# phpman > perldoc > Data::FormValidator::Filters ## NAME [Data::FormValidator::Filters](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters/markdown) - Basic set of filters available in an [Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown) profile. ## SYNOPSIS use [Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown); %profile = ( filters => 'trim', ... ); my $results = [Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown)->check( \%data, \%profile ); ## DESCRIPTION These are the builtin filters which may be specified as a name in the *filters*, *field_filters*, and *field_filter_regexp_map* parameters of the input profile. Filters are applied as the first step of validation, possibly modifying a copy of the validation before any constraints are checked. ## RECOMMENDED USE As a long time maintainer and user of [Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown), I recommend that filters be used with caution. They are immediately modifying the input provided, so the original data is lost. The few I recommend include "trim", which removes leading and trailing whitespace. I have this turned on by default by using [CGI::Application::Plugin::ValidateRM](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3AValidateRM/markdown). It's also generally safe to use the "lc" and "uc" filters if you need that kind of data transformation. Beyond simple filters, I recommend transforming the "valid" hash returned from validation if further changes are needed. ## PROCEDURAL INTERFACE You may also call these functions directly through the procedural interface by either importing them directly or importing the whole *:filters* group. For example, if you want to access the *trim* function directly, you could either do: use [Data::FormValidator::Filters](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters/markdown) (qw/filter_trim/); # or use [Data::FormValidator::Filters](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters/markdown) (qw/:filters/); $string = filter_trim($string); Notice that when you call filters directly, you'll need to prefix the filter name with "filter_". ## THE FILTERS FV_split use [Data::FormValidator::Filters](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters/markdown) qw(FV_split); # Validate every e-mail in a comma separated list field_filters => { several_emails => FV_split(qr/\s*,\s*/), # Any pattern that can be used by the 'split' builtin works. tab_sep_field => FV_split('\t'), }, constraint_methods => { several_emails => email(), }, With this filter, you can split a field into multiple values. The constraint for the field will then be applied to every value. This filter has a different naming convention because it is a higher-order function. Rather than returning a value directly, it returns a code reference to a standard [Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown) filter. After successfully being validated the values will appear as an arrayref. FV_replace use [Data::FormValidator::Filters](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters/markdown) qw(FV_replace); field_filters => { first_name => FV_replace(qr/Mark/,'Don'), }, FV_replace is a shorthand for writing simple find-and-replace filters. The above filter would be translated to this: sub { my $v = shift; $v =~ s/Mark/Don/; $v } For more complex filters, just write your own. trim Remove white space at the front and end of the fields. strip Runs of white space are replaced by a single space. digit Remove non digits characters from the input. alphanum Remove non alphanumeric characters from the input. integer Extract from its input a valid integer number. pos_integer Extract from its input a valid positive integer number. Bugs: This filter won't extract "9" from "a9+", it will instead extract "9+" neg_integer Extract from its input a valid negative integer number. Bugs: This filter will currently filter the case of "a9-" to become "9-", which it should leave it alone. decimal Extract from its input a valid decimal number. Bugs: Given "1,000.23", it will currently return "1.000.23" pos_decimal Extract from its input a valid positive decimal number. Bugs: Given "1,000.23", it will currently return "1.000.23" neg_decimal Extract from its input a valid negative decimal number. Bugs: Given "1,000.23", it will currently return "1.000.23" dollars Extract from its input a valid number to express dollars like currency. Bugs: This filter won't currently remove trailing numbers like "1.234". phone Filters out characters which aren't valid for an phone number. (Only accept digits [0-9], space, comma, minus, parenthesis, period and pound [#].) sql_wildcard Transforms shell glob wildcard (*) to the SQL like wildcard (%). quotemeta Calls the quotemeta (quote non alphanumeric character) builtin on its input. lc Calls the lc (convert to lowercase) builtin on its input. uc Calls the uc (convert to uppercase) builtin on its input. ucfirst Calls the ucfirst (Uppercase first letter) builtin on its input. ## SEE ALSO o L<[Data::FormValidator](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator/markdown)> o L<[Data::FormValidator::Constraints](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AConstraints/markdown)> o L<[Data::FormValidator::Filters::Image](https://www.chedong.com/phpMan.php/perldoc/Data%3A%3AFormValidator%3A%3AFilters%3A%3AImage/markdown)> - shrink incoming image uploads ## AUTHOR Author: Francis J. Lacoste <> Maintainer: Mark Stosberg <> ## COPYRIGHT Copyright (c) 1999,2000 iNsu Innovations Inc. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms as perl itself.