Sah::FAQ - Frequently asked questions
version 0.9.2
I'll leave it to others to debate DSL (like templating language, schema, etc) vs pure Perl. But my principle is: if a DSL can save me significant amount of time, keep my code clean and maintainable, even if it's not perfect (what is?), I'll take it. 90% of the time, my schemas are some variations of the simple cases like:
'str*' [str => {len_between=>[1, 10], match=>'some regex'}] [str => {in => [qw/a b c and some other values/]}] [array => {of => 'some_other_type'}] [hash => {keys => {key1=>'some schema', ...}, req_keys => [qw/.../], ...}]
and writing schemas is faster and less tedious/error-prone than writing equivalent Perl code, plus Sah can generate JavaScript code and human description text for me. For more complex validation I stay with Sah until it starts to get unwieldy. It usually can go pretty far since I can add functions and custom clauses to its types; it's for the rare and very complex validation needs that I go pure Perl. Your mileage may vary.
Sah is an Indonesian word, meaning 'valid' or 'legal'. It's picked because it's short.
The previous incarnation of this module uses the namespace Data::Schema, started in 2009 and deprecated in 2011 in favor of Sah.
There are enough incompatibilities between the two (some different syntaxes, renamed clauses). Also, some terminology have been changed, e.g. "attribute" become "clauses", "suffix" becomes "attributes". This warrants a new name.
Compared to Data::Schema, Sah always compiles schemas and there is much greater flexibility in code generation (can generate data term, can generate code to validate multiple schemas, etc). There is no longer hash form, schema is either a string or an array. Some clauses have been renamed (mostly, commonly used clauses are abbreviated, Huffman encoding thingy), some removed (usually because they are replaced by a more general solution), and new ones have been added.
If you use Data::Schema, I recommend you migrate to Data::Sah as I will not be developing Data::Schema anymore. Sorry, there's currently no tool to convert your Data::Schema schemas to Sah, but it should be relatively straightforward. I recommend that you look into Data::Sah::Easy.
not
not_in
There are generally no not_CLAUSE clauses. Instead, a generic !CLAUSE syntax is provided. Examples:
not_CLAUSE
!CLAUSE
# an integer that is not 0 [int => {'!is' => 0}]
in
!in
You can't do this since it will cause a conflict:
[str => {in => [qw/a b c/], '!in' => [qw/x y z/]}]
However, you can do this:
[str => {'cset&' => [{in => [qw/a b c/]}, {'!in' => [qw/x y z/]}]}]
You can use if clause and negate the clauses. For example:
if
if => ['!div_by' => 2, '!div_by' => 5]
XXX (Turn off hash merging using the '' Data::ModeMerge options key.
''
Steven Haryanto <stevenharyanto@gmail.com>
This software is copyright (c) 2012 by Steven Haryanto.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Sah, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Sah
CPAN shell
perl -MCPAN -e shell install Sah
For more information on module installation, please visit the detailed CPAN module installation guide.