(Node.js) JSON Paths

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" }

	
}

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    var json = new chilkat.JsonObject();
    json.EmitCompact = false;

    // Assume the file contains the data as shown above..
    var success = json.LoadFile("qa_data/json/pathSample.json");
    if (success !== true) {
        console.log(json.LastErrorText);
        return;
    }

    // First, let's get the value of "cc1"
    // The path to this value is: nestedObject.aaa.bb1.cc1
    console.log(json.StringOf("nestedObject.aaa.bb1.cc1"));

    // Now let's get number 18 from the nestedArray.
    // It is located at nestedArray[1][2][1]
    // (remember: Indexing is 0-based)
    console.log("This should be 18: " + json.IntOf("nestedArray[1][2][1]"));

    // 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;
    console.log("This should be 18: " + json.IntOf("nestedArray[i][j][k]"));

    // Let's iterate over the array containing the numbers 17, 18, 19, 20.
    // First, use the SizeOfArray method to get the array size:
    var sz = json.SizeOfArray("nestedArray[1][2]");
    // The size should be 4.
    console.log("size of array = " + sz + " (should equal 4)");

    // Now iterate...
    var i;
    for (i = 0; i <= sz - 1; i++) {
        json.I = i;
        console.log(json.IntOf("nestedArray[1][2][i]"));
    }

    // Let's use a triple-nested loop to iterate over the nestedArray:
    var j;
    var k;

    // szI should equal 1.
    var szI = json.SizeOfArray("nestedArray");
    for (i = 0; i <= szI - 1; i++) {
        json.I = i;

        var szJ = json.SizeOfArray("nestedArray[i]");
        for (j = 0; j <= szJ - 1; j++) {
            json.J = j;

            var szK = json.SizeOfArray("nestedArray[i][j]");
            for (k = 0; k <= szK - 1; k++) {
                json.K = k;

                console.log(json.IntOf("nestedArray[i][j][k]"));
            }

        }

    }

    // 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"
    console.log(json.StringOf("mixture.arrayA[2].fruit"));

    // This line of code gets the color "yellow"
    console.log(json.StringOf("mixture.arrayA[1].colors[0]"));

    // Getting an object at a path:
    // This gets the 2nd object in "arrayA"
    // obj2: JsonObject
    var obj2 = json.ObjectOf("mixture.arrayA[1]");
    // This object's "animal" should be "plankton"
    console.log(obj2.StringOf("animal"));

    // Note that paths are relative to the object, not the absolute root of the JSON document.
    // Starting from obj2, "purple" is at "colors[2]"
    console.log(obj2.StringOf("colors[2]"));

    // Getting an array at a path:
    // This gets the array containing the colors red, green, blue:
    // arr1: JsonArray
    var arr1 = json.ArrayOf("mixture.arrayA[0].colors");
    var szArr1 = arr1.Size;
    for (i = 0; i <= szArr1 - 1; i++) {
        console.log(i + ": " + arr1.StringAt(i));
    }

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

}

chilkatExample();