Params::Check - phpMan

NAME
    Params::Check - A generic input parsing/checking mechanism.

SYNOPSIS
        use Params::Check qw[check allow last_error];

        sub fill_personal_info {
            my %hash = @_;
            my $x;

            my $tmpl = {
                firstname   => { required   => 1, defined => 1 },
                lastname    => { required   => 1, store => \$x },
                gender      => { required   => 1,
                                 allow      => [qr/M/i, qr/F/i],
                               },
                married     => { allow      => [0,1] },
                age         => { default    => 21,
                                 allow      => qr/^\d+$/,
                               },

                phone       => { allow => [ sub { return 1 if /$valid_re/ },
                                            '1-800-PERL' ]
                               },
                id_list     => { default        => [],
                                 strict_type    => 1
                               },
                employer    => { default => 'NSA', no_override => 1 },
            };

            ### check() returns a hashref of parsed args on success ###
            my $parsed_args = check( $tmpl, \%hash, $VERBOSE )
                                or die qw[Could not parse arguments!];

            ... other code here ...
        }

        my $ok = allow( $colour, [qw|blue green yellow|] );

        my $error = Params::Check::last_error();

DESCRIPTION
    Params::Check is a generic input parsing/checking mechanism.

    It allows you to validate input via a template. The only requirement is
    that the arguments must be named.

    Params::Check can do the following things for you:

    *   Convert all keys to lowercase

    *   Check if all required arguments have been provided

    *   Set arguments that have not been provided to the default

    *   Weed out arguments that are not supported and warn about them to the
        user

    *   Validate the arguments given by the user based on strings, regexes,
        lists or even subroutines

    *   Enforce type integrity if required

    Most of Params::Check's power comes from its template, which we'll
    discuss below:

Template
    As you can see in the synopsis, based on your template, the arguments
    provided will be validated.

    The template can take a different set of rules per key that is used.

    The following rules are available:

    default
        This is the default value if none was provided by the user. This is
        also the type "strict_type" will look at when checking type
        integrity (see below).

    required
        A boolean flag that indicates if this argument was a required
        argument. If marked as required and not provided, check() will fail.

    strict_type
        This does a "ref()" check on the argument provided. The "ref" of the
        argument must be the same as the "ref" of the default value for this
        check to pass.

        This is very useful if you insist on taking an array reference as
        argument for example.

    defined
        If this template key is true, enforces that if this key is provided
        by user input, its value is "defined". This just means that the user
        is not allowed to pass "undef" as a value for this key and is
        equivalent to: allow => sub { defined $_[0] && OTHER TESTS }

    no_override
        This allows you to specify "constants" in your template. ie, they
        keys that are not allowed to be altered by the user. It pretty much
        allows you to keep all your "configurable" data in one place; the
        "Params::Check" template.

    store
        This allows you to pass a reference to a scalar, in which the data
        will be stored:

            my $x;
            my $args = check(foo => { default => 1, store => \$x }, $input);

        This is basically shorthand for saying:

            my $args = check( { foo => { default => 1 }, $input );
            my $x    = $args->{foo};

        You can alter the global variable $Params::Check::NO_DUPLICATES to
        control whether the "store"'d key will still be present in your
        result set. See the "Global Variables" section below.

    allow
        A set of criteria used to validate a particular piece of data if it
        has to adhere to particular rules.

        See the "allow()" function for details.

Functions
  check( \%tmpl, \%args, [$verbose] );
    This function is not exported by default, so you'll have to ask for it
    via:

        use Params::Check qw[check];

    or use its fully qualified name instead.

    "check" takes a list of arguments, as follows:

    Template
        This is a hash reference which contains a template as explained in
        the "SYNOPSIS" and "Template" section.

    Arguments
        This is a reference to a hash of named arguments which need
        checking.

    Verbose
        A boolean to indicate whether "check" should be verbose and warn
        about what went wrong in a check or not.

        You can enable this program wide by setting the package variable
        $Params::Check::VERBOSE to a true value. For details, see the
        section on "Global Variables" below.

    "check" will return when it fails, or a hashref with lowercase keys of
    parsed arguments when it succeeds.

    So a typical call to check would look like this:

        my $parsed = check( \%template, \%arguments, $VERBOSE )
                        or warn q[Arguments could not be parsed!];

    A lot of the behaviour of "check()" can be altered by setting package
    variables. See the section on "Global Variables" for details on this.

  allow( $test_me, \@criteria );
    The function that handles the "allow" key in the template is also
    available for independent use.

    The function takes as first argument a key to test against, and as
    second argument any form of criteria that are also allowed by the
    "allow" key in the template.

    You can use the following types of values for allow:

    string
        The provided argument MUST be equal to the string for the validation
        to pass.

    regexp
        The provided argument MUST match the regular expression for the
        validation to pass.

    subroutine
        The provided subroutine MUST return true in order for the validation
        to pass and the argument accepted.

        (This is particularly useful for more complicated data).

    array ref
        The provided argument MUST equal one of the elements of the array
        ref for the validation to pass. An array ref can hold all the above
        values.

    It returns true if the key matched the criteria, or false otherwise.

  last_error()
    Returns a string containing all warnings and errors reported during the
    last time "check" was called.

    This is useful if you want to report then some other way than "carp"'ing
    when the verbose flag is on.

    It is exported upon request.

Global Variables
    The behaviour of Params::Check can be altered by changing the following
    global variables:

  $Params::Check::VERBOSE
    This controls whether Params::Check will issue warnings and explanations
    as to why certain things may have failed. If you set it to 0,
    Params::Check will not output any warnings.

    The default is 1 when warnings are enabled, 0 otherwise;

  $Params::Check::STRICT_TYPE
    This works like the "strict_type" option you can pass to "check", which
    will turn on "strict_type" globally for all calls to "check".

    The default is 0;

  $Params::Check::ALLOW_UNKNOWN
    If you set this flag, unknown options will still be present in the
    return value, rather than filtered out. This is useful if your
    subroutine is only interested in a few arguments, and wants to pass the
    rest on blindly to perhaps another subroutine.

    The default is 0;

  $Params::Check::STRIP_LEADING_DASHES
    If you set this flag, all keys passed in the following manner:

        function( -key => 'val' );

    will have their leading dashes stripped.

  $Params::Check::NO_DUPLICATES
    If set to true, all keys in the template that are marked as to be stored
    in a scalar, will also be removed from the result set.

    Default is false, meaning that when you use "store" as a template key,
    "check" will put it both in the scalar you supplied, as well as in the
    hashref it returns.

  $Params::Check::PRESERVE_CASE
    If set to true, Params::Check will no longer convert all keys from the
    user input to lowercase, but instead expect them to be in the case the
    template provided. This is useful when you want to use similar keys with
    different casing in your templates.

    Understand that this removes the case-insensitivity feature of this
    module.

    Default is 0;

  $Params::Check::ONLY_ALLOW_DEFINED
    If set to true, Params::Check will require all values passed to be
    "defined". If you wish to enable this on a 'per key' basis, use the
    template option "defined" instead.

    Default is 0;

  $Params::Check::SANITY_CHECK_TEMPLATE
    If set to true, Params::Check will sanity check templates, validating
    for errors and unknown keys. Although very useful for debugging, this
    can be somewhat slow in hot-code and large loops.

    To disable this check, set this variable to "false".

    Default is 1;

  $Params::Check::WARNINGS_FATAL
    If set to true, Params::Check will "croak" when an error during template
    validation occurs, rather than return "false".

    Default is 0;

  $Params::Check::CALLER_DEPTH
    This global modifies the argument given to "caller()" by
    "Params::Check::check()" and is useful if you have a custom wrapper
    function around "Params::Check::check()". The value must be an integer,
    indicating the number of wrapper functions inserted between the real
    function call and "Params::Check::check()".

    Example wrapper function, using a custom stacktrace:

        sub check {
            my ($template, $args_in) = @_;

            local $Params::Check::WARNINGS_FATAL = 1;
            local $Params::Check::CALLER_DEPTH = $Params::Check::CALLER_DEPTH + 1;
            my $args_out = Params::Check::check($template, $args_in);

            my_stacktrace(Params::Check::last_error) unless $args_out;

            return $args_out;
        }

    Default is 0;

Acknowledgements
    Thanks to Richard Soderberg for his performance improvements.

BUG REPORTS
    Please report bugs or other issues to <bug-params-check AT rt.org>.

AUTHOR
    This module by Jos Boumans <kane AT cpan.org>.

COPYRIGHT
    This library is free software; you may redistribute and/or modify it
    under the same terms as Perl itself.