Params::Check(3p) Perl Programmers Reference Guide Params::Check(3p) #
Params::Check(3p) Perl Programmers Reference Guide Params::Check(3p)
NNAAMMEE #
Params::Check - A generic input parsing/checking mechanism.
SSYYNNOOPPSSIISS #
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();
DDEESSCCRRIIPPTTIIOONN #
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:
TTeemmppllaattee 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, cchheecckk(()) 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.
FFuunnccttiioonnss cchheecckk(( \%%ttmmppll,, \%%aarrggss,, [[$$vveerrbboossee]] ));; This function is not exported by default, so you’ll have to ask for it via:
use Params::Check qw[check];
or use its fully qualified name instead.
"check" takes a list of arguments, as follows:
Template
This is a hash reference which contains a template as explained in
the "SYNOPSIS" and "Template" section.
Arguments
This is a reference to a hash of named arguments which need checking.
Verbose
A boolean to indicate whether "check" should be verbose and warn
about what went wrong in a check or not.
You can enable this program wide by setting the package variable
$Params::Check::VERBOSE to a true value. For details, see the section
on "Global Variables" below.
"check" will return when it fails, or a hashref with lowercase keys of
parsed arguments when it succeeds.
So a typical call to check would look like this:
my $parsed = check( \%template, \%arguments, $VERBOSE )
or warn q[Arguments could not be parsed!];
A lot of the behaviour of "check()" can be altered by setting package
variables. See the section on "Global Variables" for details on this.
aallllooww(( $$tteesstt__mmee,, \@@ccrriitteerriiaa ));; 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.
llaasstt__eerrrroorr(()) 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.
GGlloobbaall VVaarriiaabblleess The behaviour of Params::Check can be altered by changing the following global variables:
$$PPaarraammss::::CChheecckk::::VVEERRBBOOSSEE This controls whether Params::Check will issue warnings and explanations as to why certain things may have failed. If you set it to 0, Params::Check will not output any warnings.
The default is 1 when warnings are enabled, 0 otherwise;
$$PPaarraammss::::CChheecckk::::SSTTRRIICCTT__TTYYPPEE 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;
$$PPaarraammss::::CChheecckk::::AALLLLOOWW__UUNNKKNNOOWWNN If you set this flag, unknown options will still be present in the return value, rather than filtered out. This is useful if your subroutine is only interested in a few arguments, and wants to pass the rest on blindly to perhaps another subroutine.
The default is 0;
$$PPaarraammss::::CChheecckk::::SSTTRRIIPP__LLEEAADDIINNGG__DDAASSHHEESS If you set this flag, all keys passed in the following manner:
function( -key => 'val' );
will have their leading dashes stripped.
$$PPaarraammss::::CChheecckk::::NNOO__DDUUPPLLIICCAATTEESS If set to true, all keys in the template that are marked as to be stored in a scalar, will also be removed from the result set.
Default is false, meaning that when you use "store" as a template key,
"check" will put it both in the scalar you supplied, as well as in the
hashref it returns.
$$PPaarraammss::::CChheecckk::::PPRREESSEERRVVEE__CCAASSEE 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;
$$PPaarraammss::::CChheecckk::::OONNLLYY__AALLLLOOWW__DDEEFFIINNEEDD If set to true, Params::Check will require all values passed to be “defined”. If you wish to enable this on a ‘per key’ basis, use the template option “defined” instead.
Default is 0;
$$PPaarraammss::::CChheecckk::::SSAANNIITTYY__CCHHEECCKK__TTEEMMPPLLAATTEE 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;
$$PPaarraammss::::CChheecckk::::WWAARRNNIINNGGSS__FFAATTAALL If set to true, Params::Check will “croak” when an error during template validation occurs, rather than return “false”.
Default is 0;
$$PPaarraammss::::CChheecckk::::CCAALLLLEERR__DDEEPPTTHH 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;
AAcckknnoowwlleeddggeemmeennttss Thanks to Richard Soderberg for his performance improvements.
BBUUGG RREEPPOORRTTSS #
Please report bugs or other issues to <bug-params-check@rt.cpan.org>.
AAUUTTHHOORR #
This module by Jos Boumans <kane@cpan.org>.
CCOOPPYYRRIIGGHHTT #
This library is free software; you may redistribute and/or modify it
under the same terms as Perl itself.
perl v5.36.3 2014-11-17 Params::Check(3p)