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Steven Haryanto

NAME

Data::Sah - Fast and featureful data structure validation

VERSION

This document describes version 0.29 of Data::Sah (from Perl distribution Data-Sah), released on 2014-06-30.

SYNOPSIS

Non-OO interface:

 use Data::Sah qw(
     normalize_schema
     gen_validator
 );

 # generate a validator for schema
 my $v = gen_validator(["int*", min=>1, max=>10]);

 # validate your data using the generated validator
 say "valid" if $v->(5);     # valid
 say "valid" if $v->(11);    # invalid
 say "valid" if $v->(undef); # invalid
 say "valid" if $v->("x");   # invalid

 # generate validator which reports error message string, in Indonesian
 my $v = gen_validator(["int*", min=>1, max=>10],
                       {return_type=>'str', lang=>'id_ID'});
 say $v->(5);  # ''
 say $v->(12); # 'Data tidak boleh lebih besar dari 10'
               # (in English: 'Data must not be larger than 10')

 # normalize a schema
 my $nschema = normalize_schema("int*"); # => ["int", {req=>1}, {}]

OO interface (more advanced usage):

 use Data::Sah;
 my $sah = Data::Sah->new;

 # get perl compiler
 my $pl = $sah->get_compiler("perl");

 # compile schema into Perl code
 my $cd = $pl->compile(schema => $schema, ...);

DESCRIPTION

This module, Data::Sah, implements compilers for producing Perl and JavaScript validators, as well as translatable human description text from Sah schemas. Compiler approach is used instead of interpreter for faster speed.

The generated validator code can run without this module.

STATUS

Some features are not implemented yet:

  • General

    • def/subschema

    • expression

    • buf type

    • date/datetime type

    • obj: meths, attrs properties

    • .prio, .err_msg, .ok_err_msg attributes

    • .result_var attribute

    • BaseType: if, prefilters, postfilters, check, prop, check_prop clauses

    • HasElems: each_elem, each_index, check_each_elem, check_each_index, exists clauses

    • HasElems: len, elems, indices properties

    • hash: check_each_key, check_each_value, allowed_keys_re, forbidden_keys_re clauses

    • array: uniq clauses

  • human compiler

    • markdown output

  • perl compiler

  • js compiler

EXPORTS

None exported by default.

normalize_schema($schema) => ARRAY

Normalize $schema.

Can also be used as a method.

gen_validator($schema, \%opts) => CODE (or STR)

Generate validator code for $schema. Can also be used as a method. Known options (unknown options will be passed to Perl schema compiler):

  • accept_ref => BOOL (default: 0)

    Normally the generated validator accepts data, as in:

     $res = $vdr->($data);
     $res = $vdr->(42);

    If this option is set to true, validator accepts reference to data instead, as in:

     $res = $vdr->(\$data);

    This allows $data to be modified by the validator (mainly, to set default value specified in schema). For example:

     my $data;
     my $vdr = gen_validator([int => {min=>0, max=>10, default=>5}],
                             {accept_ref=>1});
     my $res = $vdr->(\$data);
     say $res;  # => 1 (success)
     say $data; # => 5
  • source => BOOL (default: 0)

    If set to 1, return source code string instead of compiled subroutine. Usually only needed for debugging (but see also $Log_Validator_Code and LOG_SAH_VALIDATOR_CODE if you want to log validator source code).

ATTRIBUTES

compilers => HASH

A mapping of compiler name and compiler (Data::Sah::Compiler::*) objects.

VARIABLES

$Log_Validator_Code (bool, default: 0)

ENVIRONMENT

LOG_SAH_VALIDATOR_CODE

METHODS

new() => OBJ

Create a new Data::Sah instance.

$sah->get_compiler($name) => OBJ

Get compiler object. Data::Sah::Compiler::$name will be loaded first and instantiated if not already so. After that, the compiler object is cached.

Example:

 my $plc = $sah->get_compiler("perl"); # loads Data::Sah::Compiler::perl

$sah->normalize_schema($schema) => HASH

Normalize a schema, e.g. change int* into [int => {req=>1}], as well as do some sanity checks on it. Returns the normalized schema if succeeds, or dies on error.

Can also be used as a function.

$sah->normalize_clset($clset[, \%opts]) => HASH

Normalize a clause set, e.g. change {"!match"=>"abc"} into {"match"=>"abc", "match.op"=>"not"}. Produce a shallow copy of the input clause set hash.

Can also be used as a function.

$sah->normalize_var($var) => STR

Normalize a variable name in expression into its fully qualified/absolute form.

Not yet implemented (pending specification).

For example:

 [int => {min => 10, 'max=' => '2*$min'}]

$min in the above expression will be normalized as schema:clauses.min.

$sah->gen_validator($schema, \%opts) => CODE

Use the Perl compiler to generate validator code. Can also be used as a function. See the documentation as a function for list of known options.

MODULE ORGANIZATION

Data::Sah::Type::* roles specify Sah types, e.g. Data::Sah::Type::bool specifies the bool type. It can also be used to name distributions that introduce new types, e.g. Data-Sah-Type-complex which introduces complex number type.

Data::Sah::FuncSet::* roles specify bundles of functions, e.g. <Data::Sah::FuncSet::Core> specifies the core/standard functions.

Data::Sah::Compiler::$LANG:: namespace is for compilers. Each compiler might further contain <::TH::*> and <::FSH::*> subnamespaces to implement appropriate functionalities, e.g. Data::Sah::Compiler::perl::TH::bool is the bool type handler for the Perl compiler and Data::Sah::Compiler::perl::FSH::Core is the Core funcset handler for Perl compiler.

Data::Sah::TypeX::$TYPENAME::$CLAUSENAME namespace can be used to name distributions that extend an existing Sah type by introducing a new clause for it. See Data::Sah::Manual::Extending for an example.

Data::Sah::Lang::$LANGCODE namespaces are for modules that contain translations. They are further organized according to the organization of other Data::Sah modules, e.g. Data::Sah::Lang::en_US::Type::int or Data::Sah::Lang::en_US::TypeX::str::is_palindrome.

Sah::Schema:: namespace is reserved for modules that contain bundles of schemas. For example, Sah::Schema::CPANMeta contains the schema to validate CPAN META.yml. Sah::Schema::Int contains various schemas for integers such as pos_int, int8, uint32. Sah::Schema::Sah contains the schema for Sah schema itself.

FAQ

See also Sah::FAQ.

Relation to Data::Schema?

Data::Schema is the old incarnation of this module, deprecated since 2011.

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.

Comparison to {JSON::Schema, Data::Rx, Data::FormValidator, ...}?

See Sah::FAQ.

Why is it so slow?

You probably do not reuse the compiled schema, e.g. you continually destroy and recreate Data::Sah object, or repeatedly recompile the same schema. To gain the benefit of compilation, you need to keep the compiled result and use the generated Perl code repeatedly.

Can I generate another schema dynamically from within the schema?

For example:

 // if first element is an integer, require the array to contain only integers,
 // otherwise require the array to contain only strings.
 ["array", {"min_len": 1, "of=": "[is_int($_[0]) ? 'int':'str']"}]

Currently no, Data::Sah does not support expression on clauses that contain other schemas. In other words, dynamically generated schemas are not supported. To support this, if the generated code needs to run independent of Data::Sah, it needs to contain the compiler code itself (or an interpreter) to compile or evaluate the generated schema.

However, an eval_schema() Sah function which uses Data::Sah can be trivially declared and target the Perl compiler.

How to display the validator code being generated?

If you use the OO interface, e.g.:

 # generate perl code
 my $cd = $plc->compile(schema=>..., ...);

then the generated code is in $cd->{result} and you can just print it.

If you generate validator using gen_validator(), you can set environment LOG_SAH_VALIDATOR_CODE or package variable $Log_Validator_Code to true and the generated code will be logged at trace level using Log::Any. The log can be displayed using, e.g., Log::Any::App:

 % LOG_SAH_VALIDATOR_CODE=1 TRACE=1 \
   perl -MLog::Any::App -MData::Sah=gen_validator \
   -e '$sub = gen_validator([int => min=>1, max=>10])'

Sample output:

 normalized schema=['int',{max => 10,min => 1},{}]
 schema already normalized, skipped normalization
 validator code:
    1|do {
    2|    require Scalar::Util::Numeric;
    3|    sub {
    4|        my ($data) = @_;
    5|        my $_sahv_res =
     |
    7|            # skip if undef
    8|            (!defined($data) ? 1 :
     |
   10|            (# check type 'int'
   11|            (Scalar::Util::Numeric::isint($data))
     |
   13|            &&
     |
   15|            (# clause: min
   16|            ($data >= 1))
     |
   18|            &&
     |
   20|            (# clause: max
   21|            ($data <= 10))));
     |
   23|        return($_sahv_res);
   24|    }}

How to show the validation error message? The validator only returns true/false!

Pass the <return_type="str">> to get an error message string on error, or <return_type="full">> to get a hash of detailed error messages. Note also that the error messages are translateable (e.g. use LANG or lang=>... option. For example:

 my $v = gen_validator([int => between => [1,10]], {return_type=>"str"});
 say "$_: ", $v->($_) for 1, "x", 12;

will output:

 1:
 "x": Input is not of type integer
 12: Must be between 1 and 10

What does the @... prefix that is sometimes shown on the error message mean?

It shows the path to data item that fails the validation, e.g.:

 my $v = gen_validator([array => of => [int=>min=>5], {return_type=>"str"});
 say $v->([10, 5, "x"]);

prints:

 @2: Input is not of type integer

which means that the third element (subscript 2) of the array fails the validation. Another example:

 my $v = gen_validator([array => of => [hash=>keys=>{a=>"int"}]]);
 say $v->([{}, {a=>1.1}]);

prints:

 @1/a: Input is not of type integer

How to show the process of validation by the compiled code?

If you are generating Perl code from schema, you can pass debug=>1 option so the code contains logging (Log::Any-based) and other debugging information, which you can display. For example:

 % TRACE=1 perl -MLog::Any::App -MData::Sah=gen_validator -E'
   $v = gen_validator([array => of => [hash => {req_keys=>["a"]}]],
                      {return_type=>"str", debug=>1});
   say "Validation result: ", $v->([{a=>1}, "x"]);'

will output:

 ...
 [spath=[]]skip if undef ...
 [spath=[]]check type 'array' ...
 [spath=['of']]clause: {"of":["hash",{"req_keys":["a"]}]} ...
 [spath=['of']]skip if undef ...
 [spath=['of']]check type 'hash' ...
 [spath=['of','req_keys']]clause: {"req_keys":["a"]} ...
 [spath=['of']]skip if undef ...
 [spath=['of']]check type 'hash' ...
 Validation result: [spath=of]@1: Input is not of type hash

What else can I do with the compiled code?

Data::Sah offers some options in code generation. Beside compiling the validator code into a subroutine, there are also some other options. Examples:

  • Dist::Zilla::Plugin::Rinci::Validate

    This plugin inserts the generated code (without the sub { ... } wrapper) to validate the content of %args right before # VALIDATE_ARG or # VALIDATE_ARGS like below:

     $SPEC{foo} = {
         args => {
             arg1 => { schema => ..., req=>1 },
             arg2 => { schema => ... },
         },
         ...
     };
     sub foo {
         my %args = @_; # VALIDATE_ARGS
     }

    The schemas will be retrieved from the Rinci metadata ($SPEC{foo} above). This means, subroutines in your built distribution will do argument validation.

  • Perinci::Sub::Wrapper

    This module is part of the Perinci family. What the module does is basically wrap your subroutine with a wrapper code that can include validation code (among others). This is a convenient way to add argument validation to an existing subroutine/code.

TODO

  • (perl compiler) Replace smartmatch because of its inconsistent behavior

    <$data ~~ ["x", 1]> will do string comparison, while <$data ~~ [1, "x"]> or even <$data ~~ ["1", "x"]> will do a numeric comparison.

SEE ALSO

Other compiled validators

Other interpreted validators

Params::Validate is very fast, although minimal. Data::Rx, Kwalify, Data::Verifier, Data::Validator, JSON::Schema, Validation::Class.

For Moo/Mouse/Moose stuffs: Moose type system, MooseX::Params::Validate, Type::Tiny, among others.

Form-oriented: Data::FormValidator, FormValidator::Lite, among others.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Data-Sah.

SOURCE

Source repository is at https://github.com/sharyanto/perl-Data-Sah.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Data-Sah

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2014 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.




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