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JSON-Schema-Draft201909-0.005
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/ JSON::Schema::Draft201909

NAME

JSON::Schema::Draft201909 - Validate data against a schema

VERSION

version 0.005

SYNOPSIS

use JSON::Schema::Draft201909;

$js = JSON::Schema::Draft2019->new(
  output_format => 'flag',
  ... # other options
);
$result = $js->evaluate($instance_data, $schema_data);

DESCRIPTION

This module aims to be a fully-compliant JSON Schema evaluator and validator, targeting the currently-latest Draft 2019-09 version of the specification.

CONFIGURATION OPTIONS

output_format

One of: flag, basic, detailed, verbose. Defaults to basic. Passed to "output_format" in JSON::Schema::Draft201909::Result.

short_circuit

When true, evaluation will immediately return upon encountering the first validation failure, rather than continuing to find all errors.

Defaults to true when output_format is flag, and false otherwise.

max_traversal_depth

The maximum number of levels deep a schema traversal may go, before evaluation is halted. This is to protect against accidental infinite recursion, such as from two subschemas that each reference each other. Defaults to 50.

METHODS

evaluate_json_string

$result = $js->evaluate_json_string($data_as_json_string, $schema_data);

Evaluates the provided instance data against the known schema document.

The data is in the form of a JSON-encoded string (in accordance with RFC8259). The string is expected to be UTF-8 encoded.

The schema is in the form of a Perl data structure, representing a JSON Schema that respects the Draft 2019-09 meta-schema at https://json-schema.org/draft/2019-09/schema.

The result is a JSON::Schema::Draft201909::Result object, which can also be used as a boolean.

evaluate

$result = $js->evaluate($instance_data, $schema_data);

Evaluates the provided instance data against the known schema document.

The data is in the form of an unblessed nested Perl data structure representing any type that JSON allows (null, boolean, string, number, object, array).

The schema is in the form of a Perl data structure, representing a JSON Schema that respects the Draft 2019-09 meta-schema at https://json-schema.org/draft/2019-09/schema.

The result is a JSON::Schema::Draft201909::Result object, which can also be used as a boolean.

LIMITATIONS

TYPES

Perl is a more loosely-typed language than JSON. This module delves into a value's internal representation in an attempt to derive the true "intended" type of the value. However, if a value is used in another context (for example, a numeric value is concatenated into a string, or a numeric string is used in an arithmetic operation), additional flags can be added onto the variable causing it to resemble the other type. This should not be an issue if data validation is occurring immediately after decoding a JSON payload, or if the JSON string itself is passed to this module. If this turns out to be an issue in real environments, I may have to implement a lax_scalars option.

For more information, see "MAPPING" in Cpanel::JSON::XS.

SPECIFICATION COMPLIANCE

Until version 1.000 is released, this implementation is not fully specification-compliant.

The minimum extensible JSON Schema implementation requirements involve:

  • identifying, organizing, and linking schemas (with keywords such as $ref, $id, $schema, $anchor, $defs)

  • providing an interface to evaluate assertions

  • providing an interface to collect annotations

  • applying subschemas to instances and combining assertion results and annotation data accordingly.

  • support for all vocabularies required by the Draft 2019-09 metaschema, https://json-schema.org/draft/2019-09/schema

To date, missing components include most of these. More specifically, features to be added include:

SECURITY CONSIDERATIONS

The pattern and patternProperties keywords evaluate regular expressions from the schema. No effort is taken (at this time) to sanitize the regular expressions for embedded code or potentially pathological constructs that may pose a security risk, either via denial of service or by allowing exposure to the internals of your application. DO NOT RUN SCHEMAS FROM UNTRUSTED SOURCES.

SEE ALSO

SUPPORT

Bugs may be submitted through https://github.com/karenetheridge/JSON-Schema-Draft201909/issues.

I am also usually active on irc, as 'ether' at irc.perl.org and irc.freenode.org.

AUTHOR

Karen Etheridge <ether@cpan.org>

COPYRIGHT AND LICENCE

This software is copyright (c) 2020 by Karen Etheridge.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.