JSON::Validator(3) Validate data against a JSON schema




use JSON::Validator;
my $validator = JSON::Validator->new;
# Define a schema - http://json-schema.org/examples.html
# You can also load schema from disk or web
type => "object",
required => ["firstName", "lastName"],
properties => {
firstName => {type => "string"},
lastName => {type => "string"},
age => {type => "integer", minimum => 0, description => "Age in years"}
# Validate your data
@errors = $validator->validate({firstName => "Jan Henning", lastName => "Thorsen", age => -42});
# Do something if any errors was found
die "@errors" if @errors;


JSON::Validator is a class for validating data against JSON schemas. You might want to use this instead of JSON::Schema if you need to validate data against draft 4 <https://github.com/json-schema/json-schema/tree/master/draft-04> of the specification.

Supported schema formats

JSON::Validator can load JSON schemas in multiple formats: Plain perl data structured (as shown in ``SYNOPSIS'') or files on disk/web in the JSON/YAML format. The JSON parsing is done using Mojo::JSON, while the YAML parsing is done with an optional modules which need to be installed manually. JSON::Validator will look for the YAML modules in this order: YAML::XS, YAML::Syck. The order is set by which module that performs the best, so it might change in the future.


Here are some resources that are related to JSON schemas and validation:



The method ``validate'' and the function ``validate_json'' returns error objects when the input data violates the ``schema''. Each of the objects looks like this:

  bless {
    message => "Some description",
    path => "/json/path/to/node",
  }, "JSON::Validator::Error"

See also JSON::Validator::Error.


The error object overloads the following operators:
  • bool

    Returns a true value.

  • string

    Returns the ``path'' and ``message'' part as a string: ``$path: $message''.

Special cases

Have a look at the test suite <https://github.com/jhthorsen/json-validator/tree/master/t> for documented examples of the error cases. Especially look at "jv-allof.t", "jv-anyof.t" and "jv-oneof.t".

The special cases for ``allOf'', ``anyOf'' and ``oneOf'' will contain the error messages from all the failing rules below. It can be a bit hard to read, so if the error message is long, then you might want to run a smaller test with "JSON_VALIDATOR_DEBUG=1".

Example error object:

  bless {
    message => "(String is too long: 8/5. String is too short: 8/12)",
    path => "/json/path/to/node",
  }, "JSON::Validator::Error"

Note that these error messages are subject for change. Any suggestions are most welcome!



  use JSON::Validator "validate_json";
  @errors = validate_json $data, $schema;

This can be useful in web applications:

  @errors = validate_json $c->req->json, "data://main/spec.json";

See also ``validate'' and ``ERROR OBJECT'' for more details.



  $self = $self->cache_dir($path);
  $path = $self->cache_dir;

Path to where downloaded spec files should be cached. Defaults to "JSON_VALIDATOR_CACHE_DIR" or the bundled spec files that are shipped with this distribution.


  $hash_ref = $self->formats;
  $self = $self->formats(\%hash);

Holds a hash-ref, where the keys are supported JSON type ``formats'', and the values holds a code block which can validate a given format.

Note! The modules mentioned below are optional.

  • date-time

    An RFC3339 timestamp in UTC time. This is formatted as ``YYYY-MM-DDThh:mm:ss.fffZ''. The milliseconds portion (``.fff'') is optional

  • email

    Validated against the RFC5322 spec.

  • hostname

    Will be validated using Data::Validate::Domain if installed.

  • ipv4

    Will be validated using Data::Validate::IP if installed or fall back to a plain IPv4 IP regex.

  • ipv6

    Will be validated using Data::Validate::IP if installed.

  • regex

    EXPERIMENTAL. Will check if the string is a regex, using "qr{...}".

  • uri

    Validated against the RFC3986 spec.


  $ua = $self->ua;
  $self = $self->ua(Mojo::UserAgent->new);

Holds a Mojo::UserAgent object, used by ``schema'' to load a JSON schema from remote location.

Note that the default Mojo::UserAgent will detect proxy settings and have ``max_redirects'' in Mojo::UserAgent set to 3. (These settings are EXPERIMENTAL and might change without a warning)



  $self = $self->coerce(booleans => 1, numbers => 1, strings => 1);
  $self = $self->coerce({booleans => 1, numbers => 1, strings => 1});
  $self = $self->coerce(1) # enable all
  $hash = $self->coerce;

Set the given type to coerce. Before enabling coercion this module is very strict when it comes to validating types. Example: The string "1" is not the same as the number 1, unless you have coercion enabled.

WARNING! Enabling coercion might hide bugs in your api, which would have been detected if you were strict. For example JavaScript is very picky on a number being an actual number. This module tries it best to convert the data on the fly into the proper value, but this means that you unit tests might be ok, but the client side libraries (that care about types) might break.

Loading a YAML document will enable ``booleans'' automatically. This feature is experimental, but was added since YAML has no real concept of booleans, such as Mojo::JSON or other JSON parsers.

The coercion rules are EXPERIMENTAL and will be tighten/loosen if bugs are reported. See <https://github.com/jhthorsen/json-validator/issues/8> for more details.


  $self = $self->schema(\%schema);
  $self = $self->schema($url);
  $schema = $self->schema;

Used to set a schema from either a data structure or a URL.

$schema will be a Mojo::JSON::Pointer object when loaded, and "undef" by default.

The $url can take many forms, but needs to point to a text file in the JSON or YAML format.

  • http://... or https://...

    A web resource will be fetched using the Mojo::UserAgent, stored in ``ua''.

  • data://Some::Module/file.name

    This version will use ``data_section'' in Mojo::Loader to load ``file.name'' from the module ``Some::Module''.

  • /path/to/file

    An URL (without a recognized scheme) will be loaded from disk.


  $self = $class->singleton;

Returns the JSON::Validator object used by ``validate_json''.


  @errors = $self->validate($data);

Validates $data against a given JSON ``schema''. @errors will contain validation error objects or be an empty list on success.

See ``ERROR OBJECT'' for details.


Copyright (C) 2014-2015, Jan Henning Thorsen

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.


Jan Henning Thorsen - "[email protected]"