created.

• optional

  If the "optional" option is true, then the field is not required. If "optional" is false, or not defined, then the field is required.

SUBROUTINES/METHODS
new
The new method constructs a "Config::Validate" object, and returns it. It accepts the following arguments:

• schema

  A validation schema as described in the "SCHEMA DEFINITION" section above.

• data_path

  If this is set to true, and the "Data::Path" module is available, then the "validate" method/function will encapsulate the results returned in a "Data::Path" instance. Defaults to false;

• data_path_options

  If the "data_path" option is true, then this should be a hash reference to be passed in as the second argument to the "Data:Path" constructor.

• array_allows_scalar

  If this is true, then scalars will be autopromoted to a single element array reference when validating "array" types.

• debug Enables debugging output.
• on_debug

  Allows you to define a callback for debugging output. A default callback will be provided if this isn't set. The default callback simply prints the debug output to STDOUT. If you set the callback, then will be called with the object as the first parameter, and the additional parameters should be joined to form the entire message.

In addition, any of these can read or changed after the object is created, via an accessor with the same name as the parameter.

validate
The validate sub can be called as either a function, or as a instance method.

If it is called as an instance method, then it expects a single "config" parameter which should be the data structure/config to be validated.

my $result = $obj->validate(config => $config)

If it is called as a function, then it accepts two parameters. The "config" parameter should be the data structure/config to be validated, and the "schema" parameter should be the schema.

my $result = validate(config => $config, schema => $schema)

The "config" parameter above can be a hash reference, or it can be a "Config::General" object. If it is a "Config::General" object, then the validate sub will automatically call the "getall" method on the object.

If any errors are encountered, then the validate sub will call die to throw an exception. In that case the value of $@ contain an error message describing the problem.

There was formerly a one and two argument variant of this sub. It is still supported, but deprecated.

add_type
The "add_type" method allows you to register a validation type on just a single instance of "Config::Validate". The parameters are as follows:

• name This is the name to be specified in the schema to use this

  validation type. This is a mandatory parameter.

• validate

  The value of "validate" should be a callback that will be run when it is necessary to validate a field of this type. The callback will be passed the "Config::Validate" object, the name of the field being validated, the schema definition of that field, and an array reference containing the path into the data structure. You can use the "mkpath" method to convert the path to a more readable form for error messages and such.

• init The value of "init" should be a callback that will be run before

  any validation is done. The callback will be passed the "Config::Validate" object, the schema, and the configuration being validated.

• finish

  The value of "finish" should be a callback that will be run after any validation is done. The callback will be passed the "Config::Validate" object, the schema, and the configuration being validated.

add_default_type
The "add_default_type" method allows you to register a validation type for all new "Config::Validate" instances. It can be called as a function, class method, or instance method. If it is called as an instance method, then the new type will also be added to that instance. The parameters are the same as "add_type".

reset_default_types
The "reset_default_types" method removes all user defined types from the base class. Any instances that are alread created will retain their existing type configuration.

mkpath
This is a convenience function for people writing callbacks and user defined type validation. It takes either an array or array reference and returns a string that represents the path to a specific item in the configuration. This might be useful if you're interested in having your error messages be consistent with the rest of "Config::Validate". This is available for export, but not exported by default. Note: this is a function, not a method.

AUTHOR

Clayton O'Neill

Eval for e-mail address: "join('@', join('.', qw(cv 20 coneill)), 'xoxy.net')"

LICENSE AND COPYRIGHT

Copyright (C) 2007-2008 by Clayton O'Neill

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.5 or, at your option, any later version of Perl 5 you may have available.