Clayton O'Neill
and 1 contributors

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.