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JSON::Path - search nested hashref/arrayref structures using JSONPath
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Bugs
Please report any bugs to <http://rt.cpan.org/>.
Contributors
Toby Inkster https://github.com/tobyink
Szymon Nieznański https://github.com/s-nez
Heiko Jansen https://github.com/heikojansen
Mitsuhiro Nakamura https://github.com/mnacamura
David Escribano García https://github.com/DavidEGx
Thomas Helsel https://github.com/thelsel
Patrick Cronin https://github.com/PatrickCronin
James Bowery https://github.com/jabowery
Slaven Rezić https://github.com/eserte
Max Laager https://github.com/mlaagerc2c
Elvin Aslanov https://github.com/rwp0
James Raspass https://github.com/JRaspass
Bernhard Schmalhofer https://github.com/bschmalhofer
Copyright And Licence
Copyright 2007 Stefan Goessner.
Copyright 2010-2013 Toby Inkster.
Copyright 2021-2024 Aurelia Peters
This module is tri-licensed. It is available under the X11 (a.k.a. MIT) licence; you can also
redistribute it and/or modify it under the same terms as Perl itself.
a.k.a."TheMITLicence"
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the
following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial
portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
THE USE OR OTHER DEALINGS IN THE SOFTWARE.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.
Copyright And License
This software is copyright (c) 2024 by Aurelia Peters.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.
perl v5.38.2 2024-05-02 JSON::Path(3pm)
Description
This module implements JSONPath, an XPath-like language for searching JSON-like structures.
JSONPath is described at <http://goessner.net/articles/JsonPath/>.
Constructor
"JSON::Path->new($string)"
Given a JSONPath expression $string, returns a "JSON::Path" object.
Methods
values($object)
Evaluates the JSONPath expression against an object. The object $object can be either a nested Perl
hashref/arrayref structure, or a JSON string capable of being decoded by JSON::MaybeXS::decode_json.
Returns a list of structures from within $object which match against the JSONPath expression. In
scalar context, returns the number of matches.
value($object)
Like "values", but returns just the first value. This method is an lvalue sub, which means you can
assign to it:
my $person = { name => "Robert" };
my $path = JSON::Path->new('$.name');
$path->value($person) = "Bob";
TAKE NOTE! This will create keys in $object. E.G.:
my $obj = { foo => 'bar' };
my $path = JSON::Path->new('$.baz');
$path->value($obj) = 'bak'; # $obj->{baz} is created and set to 'bak';
paths($object)
As per "values" but instead of returning structures which match the expression, returns canonical
JSONPaths that point towards those structures.
get($object)
In list context, identical to "values", but in scalar context returns the first result.
"set($object, $value, $limit)"
Alters $object, setting the paths to $value. If set, then $limit limits the number of changes made.
TAKE NOTE! This will create keys in $object. E.G.:
my $obj = { foo => 'bar' };
my $path = JSON::Path->new('$.baz');
$path->set($obj, 'bak'); # $obj->{baz} is created and set to 'bak'
Returns the number of changes made.
"map($object, $coderef)"
Conceptually similar to Perl's "map" keyword. Executes the coderef (in scalar context!) for each
match of the path within the object, and sets a new value from the coderef's return value. Within the
coderef, $_ may be used to access the old value, and $. may be used to access the curent canonical
JSONPath.
"to_string"
Returns the original JSONPath expression as a string.
This method is usually not needed, as the JSON::Path should automatically stringify itself as
appropriate. i.e. the following works:
my $jpath = JSON::Path->new('$.store.book[*].author');
print "I'm looking for: " . $jpath . "\n";
Functions
The following functions are available for export, but are not exported by default:
"jpath($object, $path_string)"
Shortcut for "JSON::Path->new($path_string)->values($object)".
"jpath1($object, $path_string)"
Shortcut for "JSON::Path->new($path_string)->value($object)". Like "value", it can be used as an
lvalue.
"jpath_map { CODE } $object, $path_string"
Shortcut for "JSON::Path->new($path_string)->map($object, $code)".
Name
JSON::Path - search nested hashref/arrayref structures using JSONPath
Perl Specifics
JSONPath is intended as a cross-programming-language method of searching nested object structures. There
are however, some things you need to think about when using JSONPath in Perl...
JSONPathEmbeddedPerlExpressions
JSONPath expressions may contain subexpressions that are evaluated using the native host language. e.g.
$..book[?($_->{author} =~ /tolkien/i)]
The stuff between "?(" and ")" is a Perl expression that must return a boolean, used to filter results.
As arbitrary Perl may be used, this is clearly quite dangerous unless used in a controlled environment.
Thus, it's disabled by default. To enable, set:
$JSON::Path::Safe = 0;
There are some differences between the JSONPath spec and this implementation.
• JSONPath uses a variable '$' to refer to the root node. This is not a legal variable name in Perl,
so '$root' is used instead.
• JSONPath uses a variable '@' to refer to the current node. This is not a legal variable name in
Perl, so '$_' is used instead.
BlessedObjects
Blessed objects are generally treated as atomic values; JSON::Path will not follow paths inside them. The
exception to this rule are blessed objects where:
Scalar::Util::blessed($object)
&& $object->can('typeof')
&& $object->typeof =~ /^(ARRAY|HASH)$/
which are treated as an unblessed arrayref or hashref appropriately.
See Also
Specification: <http://goessner.net/articles/JsonPath/>.
Implementations in PHP, Javascript and C#: <http://code.google.com/p/jsonpath/>.
Jayway JsonPath: <https://github.com/json-path/JsonPath>
Related modules: JSON, JSON::JOM, JSON::T, JSON::GRDDL, JSON::Hyper, JSON::Schema.
Similar functionality: Data::Path, Data::DPath, Data::SPath, Hash::Path, Path::Resolver::Resolver::Hash,
Data::Nested, Data::Hierarchy... yes, the idea's not especially new. What's different is that JSON::Path
uses a vaguely standardised syntax with implementations in at least three other programming languages.
Synopsis
my $data = {
"store" => {
"book" => [
{ "category" => "reference",
"author" => "Nigel Rees",
"title" => "Sayings of the Century",
"price" => 8.95,
},
{ "category" => "fiction",
"author" => "Evelyn Waugh",
"title" => "Sword of Honour",
"price" => 12.99,
},
{ "category" => "fiction",
"author" => "Herman Melville",
"title" => "Moby Dick",
"isbn" => "0-553-21311-3",
"price" => 8.99,
},
{ "category" => "fiction",
"author" => "J. R. R. Tolkien",
"title" => "The Lord of the Rings",
"isbn" => "0-395-19395-8",
"price" => 22.99,
},
],
"bicycle" => [
{ "color" => "red",
"price" => 19.95,
},
],
},
};
use JSON::Path 'jpath_map';
# All books in the store
my $jpath = JSON::Path->new('$.store.book[*]');
my @books = $jpath->values($data);
# The author of the last (by order) book
my $jpath = JSON::Path->new('$..book[-1:].author');
my $tolkien = $jpath->value($data);
# Convert all authors to uppercase
jpath_map { uc $_ } $data, '$.store.book[*].author';
Version
version 1.0.6
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