(Ruby) 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" }

	
}

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

json = Chilkat::CkJsonObject.new()
json.put_EmitCompact(false)

# Assume the file contains the data as shown above..
success = json.LoadFile("qa_data/json/pathSample.json")
if (success != true)
    print json.lastErrorText() + "\n";
    exit
end

# 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]").to_s() + "\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.put_I(1)
json.put_J(2)
json.put_K(1)
print "This should be 18: " + json.IntOf("nestedArray[i][j][k]").to_s() + "\n";

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

# Now iterate...

for i in 0 .. sz - 1
    json.put_I(i)
    print json.IntOf("nestedArray[1][2][i]").to_s() + "\n";
end

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

# szI should equal 1.
szI = json.SizeOfArray("nestedArray")
for i in 0 .. szI - 1
    json.put_I(i)

    szJ = json.SizeOfArray("nestedArray[i]")
    for j in 0 .. szJ - 1
        json.put_J(j)

        szK = json.SizeOfArray("nestedArray[i][j]")
        for k in 0 .. szK - 1
            json.put_K(k)

            print json.IntOf("nestedArray[i][j][k]").to_s() + "\n";
        end
    end
end

# 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"
# obj2 is a CkJsonObject
obj2 = json.ObjectOf("mixture.arrayA[1]")
# 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:
# arr1 is a CkJsonArray
arr1 = json.ArrayOf("mixture.arrayA[0].colors")
szArr1 = arr1.get_Size()
for i in 0 .. szArr1 - 1
    print i.to_s() + ": " + arr1.stringAt(i) + "\n";
end

# 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";