A data domain is a description of a set of values, either scalar or structured
(arrays or hashes). The description can include many constraints, like minimal
or maximal values, regular expressions, required fields, forbidden fields, and
also contextual dependencies. From that description, one can then invoke the
domain's inspect method to check if a given value belongs to it or not. In case
of mismatch, a structured set of error messages is returned.

The motivation for writing this package was to be able to express in a compact
way some possibly complex constraints about structured data. Typically the data
is a Perl tree (nested hashrefs or arrayrefs) that may come from XML, JSON, from
a database through DBIx::DataModel, or from postprocessing an HTML form through
CGI::Expand. Data::Domain is a kind of tree parser on that structure, with some
facilities for dealing with dependencies within the structure, and with several
options to finely tune the error messages returned to the user.

WWW: https://metacpan.org/release/Data-Domain