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https://github.com/tobyink/p5-json-path

Last synced: about 2 months ago
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Host: GitHub
URL: https://github.com/tobyink/p5-json-path
Owner: tobyink
Created: 2013-02-12T20:38:53.000Z (almost 12 years ago)
Default Branch: master
Last Pushed: 2022-09-01T03:21:38.000Z (over 2 years ago)
Last Synced: 2024-06-02T14:42:39.056Z (7 months ago)
Language: Perl
Size: 327 KB
Stars: 2
Watchers: 3
Forks: 12
Open Issues: 8
Metadata Files:
- Readme: README.md
- Changelog: Changes
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README

        # NAME

JSON::Path

# VERSION

version 0.420

# 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';

# DESCRIPTION

This module implements JSONPath, an XPath-like language for searching

JSON-like structures.

JSONPath is described at [http://goessner.net/articles/JsonPath/](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...

## JSONPath Embedded Perl Expressions

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.

## Blessed Objects

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.

# BUGS

Please report any bugs to [http://rt.cpan.org/](http://rt.cpan.org/).

# SEE ALSO

Specification: [http://goessner.net/articles/JsonPath/](http://goessner.net/articles/JsonPath/).

Implementations in PHP, Javascript and C#:

[http://code.google.com/p/jsonpath/](http://code.google.com/p/jsonpath/).

Related modules: [JSON](https://metacpan.org/pod/JSON), [JSON::JOM](https://metacpan.org/pod/JSON::JOM), [JSON::T](https://metacpan.org/pod/JSON::T), [JSON::GRDDL](https://metacpan.org/pod/JSON::GRDDL),

[JSON::Hyper](https://metacpan.org/pod/JSON::Hyper), [JSON::Schema](https://metacpan.org/pod/JSON::Schema).

Similar functionality: [Data::Path](https://metacpan.org/pod/Data::Path), [Data::DPath](https://metacpan.org/pod/Data::DPath), [Data::SPath](https://metacpan.org/pod/Data::SPath),

[Hash::Path](https://metacpan.org/pod/Hash::Path), [Path::Resolver::Resolver::Hash](https://metacpan.org/pod/Path::Resolver::Resolver::Hash), [Data::Nested](https://metacpan.org/pod/Data::Nested),

[Data::Hierarchy](https://metacpan.org/pod/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.

# AUTHOR

Toby Inkster .

# MAINTAINER

Kit Peters 

# CONTRIBUTORS

Szymon Nieznański  

Kit Peters 

Heiko Jansen .

Mitsuhiro Nakamura 

Patrick Cronin 

# COPYRIGHT AND LICENCE

Copyright 2007 Stefan Goessner.

Copyright 2010-2013 Toby Inkster.

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. "The MIT Licence"

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.

# AUTHOR

Kit Peters 

# COPYRIGHT AND LICENSE

This software is copyright (c) 2016 by Kit 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.