Perl

JSON Paths

See more JSON Examples

Demonstrates using "Chilkat JSON Paths" to access parts of a JSON document, or to iterate over parts.

This example uses the following JSON document:

{
    "nestedArray" : [
			[
				[1,2,3],
				[4,5,6],
				[7,8,9,10]
			],
			[
				[11,12,13],
				[14,15,16],
				[17,18,19,20]
			],
			[
				[21,22,23],
				[24,25,26],
				[27,28,29,30],
				[31,32,33,34,35,36]
			]
		],

	"nestedObject" : {
		"aaa" : {
			"bb1" : {
				"cc1" : "c1Value",
				"cc2" : "c2Value",
				"cc3" : "c3Value"
			},
			"bb2" : {
				"dd1" : "d1Value",
				"dd2" : "d2Value",
				"dd3" : "d3Value"
			}
		}
	},

	"mixture" : {
		"arrayA" : [  
			{ "fruit": "apple", "animal": "horse", "job": "fireman", "colors": ["red","blue","green"] },
			{ "fruit": "pear", "animal": "plankton", "job": "waiter", "colors": ["yellow","orange","purple"] },
			{ "fruit": "kiwi", "animal": "echidna", "job": "astronaut", "colors": ["magenta","tan","pink"] }
			]
	},


        "name.with.dots" : { "grain" : "oats" }

	
}

Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

my $json = Chilkat2::JsonObject->new;
$json->EmitCompact(0);

# Assume the file contains the data as shown above..
my $success = $json->LoadFile('qa_data/json/pathSample.json');
if (!$success) {
    print $json->LastErrorText, "\n";
    exit;
}

# First, let's get the value of "cc1"
# The path to this value is: nestedObject.aaa.bb1.cc1
print $json->StringOf('nestedObject.aaa.bb1.cc1'), "\n";

# Now let's get number 18 from the nestedArray.
# It is located at nestedArray[1][2][1]
# (remember: Indexing is 0-based)
print 'This should be 18: ', $json->IntOf('nestedArray[1][2][1]'), "\n";

# We can do the same thing in a more roundabout way using the
# I, J, and K properties.  (The I,J,K properties will be convenient
# for iterating over arrays, as we'll see later.)
$json->I(1);
$json->J(2);
$json->K(1);
print 'This should be 18: ', $json->IntOf('nestedArray[i][j][k]'), "\n";

# Let's iterate over the array containing the numbers 17, 18, 19, 20.
# First, use the SizeOfArray method to get the array size:
my $sz = $json->SizeOfArray('nestedArray[1][2]');
# The size should be 4.
print 'size of array = ', $sz, " (should equal 4)\n";

# Now iterate...
for my $i (0 .. $sz - 1) {
    $json->I($i);
    print $json->IntOf('nestedArray[1][2][i]'), "\n";
}

# Let's use a triple-nested loop to iterate over the nestedArray:

# szI should equal 1.
my $szI = $json->SizeOfArray('nestedArray');
for my $i (0 .. $szI - 1) {
    $json->I($i);

    my $szJ = $json->SizeOfArray('nestedArray[i]');
    for my $j (0 .. $szJ - 1) {
        $json->J($j);

        my $szK = $json->SizeOfArray('nestedArray[i][j]');
        for my $k (0 .. $szK - 1) {
            $json->K($k);

            print $json->IntOf('nestedArray[i][j][k]'), "\n";
        }
    }
}

# Now let's examine how to navigate to JSON objects contained within JSON arrays.
# This line of code gets the value "kiwi" contained within "mixture"
print $json->StringOf('mixture.arrayA[2].fruit'), "\n";

# This line of code gets the color "yellow"
print $json->StringOf('mixture.arrayA[1].colors[0]'), "\n";

# Getting an object at a path:
# This gets the 2nd object in "arrayA"

my $obj2 = Chilkat2::JsonObject->new;
$json->ObjectOf2('mixture.arrayA[1]', $obj2);

# This object's "animal" should be "plankton"
print $obj2->StringOf('animal'), "\n";

# Note that paths are relative to the object, not the absolute root of the JSON document.
# Starting from obj2, "purple" is at "colors[2]"
print $obj2->StringOf('colors[2]'), "\n";

# Getting an array at a path:
# This gets the array containing the colors red, green, blue:

my $arr1 = Chilkat2::JsonArray->new;
$json->ArrayOf2('mixture.arrayA[0].colors', $arr1);

my $szArr1 = $arr1->Size;
for my $i (0 .. $szArr1 - 1) {
    print $i, ': ', $arr1->StringAt($i), "\n";
}

# The Chilkat JSON path uses ".", "[", and "]" chars for separators.  When a name
# contains one of these chars, use double-quotes in the path:
print $json->StringOf('"name.with.dots".grain'), "\n";