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This chapter covers how to encode and decode JSON objects using Perl programming language. Let”s start with preparing the environment to start our programming with Perl for JSON.
Environment
Before you start encoding and decoding JSON using Perl, you need to install JSON module, which can be obtained from CPAN. Once you downloaded JSON-2.53.tar.gz or any other latest version, follow the steps mentioned below −
$tar xvfz JSON-2.53.tar.gz $cd JSON-2.53 $perl Makefile.PL $make $make install
JSON Functions
Function | Libraries |
---|---|
encode_json | Converts the given Perl data structure to a UTF-8 encoded, binary string. |
decode_json | Decodes a JSON string. |
to_json | Converts the given Perl data structure to a json string. |
from_json | Expects a json string and tries to parse it, returning the resulting reference. |
convert_blessed | Use this function with true value so that Perl can use TO_JSON method on the object”s class to convert an object into JSON. |
Encoding JSON in Perl (encode_json)
Perl encode_json() function converts the given Perl data structure to a UTF-8 encoded, binary string.
Syntax
$json_text = encode_json ($perl_scalar ); or $json_text = JSON->new->utf8->encode($perl_scalar);
Example
The following example shows arrays under JSON with Perl −
#!/usr/bin/perl use JSON; my %rec_hash = (''a'' => 1, ''b'' => 2, ''c'' => 3, ''d'' => 4, ''e'' => 5); my $json = encode_json %rec_hash; print "$jsonn";
While executing, this will produce the following result −
{"e":5,"c":3,"a":1,"b":2,"d":4}
The following example shows how Perl objects can be converted into JSON −
#!/usr/bin/perl package Emp; sub new { my $class = shift; my $self = { name => shift, hobbies => shift, birthdate => shift, }; bless $self, $class; return $self; } sub TO_JSON { return { %{ shift() } }; } package main; use JSON; my $JSON = JSON->new->utf8; $JSON->convert_blessed(1); $e = new Emp( "sachin", "sports", "8/5/1974 12:20:03 pm"); $json = $JSON->encode($e); print "$jsonn";
On executing, it will produce the following result −
{"birthdate":"8/5/1974 12:20:03 pm","name":"sachin","hobbies":"sports"}
Decoding JSON in Perl (decode_json)
Perl decode_json() function is used for decoding JSON in Perl. This function returns the value decoded from json to an appropriate Perl type.
Syntax
$perl_scalar = decode_json $json_text or $perl_scalar = JSON->new->utf8->decode($json_text)
Example
The following example shows how Perl can be used to decode JSON objects. Here you will need to install Data::Dumper module if you already do not have it on your machine.
#!/usr/bin/perl use JSON; use Data::Dumper; $json = ''{"a":1,"b":2,"c":3,"d":4,"e":5}''; $text = decode_json($json); print Dumper($text);
On executing, it will produce following result −
$VAR1 = { ''e'' => 5, ''c'' => 3, ''a'' => 1, ''b'' => 2, ''d'' => 4 };
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