JSON::Path3pm

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)".

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.

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.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.