NAME

NAME
Brannigan - Comprehensive, flexible system for validating and parsing
input, mainly targeted at web applications.

SYNOPSIS
use Brannigan;

my %scheme1 = ( name => 'scheme1', params => ... );
my %scheme2 = ( name => 'scheme2', params => ... );
my %scheme3 = ( name => 'scheme3', params => ... );

# use the OO interface
my $b = Brannigan->new(\%scheme1, \%scheme2);
$b->add_scheme(\%scheme3);

my $parsed = $b->process('scheme1', \%params);
if ($parsed->{_rejects}) {
die $parsed->{_rejects};
} else {
return $parsed;
}

# Or use the functional interface
my $parsed = Brannigan::process(\%scheme1, \%params);
if ($parsed->{_rejects}) {
die $parsed->{_rejects};
} else {
return $parsed;
}

For a more comprehensive example, see "MANUAL" in this document or the
Brannigan::Examples document.

DESCRIPTION
Brannigan is an attempt to ease the pain of collecting, validating and
parsing input parameters in web applications. It's designed to answer
both of the main problems that web applications face:

* Simple user input

Brannigan can validate and parse simple, "flat", user input, possibly
coming from web forms.

* Complex data structures

Brannigan can validate and parse complex data structures, possibly
deserialized from JSON or XML data sent to web services and APIs.

Brannigan's approach to data validation is as follows: define a
structure of parameters and their needed validations, and let the module
automatically examine input parameters against this structure. Brannigan
provides you with common validation methods that are used everywhere,
and also allows you to create custom validations easily. This structure
also defines how, if at all, the input should be parsed. This is akin to
schema-based validations such as XSD, but much more functional, and most
of all flexible.

Check the next section for an example of such a structure. I call this
structure a validation/parsing scheme. Schemes can inherit all the
properties of other schemes, which allows you to be much more flexible
in certain situations. Imagine you have a blogging application. A base
scheme might define all validations and parsing needed to create a new
blog post from a user's input. When editing a post, however, some
parameters that were required when creating the post might not be
required now (so you can just use older values), and maybe new
parameters are introduced. Inheritance helps you avoid repeating
yourself. You can another scheme which gets all the properties of the
base scheme, only changing whatever it is needs changing (and possibly
adding specific properties that don't exist in the base scheme).

MANUAL
In the following manual, we will look at the following example. It is
based on Catalyst, but should be fairly understandable for non-Catalyst
users. Do not be alarmed by the size of this, this is only because it
displays basically every aspect of Brannigan.

This example uses Catalyst, but should be pretty self explanatory. It's
fairly complex, since it details pretty much all of the available
Brannigan functionality, so don't be alarmed by the size of this thing.

package MyApp::Controller::Post;

use strict;
use warnings;
use Brannigan;

# create a new Brannigan object with two validation/parsing schemes:
my $b = Brannigan->new({
name => 'post',
ignore_missing => 1,
params => {
subject => {
required => 1,
length_between => [3, 40],
},
text => {
required => 1,
min_length => 10,
validate => sub {
my $value = shift;

return undef unless $value;

return $value =~ m/^lorem ipsum/ ? 1 : undef;
}
},
day => {
required => 0,
integer => 1,
value_between => [1, 31],
},
mon => {
required => 0,
integer => 1,
value_between => [1, 12],
},
year => {
required => 0,
integer => 1,
value_between => [1900, 2900],
},
section => {
required => 1,
integer => 1,
value_between => [1, 3],
parse => sub {
my $val = shift;

my $ret = $val == 1 ? 'reviews' :
$val == 2 ? 'receips' :
'general';

return { section => $ret };
},
},
id => {
required => 1,
exact_length => 10,
value_between => [1000000000, 2000000000],
},
'/^picture_(\d+)$/' => {
length_between => [3, 100],
validate => sub {
my ($value, $num) = @_;

...
},
},
picture_1 => {
default => 'http://www.example.com/avatar.png',
},
array_of_ints => {
array => 1,
min_length => 3,
values => {
integer => 1,
},
},
hash_of_langs => {
hash => 1,
keys => {
_all => {
exact_length => 10,
},
en => {
required => 1,
},
},
},
},
groups => {
date => {
params => [qw/year mon day/],
parse => sub {
my ($year, $mon, $day) = @_;
return undef unless $year && $mon && $day;
return { date => $year.'-'.$mon.'-'.$day };
},
},
tags => {
regex => '/^tags_(en|he|fr)$/',
forbid_words => ['bad_word', 'very_bad_word'],
parse => sub {
return { tags => \@_ };
},
},
},
}, {
name => 'edit_post',
inherits_from => 'post',
params => {
subject => {
required => 0, # subject is no longer required
},
id => {
forbidden => 1,
},
},
});

# create the custom 'forbid_words' validation method
$b->custom_validation('forbid_words', sub {
my $value = shift;

foreach (@_) {
return 0 if $value =~ m/$_/;
}

return 1;
});

# post a new blog post
sub new_post : Local {
my ($self, $c) = @_;

# get input parameters hash-ref
my $params = $c->request->params;

# process the parameters
my $parsed_params = $b->process('post', $params);

if ($parsed_params->{_rejects}) {
die $c->list_errors($parsed_params);
} else {
$c->model('DB::BlogPost')->create($parsed_params);
}
}

# edit a blog post
sub edit_post : Local {
my ($self, $c, $id) = @_;

my $params = $b->process('edit_posts', $c->req->params);

if ($params->{_rejects}) {
die $c->list_errors($params);
} else {
$c->model('DB::BlogPosts')->find($id)->update($params);
}
}

HOW BRANNIGAN WORKS
In essence, Brannigan works in three stages (which all boil down to one
single command):

* Input stage and preparation

Brannigan receives a hash-ref of input parameters, or a hash-ref
based data structure, and the name of a scheme to validate against.
Brannigan then loads the scheme and prepares it (by merging it with
inherited schemes) for later processing.

* Data validation

Brannigan invokes all validation methods defined in the scheme on
the input data, and generates a hash-ref of rejected parameters. For
every parameter in this hash-ref, a list of failed validations is
created in an array-ref.

* Data parsing

Regardless of the previous stage, every parsing method defined in
the scheme is applied on the relevant data. The data resulting from
these parsing methods, along with the values of all input parameters
for which no parsing methods were defined, is returned to the user
in a hash-ref. This hash-ref also includes a _rejects key whose
value is the rejects hash created in the previous stage.

The reason I say this stage isn't dependant on the previous stage is
simple. First of all, it's possible no parameters failed validation,
but the truth is this stage doesn't care if a parameter failed
validation. It will still parse it and return it to the user, and no
errors are ever raised by Brannigan. It is the developer's (i.e.
you) job to decide what to do in case rejects are present.

HOW SCHEMES LOOK
The validation/parsing scheme defines the structure of the data you're
expecting to receive, along with information about the way it should be
validated and parsed. Schemes are created by passing them to the
Brannigan constructor. You can pass as many schemes as you like, and
these schemes can inherit from one another. You can create the Brannigan
object that gets these schemes wherever you want. Maybe in a controller
of your web app that will directly use this object to validate and parse
input it gets, or maybe in a special validation class that will hold all
schemes. It doesn't matter where, as long as you make the object
available for your application.

A scheme is a hash-ref based data structure that has the following keys:

* name

Defines the name of the scheme. Required.

* ignore_missing

Boolean value indicating whether input parameters that are not
referenced in the scheme should be added to the parsed output or
not. Optional, defaults to false (i.e. parameters missing from the
scheme will be added to the output as-is). You might find it is
probably a good idea to turn this on, so any input parameters you're
not expecting to receive from users are ignored.

* inherits_from

Either a scalar naming a different scheme or an array-ref of scheme
names. The new scheme will inherit all the properties of the
scheme(s) defined by this key. If an array-ref is provided, the
scheme will inherit their properties in the order they are defined.
See the "CAVEATS" section for some "heads-up" about inheritance.

* params

The params key is the most important part of the scheme, as it
defines the expected input. This key takes a hash-ref containing the
names of input parameters. Every such name (i.e. key) in itself is
also a hash-ref. This hash-ref defines the necessary validation
methods to assert for this parameter, and optionally a 'parse' and
'default' method. The idea is this: use the name of the validation
method as the key, and the appropriate values for this method as the
value of this key. For example, if a certain parameter, let's say
'subject', must be between 3 to 10 characters long, then your scheme
will contain:

subject => {
length_between => [3, 10]
}

The 'subject' parameter's value (from the user input), along with
both of the values defined above (3 and 10) will be passed to the
"length_between()" validation method. Now, suppose a certain subject
sent to your app failed the "length_between()" validation; then the
rejects hash-ref described earlier will have something like this:

subject => ['length_between(3, 10)']

Notice the values of the "length_between()" validation method were
added to the string, so you can easily know why the parameter failed
the validation.

Custom validation methods: Aside for the built-in validation methods
that come with Brannigan, a custom validation method can be defined
for each parameter. This is done by adding a 'validate' key to the
parameter, and an anonymous subroutine as the value. As with
built-in methods, the parameter's value will be automatically sent
to this method. So, for example, if the subject parameter from above
must start with the words 'lorem ipsum', then we can define the
subject parameter like so:

subject => {
length_between => [3, 10],
validate => sub {
my $value = shift;

return $value =~ m/^lorem ipsum/ ? 1 : 0;
}
}

Custom validation methods, just like built-in ones, are expected to
return a true value if the parameter passed the validation, or a
false value otherwise. If a parameter failed a custom validation
method, then 'validate' will be added to the list of failed
validations for this parameter. So, in our 'subject' example, the
rejects hash-ref will have something like this:

subject => ['length_between(3, 10)', 'validate']

Default values: For your convenience, Brannigan allows you to set
default values for parameters that are not required (so, if you set
a default value for a parameter, don't add the "required()"
validation method to it). There are two ways to add a default value:
either directly, or through an anonymous subroutine (just like the
custom validation method). For example, maybe we'd like the
'subject' parameter to have a default value of 'lorem ipsum dolor
sit amet'. Then we can have the following definition:

subject => {
length_between => [3, 10],
validate => sub {
my $value = shift;

return $value =~ m/^lorem ipsum/ ? 1 : 0;
},
default => 'lorem ipsum dolor sit amet'
}

Alternatively, you can give a parameter a generated default value by
using an anonymous subroutine, like so:

subject => {
length_between => [3, 10],
validate => sub {
my $value = shift;

return $value =~ m/^lorem ipsum/ ? 1 : 0;
},
default => sub {
return int(rand(100000000));
}
}

Notice that default values are added to missing parameters only at
the parsing stage (i.e. stage 3 - after the validation stage), so
validation methods do not apply to default values.

Parse methods: It is more than possible that the way input
parameters are passed to your application will not be exactly the
way you'll eventually use them. That's where parsing methods can
come in handy. Brannigan doesn't have any built-in parsing methods
(obviously), so you must create these by yourself, just like custom
validation methods. All you need to do is add a 'parse' key to the
parameter's definition, with an anonymous subroutine. This
subroutine also receives the value of the parameter automatically,
and is expected to return a hash-ref of key-value pairs. You will
probably find it that most of the time this hash-ref will only
contain one key-value pair, and that the key will probably just be
the name of the parameter. But note that when a parse method exists,
Brannigan makes absolutely no assumptions of what else to do with
that parameter, so you must tell it exactly how to return it. After
all parameters were parsed by Brannigan, all these little hash-refs
are merged into one hash-ref that is returned to the caller. If a
parse method doesn't exist for a paramter, Brannigan will simply add
it "as-is" to the resulting hash-ref. Returning to our subject
example (which we defined must start with 'lorem ipsum'), let's say
we want to substitute 'lorem ipsum' with 'effing awesome' before
using this parameter. Then the subject definition will now look like
this:

subject => {
length_between => [3, 10],
validate => sub {
my $value = shift;

return $value =~ m/^lorem ipsum/ ? 1 : 0;
},
default => 'lorem ipsum dolor sit amet',
parse => sub {
my $value = shift;

$value =~ s/^lorem ipsum/effing awesome/;

return { subject => $value };
}
}

If you're still not sure what happens when no parse method exists,
then you can imagine Brannigan uses the following default parse
method:

param => {
parse => sub {
my $value = shift;

return { param => $value };
}
}

Regular expressions: As of version 0.3, parameter names can also be
regular expressions in the form '/regex/'. Sometimes you cannot know
the names of all parameters passed to your app. For example, you
might have a dynamic web form which starts with a single field
called 'url_1', but your app allows your visitors to dynamically add
more fields, such as 'url_2', 'url_3', etc. Regular expressions are
handy in such situations. Your parameter key can be '/^url_(\d+)$/',
and all such fields will be matched. Regex params have a special
feature: if your regex uses capturing, then captured values will be
passed to the custom "validate" and "parse" methods (in their order)
after the parameter's value. For example:

'/^url_(\d+)$/' => {
validate => sub {
my ($value, $num) = @_;

# $num has the value captured by (\d+) in the regex

return $value =~ m!^http://! ? 1 : undef;
},
parse => sub {
my ($value, $num) = @_;

return { urls => { $num => $value } };
},
}

Please note that a regex must be defined with a starting and
trailing slash, in single quotes, otherwise it won't work. It is
also important to note what happens when a parameter matches a regex
rule (or perhaps rules), and also has a direct reference in the
scheme. For example, let's say we have the following rules in our
scheme:

'/^sub(ject|headline)$/' => {
required => 1,
length_between => [3, 10],
},
subject => {
required => 0,
}

When validating and parsing the 'subject' parameter, Brannigan will
automatically merge both of these references to the subject
parameter, giving preference to the direct reference, so the actual
structure on which the parameter will be validated is as follows:

subject => {
required => 0,
length_between => [3, 10],
}

If your parameter matches more than one regex rule, they will all be
merged, but there's no way (yet) to ensure in which order these
regex rules will be merged.

Complex data structures: As previously stated, Brannigan can also
validate and parse a little more complex data structures. So, your
parameter no longer has to be just a string or a number, but maybe a
hash-ref or an array-ref. In the first case, you tell Brannigan the
paramter is a hash-ref by adding a 'hash' key with a true value, and
a 'keys' key with a hash-ref which is just like the 'params'
hash-ref. For example, suppose you're receiving a 'name' parameter
from the user as a hash-ref containing first and last names. That's
how the 'name' parameter might be defined:

name => {
hash => 1,
required => 1,
keys => {
first_name => {
length_between => [3, 10],
},
last_name => {
required => 1,
min_length => 3,
},
}
}

What are we seeing here? We see that the 'name' parameter must be a
hash-ref, that it's required, and that it has two keys: first_name,
whose length must be between 3 to 10 if it's present, and last_name,
which must be 3 characters or more, and must be present.

An array parameter, on the other hand, is a little different.
Similar to hashes, you define the parameter as an array-ref with the
'array' key with a true value, and a 'values' key. This key has a
hash-ref of validation and parse methods that will be applied to
EVERY value inside this array. For example, suppose you're receiving
a 'pictures' parameter from the user as an array-ref containing URLs
to pictures on the web. That's how the 'pictures' parameter might be
defined:

pictures => {
array => 1,
length_between => [1, 5],
values => {
min_length => 3,
validate => sub {
my $value = shift;

return $value =~ m!^http://! ? 1 : 0;
},
},
}

What are we seeing this time? We see that the 'pictures' parameter
must be an array, with no less than one item (i.e. value) and no
more than five items (notice that we're using the same
"length_between()" method from before, but in the context of an
array, it doesn't validate against character count but item count).
We also see that every value in the 'pictures' array must have a
minimum length of three (this time it is characterwise), and must
match 'http://' in its beginning.

Since complex data structures are supported, you can define default
values for parameters that aren't just strings or numbers (or
methods), for example:

complex_param => {
hash => 1,
keys => {
...
},
default => { key1 => 'def1', key2 => 'def2' }
}

What Brannigan returns for such structures when they fail
validations is a little different than before. Instead of an
array-ref of failed validations, Brannigan will return a hash-ref.
This hash-ref might contain a '_self' key with an array-ref of
validations that failed specifically on the 'pictures' parameter
(such as the 'required' validation for the 'name' parameter or the
'length_between' validation for the 'pictures' parameter), and/or
keys for each value in these structures that failed validation. If
it's a hash, then the key will simply be the name of that key. If
it's an array, it will be its index. For example, let's say the
'first_name' key under the 'name' parameter failed the
"length_between(3, 10)" validation method, and that the 'last_name'
key was not present (and hence failed the "required()" validation).
Also, let's say the 'pictures' parameter failed the
"length_between(1, 5)" validation (for the sake of the argument,
let's say it had 6 items instead of the maximum allowed 5), and that
the 2nd item failed the min_length(3) validation, and the 6th item
failed the custom validate method. Then our rejects hash-ref will
have something like this:

name => {
first_name => ['length_between(3, 10)'],
last_name => ['required(1)'],
},
pictures => {
_self => ['length_between(1, 5)'],
1 => ['min_length(3)'],
5 => ['validate'],
}

Notice the '_self' key under 'pictures' and that the numbering of
the items of the 'pictures' array starts at zero (obviously).

The beauty of Brannigan's data structure support is that it's
recursive. So, it's not that a parameter can be a hash-ref and
that's it. Every key in that hash-ref might be in itself a hash-ref,
and every key in that hash-ref might be an array-ref, and every
value in that array-ref might be a hash-ref... well, you get the
idea. How might that look like? Well, just take a look at this:

pictures => {
array => 1,
values => {
hash => 1,
keys => {
filename => {
min_length => 5,
},
source => {
hash => 1,
keys => {
website => {
validate => sub { ... },
},
license => {
one_of => [qw/GPL FDL CC/],
},
},
},
},
},
}

So, we have a pictures array that every value in it is a hash-ref
with a filename key and a source key whose value is a hash-ref with
a website key and a license key.

Local validations: The _all "parameter" can be used in a scheme to
define rules that apply to all of the parameters in a certain level.
This can either be used directly in the 'params' key of the scheme,
or in the 'keys' key of a hash parameter.

_all => {
required => 1
},
subject => {
length_between => [3, 255]
},
text => {
min_length => 10
}

In the above example, both 'subject' and 'text' receive the
"required()" validation methods.

* groups

Groups are very useful to parse parameters that are somehow related
together. This key takes a hash-ref containing the names of the
groups (names are irrelevant, they're more for you). Every group
will also take a hash-ref, with a rule defining which parameters are
members of this group, and a parse method to use with these
parameters (just like our custom parse method from the 'params'
key). This parse method will automatically receive the values of all
the parameters in the group, in the order they were defined.

For example, suppose our app gets a user's birth date by using three
web form fields: day, month and year. And suppose our app saves this
date in a database in the format 'YYYY-MM-DD'. Then we can define a
group, say 'date', that automatically does this. For example:

date => {
params => [qw/year month day/],
parse => sub {
my ($year, $month, $day) = @_;

$month = '0'.$month if $month < 10;
$day = '0'.$day if $day < 10;

return { date => $year.'-'.$month.'-'.$day };
},
}

Alternative to the 'params' key, you can define a 'regex' key that
takes a regex. All parameters whose name matches this regex will be
parsed as a group. As oppose to using regexes in the 'params' key of
the scheme, captured values in the regexes will not be passed to the
parse method, only the values of the parameters will. Also, please
note that there's no way to know in which order the values will be
provided when using regexes for groups.

For example, let's say our app receives one or more URLs (to
whatever type of resource) in the input, in parameters named
'url_1', 'url_2', 'url_3' and so on, and that there's no limit on
the number of such parameters we can receive. Now, suppose we want
to create an array of all of these URLs, possibly to push it to a
database. Then we can create a 'urls' group such as this:

urls => {
regex => '/^url_(\d+)$/',
parse => sub {
my @urls = @_;

return { urls => \@urls };
}
}

BUILT-IN VALIDATION METHODS
As mentioned earlier, Brannigan comes with a set of built-in validation
methods which are most common and useful everywhere. For a list of all
validation methods provided by Brannigan, check Brannigan::Validations.

CROSS-SCHEME CUSTOM VALIDATION METHODS
Custom "validate" methods are nice, but when you want to use the same
custom validation method in different places inside your scheme, or more
likely in different schemes altogether, repeating the definition of each
custom method in every place you want to use it is not very comfortable.
Brannigan provides a simple mechanism to create custom, named validation
methods that can be used across schemes as if they were internal
methods.

The process is simple: when creating your schemes, give the names of the
custom validation methods and their relevant supplement values as with
every built-in validation method. For example, suppose we want to create
a custom validation method named 'forbid_words', that makes sure a
certain text does not contain any words we don't like it to contain.
Suppose this will be true for a parameter named 'text'. Then we define
'text' like so:

text => {
required => 1,
forbid_words => ['curse_word', 'bad_word', 'ugly_word'],
}

As you can see, we have provided the name of our custom method, and the
words we want to forbid. Now we need to actually create this
"forbid_words()" method. We do this after we've created our Brannigan
object, by using the "custom_validation()" method, as in this example:

$b->custom_validation('forbid_words', sub {
my ($value, @forbidden) = @_;

foreach (@forbidden) {
return 0 if $value =~ m/$_/;
}

return 1;
});

We give the "custom_validation()" method the name of our new method, and
an anonymous subroutine, just like in "local" custom validation methods.

And that's it. Now we can use the "forbid_words()" validation method
across our schemes. If a paremeter failed our custom method, it will be
added to the rejects like built-in methods. So, if 'text' failed our new
method, our rejects hash-ref will contain:

text => [ 'forbid_words(curse_word, bad_word, ugly_word)' ]

As an added bonus, you can use this mechanism to override Brannigan's
built-in validations. Just give the name of the validation method you
wish to override, along with the new code for this method. Brannigan
gives precedence to cross-scheme custom validations, so your method will
be used instead of the internal one.

NOTES ABOUT PARSE METHODS
As stated earlier, your "parse()" methods are expected to return a
hash-ref of key-value pairs. Brannigan collects all of these key-value
pairs and merges them into one big hash-ref (along with all the
non-parsed parameters).

Brannigan actually allows you to have your "parse()" methods be
two-leveled. This means that a value in a key-value pair in itself can
be a hash-ref or an array-ref. This allows you to use the same key in
different places, and Brannigan will automatically aggregate all of
these occurrences, just like in the first level. So, for example,
suppose your scheme has a regex rule that matches parameters like
'tag_en' and 'tag_he'. Your parse method might return something like "{
tags => { en => 'an english tag' } }" when it matches the 'tag_en'
parameter, and something like "{ tags => { he => 'a hebrew tag' } }"
when it matches the 'tag_he' parameter. The resulting hash-ref from the
process method will thus include "{ tags => { en => 'an english tag', he
=> 'a hebrew tag' } }".

Similarly, let's say your scheme has a regex rule that matches
parameters like 'url_1', 'url_2', etc. Your parse method might return
something like "{ urls => [$url_1] }" for 'url_1' and "{ urls =>
[$url_2] }" for 'url_2'. The resulting hash-ref in this case will be "{
urls => [$url_1, $url_2] }".

Take note however that only two-levels are supported, so don't go crazy
with this.

SO HOW DO I PROCESS INPUT?
OK, so we have created our scheme(s), we know how schemes look and work,
but what now?

Well, that's the easy part. All you need to do is call the "process()"
method on the Brannigan object, passing it the name of the scheme to
enforce and a hash-ref of the input parameters/data structure. This
method will return a hash-ref back, with all the parameters after
parsing. If any validations failed, this hash-ref will have a '_rejects'
key, with the rejects hash-ref described earlier. Remember: Brannigan
doesn't raise any errors. It's your job to decide what to do, and that's
a good thing.

Example schemes, input and output can be seen in Brannigan::Examples.

CONSTRUCTOR
new( \%scheme | @schemes )
Creates a new instance of Brannigan, with the provided scheme(s) (see
"HOW SCHEMES LOOK" for more info on schemes).

OBJECT METHODS
add_scheme( \%scheme | @schemes )
Adds one or more schemes to the object. Every scheme hash-ref should
have a "name" key with the name of the scheme. Existing schemes will be
overridden. Returns the object itself for chainability.

process( $scheme, \%params )
Receives the name of a scheme and a hash-ref of input parameters (or a
data structure), and validates and parses these paremeters according to
the scheme (see "HOW SCHEMES LOOK" for detailed information about this
process).

Returns a hash-ref of parsed parameters according to the parsing scheme,
possibly containing a list of failed validations for each parameter.

Actual processing is done by Brannigan::Tree.

process( \%scheme, \%params )
Same as above, but takes a scheme hash-ref instead of a name hash-ref.
That basically gives you a functional interface for Brannigan, so you
don't have to go through the regular object oriented interface. The only
downsides to this are that you cannot define custom validations using
the "custom_validation()" method (defined below) and that your scheme
must be standalone (it cannot inherit from other schemes). Note that
when directly passing a scheme, you don't need to give the scheme a
name.

custom_validation( $name, $code )
Receives the name of a custom validation method ($name), and a reference
to an anonymous subroutine ($code), and creates a new validation method
with that name and code, to be used across schemes in the Brannigan
object as if they were internal methods. You can even use this to
override internal validation methods, just give the name of the method
you want to override and the new code.

CAVEATS
Brannigan is still in an early stage. Currently, no checks are made to
validate the schemes built, so if you incorrectly define your schemes,
Brannigan will not croak and processing will probably fail. Also, there
is no support yet for recursive inheritance or any crazy inheritance
situation. While deep inheritance is supported, it hasn't been tested
extensively. Also bugs are popping up as I go along, so keep in mind
that you might encounter bugs (and please report any if that happens).

IDEAS FOR THE FUTURE
The following list of ideas may or may not be implemented in future
versions of Brannigan:

* Cross-scheme custom parsing methods

Add an option to define custom parse methods in the Brannigan object
that can be used in the schemes as if they were built-in methods
(cross-scheme custom validations are already supported, next up is
parse methods).

* Support for third-party validation methods

Add support for loading validation methods defined in third-party
modules (written like Brannigan::Validations) and using them in
schemes as if they were built-in methods.

* Validate schemes by yourself

Have Brannigan use itself to validate the schemes it receives from
the developers (i.e. users of this module).

* Support loading schemes from JSON/XML

Allow loading schemes from JSON/XML files or any other source. Does
that make any sense?

* Something to aid rejects traversal

Find something that would make traversal of the rejects list easier
or whatever. Plus, printing the name of the validation method and
its supplement values in the rejects list isn't always a good idea.
For example, if we use the "one_of()" validation method with a big
list of say 100 options, our rejects list will contain all these 100
options, and that's not nice. So, think about something there.

SEE ALSO
Brannigan::Validations, Brannigan::Tree, Brannigan::Examples.

AUTHOR
Ido Perlmuter, "<ido at ido50 dot net>"

BUGS
Please report any bugs or feature requests to "bug-brannigan at
rt.cpan.org", or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Brannigan>. I will be
notified, and then you'll automatically be notified of progress on your
bug as I make changes.

SUPPORT
You can find documentation for this module with the perldoc command.

perldoc Brannigan

You can also look for information at:

* RT: CPAN's request tracker

<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Brannigan>

* AnnoCPAN: Annotated CPAN documentation

<http://annocpan.org/dist/Brannigan>

* CPAN Ratings

<http://cpanratings.perl.org/d/Brannigan>

* Search CPAN

<http://search.cpan.org/dist/Brannigan/>

ACKNOWLEDGEMENTS
Brannigan was inspired by Oogly (Al Newkirk) and the "Ketchup" jQuery
validation plugin (<http://demos.usejquery.com/ketchup-plugin/>).

LICENSE AND COPYRIGHT
Copyright 2017 Ido Perlmuter

Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.