Perl

Get the Index of a JSON Member

See more JSON Examples

This example demonstrates how to get the index of a given member by name.

{
  "name": "donut",
  "image":
    {
    "fname": "donut.jpg",
    "w": 200,
    "h": 200
    },
  "thumbnail":
    {
    "fname": "donutThumb.jpg",
    "w": 32,
    "h": 32
    }
}

Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

my $json = Chilkat2::JsonObject->new;

# This is the above JSON with whitespace chars removed (SPACE, TAB, CR, and LF chars).
# The presence of whitespace chars for pretty-printing makes no difference to the Load
# method.
my $jsonStr = '{"name": "donut","image":{"fname": "donut.jpg","w": 200,"h": 200},"thumbnail":{"fname": "donutThumb.jpg","w": 32,"h": 32}}';

my $success = $json->Load($jsonStr);
if (!$success) {
    print $json->LastErrorText, "\n";
    exit;
}

# The top-level JSON object has three members: name, image, and thumbnail.
my $nameIndex = $json->IndexOf('name');
# The index of the "name" member is 0.
print 'nameIndex = ', $nameIndex, "\n";

my $thumbIndex = $json->IndexOf('thumbnail');
# The index of the "thumbnail" member is 2.
print 'thumbIndex = ', $thumbIndex, "\n";

# The "fname" member is NOT a direct member of the top-level JSON object.
# It is a member of a nested object.  If we try to get the index of this
# member using the top-level JSON object, it is not found (and returns -1).
my $fnameIndex = $json->IndexOf('fname');
# The fnameIndex is -1 (not found).  This is correct.
print 'fnameIndex = ', $fnameIndex, "\n";

# Get the "image" object.
my $imageObj = Chilkat2::JsonObject->new;
$json->ObjectOf2('image', $imageObj);

# Now we can get the index of the "fname" object, because it is a direct
# member of the "image" object:
$fnameIndex = $imageObj->IndexOf('fname');
print 'fnameIndex = ', $fnameIndex, "\n";