NAME
JSON::DWIW - JSON converter that Does What I Want
SYNOPSIS
use JSON::DWIW;
my $json_obj = JSON::DWIW->new;
my $data = $json_obj->from_json($json_str);
my $str = $json_obj->to_json($data);
my ($data, $error_string) = $json_obj->from_json($json_str);
my $data = JSON::DWIW::deserialize($json_str);
my $error_str = JSON::DWIW::get_error_string();
use JSON::DWIW qw/deserialize_json from_json/
my $data = deserialize_json($json_str);
my $error_str = JSON::DWIW::get_error_string();
my $error_string = $json_obj->get_error_string;
my $error_data = $json_obj->get_error_data;
my $stats = $json_obj->get_stats;
my $data = $json_obj->from_json_file($file)
my $ok = $json_obj->to_json_file($data, $file);
my $data = JSON::DWIW->from_json($json_str);
my $str = JSON::DWIW->to_json($data);
my $data = JSON::DWIW->from_json($json_str, \%options);
my $str = JSON::DWIW->to_json($data, \%options);
my $true_value = JSON::DWIW->true;
my $false_value = JSON::DWIW->false;
my $data = { var1 => "stuff", var2 => $true_value,
var3 => $false_value, };
my $str = JSON::DWIW->to_json($data);
my $data = JSON::DWIW::deserialize($str, { start_depth => 1,
start_depth_handler => $handler });
DESCRIPTION
Other JSON modules require setting several parameters before calling the
conversion methods to do what I want. This module does things by default
that I think should be done when working with JSON in Perl. This module
also encodes and decodes faster than JSON.pm and JSON::Syck in my
benchmarks.
This means that any piece of data in Perl (assuming it's valid unicode)
will get converted to something in JSON instead of throwing an
exception. It also means that output will be strict JSON, while accepted
input will be flexible, without having to set any options.
For a list of changes in recent versions, see the documentation for
JSON::DWIW::Changes.
This module can be downloaded from
<http://www.cpan.org/authors/id/D/DO/DOWENS/>.
Encoding
Perl objects get encoded as their underlying data structure, with the
exception of Math::BigInt and Math::BigFloat, which will be output as
numbers, and JSON::DWIW::Boolean, which will get output as a true or
false value (see the true() and false() methods). For example, a blessed
hash ref will be represented as an object in JSON, a blessed array will
be represented as an array. etc. A reference to a scalar is dereferenced
and represented as the scalar itself. Globs, Code refs, etc., get
stringified, and undef becomes null.
Scalars that have been used as both a string and a number will be output
as a string. A reference to a reference is currently output as an empty
string, but this may change.
You may notice there is a deserialize function, but not a serialize one.
The deserialize function was written as a full rewrite (the parsing is
in a separate, event-based library now) of from_json (now from_json
calls deserialize). In the future, there will be a serialize function
that is a rewrite of to_json.
Decoding
Input is expected to utf-8. When decoding, null, true, and false become
undef, 1, and 0, repectively. Numbers that appear to be too long to be
supported natively are converted to Math::BigInt or Math::BigFloat
objects, if you have them installed. Otherwise, long numbers are turned
into strings to prevent data loss.
The parser is flexible in what it accepts and handles some things not in
the JSON spec:
quotes
Both single and double quotes are allowed for quoting a string,
e.g.,
[ "string1", 'string2' ]
bare keys
Object/hash keys can be bare if they look like an identifier, e.g.,
{ var1: "myval1", var2: "myval2" }
extra commas
Extra commas in objects/hashes and arrays are ignored, e.g.,
[1,2,3,,,4,]
becomes a 4 element array containing 1, 2, 3, and 4.
escape sequences
Latin1 hexadecimal escape sequences (\xHH) are accepted, as in
Javascript. Also, the vertical tab escape \v is recognized (\u000b).
comments
C, C++, and shell-style comments are accepted. That is
/* this is a comment */
// this is a comment
# this is also a comment
METHODS
"new(\%options)"
Create a new JSON::DWIW object.
%options is an optional hash of parameters that will change the bahavior
of this module when encoding to JSON. You may also pass these options as
the second argument to "to_json()" and "from_json()". The following
options are supported:
*bare_keys*
If set to a true value, keys in hashes will not be quoted when converted
to JSON if they look like identifiers. This is valid Javascript in
current browsers, but not in JSON.
*use_exceptions*
If set to a true value, errors found when converting to or from JSON
will result in "die()" being called with the error message. The default
is to not use exceptions.
*bad_char_policy*
This options indicates what should be done if bad characters are found,
e.g., bad utf-8 sequence. The default is to return an error and drop all
the output.
The following values for bad_char_policy are supported:
*error*
default action, i.e., drop any output built up and return an error
*convert*
Convert to a utf-8 char using the value of the byte as a code point.
This is basically the same as assuming the bad character is in latin-1
and converting it to utf-8.
*pass_through*
Ignore the error and pass through the raw bytes (invalid JSON)
*escape_multi_byte*
If set to a true value, escape all multi-byte characters (e.g., \u00e9)
when converting to JSON.
*ascii*
Synonym for escape_multi_byte
*pretty*
Add white space to the output when calling to_json() to make the output
easier for humans to read.
*convert_bool*
When converting from JSON, return objects for booleans so that "true"
and "false" can be maintained when encoding and decoding. If this flag
is set, then "true" becomes a JSON::DWIW::Boolean object that evaluates
to true in a boolean context, and "false" becomes an object that
evaluates to false in a boolean context. These objects are recognized by
the to_json() method, so they will be output as "true" or "false"
instead of "1" or "0".
*bare_solidus*
Don't escape solidus characters ("/") in strings. The output is still
legal JSON with this option turned on.
*minimal_escaping*
Only do required escaping in strings (solidus and quote). Tabs,
newlines, backspaces, etc., will not be escaped with this optioned
turned on (but the output will still be valid JSON).
*sort_keys*
Set to a true value to sort hash keys (alphabetically) when converting
to JSON.
*parse_number*
A subroutine reference to call when parsing a number. The subroutine
will be provided one string that is the number being parsed. The return
value from the subroutine will be used to populate the return data
instead of converting to a number.
E.g.,
my $json = '{ "a": 6.3e-10 }';
my $cb = sub { my ($val) = @_; return "I got the number '$val'"; };
my $data = JSON::DWIW::deserialize($json, { parse_number => $cb });
*parse_constant*
A subroutine reference to call when parsing a constant (true, false, or
null). The subroutine will be provided one string that is the constant
being parsed. The return value from the subroutine will be used to
populate the return data instead of converting to a boolean or undef.
See the "parse_number" option.
*start_depth*
Depth at which "start_depth_handler" should be called. See
"start_depth_handler".
*start_depth_handler*
A reference to a subroutine to called when parsing and at level
*start_depth* in the data structure. When specified along with
*start_depth*, the parser does not return the entire data structure.
Instead, it calls *start_depth_handler* for each element in the array
when the parser is at level *start_depth*. This is useful for parsing a
very large array without loading all the data into memory (especially
when using "deserialize_file").
E.g., with *start_depth* set to 1 and *start_depth_handler* set to
$handler:
my $str = '[ { "foo": "bar", "cat": 1 }, { "concat": 1, "lambda" : [ "one", 2, 3 ] } ]';
my $foo = { foo => [ ] };
my $handler = sub { push @{$foo->{foo}}, $_[0]; return 1; };
my $data = JSON::DWIW::deserialize($str, { start_depth => 1,
start_depth_handler => $handler });
print STDERR Data::Dumper->Dump([ $foo ], [ 'foo' ]) . "\n";
print STDERR Data::Dumper->Dump([ $data ], [ 'leftover_data' ]) . "\n";
# Output
$foo = {
'foo' => [
{
'cat' => 1,
'foo' => 'bar'
},
{
'lambda' => [
'one',
2,
3
],
'concat' => 1
}
]
};
$leftover_data = [];
"to_json"
Returns the JSON representation of $data (arbitrary datastructure). See
http://www.json.org/ for details.
Called in list context, this method returns a list whose first element
is the encoded JSON string and the second element is an error message,
if any. If $error_msg is defined, there was a problem converting to
JSON. You may also pass a second argument to to_json() that is a
reference to a hash of options -- see new().
my $json_str = JSON::DWIW->to_json($data);
my ($json_str, $error_msg) = JSON::DWIW->to_json($data);
my $json_str = JSON::DWIW->to_json($data, { use_exceptions => 1 });
Aliases: toJson, toJSON, objToJson
"deserialize($json_str, \%options)"
Returns the Perl data structure for the given JSON string. The value for
true becomes 1, false becomes 0, and null gets converted to undef.
This function should not be called as a method (for performance
reasons). Unlike "from_json()", it returns a single value, the data
structure resulting from the conversion. If the return value is undef,
check the result of the "get_error_string()" function/method to see if
an error is defined.
"deserialize_file($file, \%options)"
Same as deserialize, except that it takes a file as an argument. On
Unix, this mmap's the file, so it does not load a big file into memory
all at once, and does less buffer copying.
"from_json"
Similar to "deserialize()", but expects to be called as a method.
Called in list context, this method returns a list whose first element
is the data and the second element is the error message, if any. If
$error_msg is defined, there was a problem parsing the JSON string, and
$data will be undef. You may also pass a second argument to
"from_json()" that is a reference to a hash of options -- see "new()".
my $data = from_json($json_str)
my ($data, $error_msg) = from_json($json_str)
Aliases: fromJson, fromJSON, jsonToObj
"from_json_file"
Similar to "deserialize_file()", except that it expects to be called a a
method, and it also returns the error, if any, when called in list
context.
my ($data, $error_msg) = $json->from_json_file($file, \%options)
"to_json_file"
Converts $data to JSON and writes the result to the file $file.
Currently, this is simply a convenience routine that converts the data
to a JSON string and then writes it to the file.
my ($ok, $error) = $json->to_json_file($data, $file, \%options);
"get_error_string"
Returns the error message from the last call, if there was one, e.g.,
my $data = JSON::DWIW->from_json($json_str)
or die "JSON error: " . JSON::DWIW->get_error_string;
my $data = $json_obj->from_json($json_str)
or die "JSON error: " . $json_obj->get_error_string;
Aliases: get_err_str(), errstr()
"get_error_data"
Returns the error details from the last call, in a hash ref, e.g.,
$error_data = {
'byte' => 23,
'byte_col' => 23,
'col' => 22,
'char' => 22,
'version' => '0.15a',
'line' => 1
};
This is really only useful when decoding JSON.
Aliases: get_error(), error()
"get_stats"
Returns statistics from the last method called to encode or decode.
E.g., for an encoding ("to_json()" or "to_json_file()"),
$stats = {
'bytes' => 78,
'nulls' => 1,
'max_string_bytes' => 5,
'max_depth' => 2,
'arrays' => 1,
'numbers' => 6,
'lines' => 1,
'max_string_chars' => 5,
'strings' => 6,
'bools' => 1,
'chars' => 78,
'hashes' => 1
};
"true"
Returns an object that will get output as a true value when encoding to
JSON.
"false"
Returns an object that will get output as a false value when encoding to
JSON.
"json_to_xml($json, \%params)"
This function (not a method) converts the given JSON to XML. Hash/object
keys become tag names. Arrays that are hash values are output as
multiple tags with the hash key as the tag name.
Any characters in hash keys not in "[\w-]" (i.e., letters, numbers,
underscore, or dash), get converted to underscore ("_") when output as
XML tags.
Valid parameters in "\%params" are the same as for passing to
"deserialize()" or "from_json()", plus the "pretty" option, which will
add newlines and indentation to the XML to make it more human-readable.
Utilities
Following are some methods I use for debugging and testing.
"flagged_as_utf8($str)"
Returns true if the given string is flagged as utf-8.
"flag_as_utf8($str)"
Flags the given string as utf-8.
"unflag_as_utf8($str)"
Clears the flag that tells Perl the string is utf-8.
"is_valid_utf8($str)"
Returns true if the given string is valid utf-8 (regardless of the
flag).
"upgrade_to_utf8($str)"
Converts the string to utf-8, assuming it is latin1. This effects $str
itself in place, but also returns $str.
"code_point_to_utf8_str($cp)"
Returns a utf8 string containing the byte sequence for the given code
point.
"code_point_to_hex_bytes($cp)"
Returns a string representing the byte sequence for $cp encoding in
utf-8. E.g.,
my $hex_bytes = JSON::DWIW->code_point_to_hex_bytes(0xe9);
print "$hex_bytes\n"; # \xc3\xa9
"bytes_to_code_points($str)"
Returns a reference to an array of code points from the given string,
assuming the string is encoded in utf-8.
"peek_scalar($scalar)"
Dumps the internal structure of the given scalar.
BENCHMARKS
Need new benchmarks here.
DEPENDENCIES
Perl 5.6 or later
BUGS/LIMITATIONS
If you find a bug, please file a tracker request at
<http://rt.cpan.org/Public/Dist/Display.html?Name=JSON-DWIW>.
When decoding a JSON string, it is a assumed to be utf-8 encoded. The
module should detect whether the input is utf-8, utf-16, or utf-32.
AUTHOR
Don Owens <don@regexguy.com>
ACKNOWLEDGEMENTS
Thanks to Asher Blum for help with testing.
Thanks to Nigel Bowden for helping with compilation on Windows.
Thanks to Robert Peters for discovering and tracking down the source of
a number parsing bug.
Thanks to Mark Phillips for helping with a bug under Solaris on Sparc.
Thanks to Josh for helping debug [rt.cpan.org #47344].
LICENSE AND COPYRIGHT
Copyright (c) 2007-2010 Don Owens <don@regexguy.com>. All rights
reserved.
This is free software; you can redistribute it and/or modify it under
the same terms as Perl itself. See perlartistic.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
The JSON home page: <http://json.org/>
The JSON spec: <http://www.ietf.org/rfc/rfc4627.txt>
The JSON-RPC spec:
<http://json-rpc.org/wd/JSON-RPC-1-1-WD-20060807.html>
JSON
JSON::Syck (included in YAML::Syck)