phpMan > man > Cpanel::JSON::XS::Type(3pm)

NAME
    Cpanel::JSON::XS::Type - Type support for JSON encode

SYNOPSIS
     use Cpanel::JSON::XS;
     use Cpanel::JSON::XS::Type;


     encode_json([10, "10", 10.25], [JSON_TYPE_INT, JSON_TYPE_INT, JSON_TYPE_STRING]);
     # '[10,10,"10.25"]'

     encode_json([10, "10", 10.25], json_type_arrayof(JSON_TYPE_INT));
     # '[10,10,10]'

     encode_json(1, JSON_TYPE_BOOL);
     # 'true'

     my $perl_struct = { key1 => 1, key2 => "2", key3 => 1 };
     my $type_spec = { key1 => JSON_TYPE_STRING, key2 => JSON_TYPE_INT, key3 => JSON_TYPE_BOOL };
     my $json_string = encode_json($perl_struct, $type_spec);
     # '{"key1":"1","key2":2,"key3":true}'

     my $perl_struct = { key1 => "value1", key2 => "value2", key3 => 0, key4 => 1, key5 => "string", key6 => "string2" };
     my $type_spec = json_type_hashof(JSON_TYPE_STRING);
     my $json_string = encode_json($perl_struct, $type_spec);
     # '{"key1":"value1","key2":"value2","key3":"0","key4":"1","key5":"string","key6":"string2"}'

     my $perl_struct = { key1 => { key2 => [ 10, "10", 10.6 ] }, key3 => "10.5" };
     my $type_spec = { key1 => json_type_anyof(JSON_TYPE_FLOAT, json_type_hashof(json_type_arrayof(JSON_TYPE_INT))), key3 => JSON_TYPE_FLOAT };
     my $json_string = encode_json($perl_struct, $type_spec);
     # '{"key1":{"key2":[10,10,10]},"key3":10.5}'


     my $value = decode_json('false', 1, my $type);
     # $value is 0 and $type is JSON_TYPE_BOOL

     my $value = decode_json('0', 1, my $type);
     # $value is 0 and $type is JSON_TYPE_INT

     my $value = decode_json('"0"', 1, my $type);
     # $value is 0 and $type is JSON_TYPE_STRING

     my $json_string = '{"key1":{"key2":[10,"10",10.6]},"key3":"10.5"}';
     my $perl_struct = decode_json($json_string, 0, my $type_spec);
     # $perl_struct is { key1 => { key2 => [ 10, 10, 10.6 ] }, key3 => 10.5 }
     # $type_spec is { key1 => { key2 => [ JSON_TYPE_INT, JSON_TYPE_STRING, JSON_TYPE_FLOAT ] }, key3 => JSON_TYPE_STRING }

DESCRIPTION
    This module provides stable JSON type support for the Cpanel::JSON::XS encoder which doesn't
    depend on any internal perl scalar flags or characteristics. Also it provides real JSON types
    for Cpanel::JSON::XS decoder.

    In most cases perl structures passed to encode_json come from other functions or from other
    modules and caller of Cpanel::JSON::XS module does not have control of internals or they are
    subject of change. So it is not easy to support enforcing types as described in the simple
    scalars section.

    For services based on JSON contents it is sometimes needed to correctly process and enforce JSON
    types.

    The function decode_json takes optional third scalar parameter and fills it with specification
    of json types.

    The function encode_json takes a perl structure as its input and optionally also a json type
    specification in the second parameter.

    If the specification is not provided (or is undef) internal perl scalar flags are used for the
    resulting JSON type. The internal flags can be changed by perl itself, but also by external
    modules. Which means that types in resulting JSON string aren't stable. Specially it does not
    work reliable for dual vars and scalars which were used in both numeric and string operations.
    See simple scalars.

    To enforce that specification is always provided use "require_types". In this case when "encode"
    is called without second argument (or is undef) then it croaks. It applies recursively for all
    sub-structures.

  JSON type specification for scalars:
    JSON_TYPE_BOOL
        It enforces JSON boolean in resulting JSON, i.e. either "true" or "false". For determining
        whether the scalar passed to the encoder is true, standard perl boolean logic is used.

    JSON_TYPE_INT
        It enforces JSON number without fraction part in the resulting JSON. Equivalent of perl
        function int is used for conversion.

    JSON_TYPE_FLOAT
        It enforces JSON number with fraction part in the resulting JSON. Equivalent of perl
        operation +0 is used for conversion.

    JSON_TYPE_STRING
        It enforces JSON string type in the resulting JSON.

    JSON_TYPE_NULL
        It represents JSON "null" value. Makes sense only when passing perl's "undef" value.

    For each type, there also exists a type with the suffix "_OR_NULL" which encodes perl's "undef"
    into JSON "null". Without type with suffix "_OR_NULL" perl's "undef" is converted to specific
    type according to above rules.

  JSON type specification for arrays:
    [...]
        The array must contain the same number of elements as in the perl array passed for encoding.
        Each element of the array describes the JSON type which is enforced for the corresponding
        element of the perl array.

    json_type_arrayof
        This function takes a JSON type specification as its argument which is enforced for every
        element of the passed perl array.

  JSON type specification for hashes:
    {...}
        Each hash value for corresponding key describes the JSON type specification for values of
        passed perl hash structure. Keys in hash which are not present in passed perl hash structure
        are simple ignored and not used.

    json_type_hashof
        This function takes a JSON type specification as its argument which is enforced for every
        value of passed perl hash structure.

  JSON type specification for alternatives:
    json_type_anyof
        This function takes a list of JSON type alternative specifications (maximally one scalar,
        one array, and one hash) as its input and the JSON encoder chooses one that matches.

    json_type_null_or_anyof
        Like "json_type_anyof", but scalar can be only perl's "undef".

  Recursive specifications
    json_type_weaken
        This function can be used as an argument for "json_type_arrayof", "json_type_hashof" or
        "json_type_anyof" functions to create weak references suitable for complicated recursive
        structures. It depends on the weaken function from Scalar::Util module. See following
        example:

          my $struct = {
              type => JSON_TYPE_STRING,
              array => json_type_arrayof(JSON_TYPE_INT),
          };
          $struct->{recursive} = json_type_anyof(
              json_type_weaken($struct),
              json_type_arrayof(JSON_TYPE_STRING),
          );

        If you want to encode all perl scalars to JSON string types despite how complicated is input
        perl structure you can define JSON type specification for alternatives recursively. It could
        be defined as:

          my $type = json_type_anyof();
          $type->[0] = JSON_TYPE_STRING_OR_NULL;
          $type->[1] = json_type_arrayof(json_type_weaken($type));
          $type->[2] = json_type_hashof(json_type_weaken($type));

          print encode_json([ 10, "10", { key => 10 } ], $type);
          # ["10","10",{"key":"10"}]

        An alternative solution for encoding all scalars to JSON strings is to use "type_all_string"
        method of Cpanel::JSON::XS itself:

          my $json = Cpanel::JSON::XS->new->type_all_string;
          print $json->encode([ 10, "10", { key => 10 } ]);
          # ["10","10",{"key":"10"}]

AUTHOR
    Pali <pali AT cpan.org>

COPYRIGHT & LICENSE
    Copyright (c) 2017, GoodData Corporation. All rights reserved.

    This module is available under the same licences as perl, the Artistic license and the GPL.