(Go) 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" }

	
}

Note: This example requires Chilkat v11.0.0 or greater.

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    success := false

    json := JsonObject_Ref.html">chilkat.NewJsonObject()
    json.SetEmitCompact(false)

    // Assume the file contains the data as shown above..
    success = json.LoadFile("qa_data/json/pathSample.json")
    if success == false {
        fmt.Println(json.LastErrorText())
        json.DisposeJsonObject()
        return
    }

    // First, let's get the value of "cc1"
    // The path to this value is: nestedObject.aaa.bb1.cc1
    fmt.Println(*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)
    fmt.Println("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.SetI(1)
    json.SetJ(2)
    json.SetK(1)
    fmt.Println("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:
    sz := json.SizeOfArray("nestedArray[1][2]")
    // The size should be 4.
    fmt.Println("size of array = ", sz, " (should equal 4)")

    // Now iterate...
    var i int
    for i = 0; i <= sz - 1; i++ {
        json.SetI(i)
        fmt.Println(json.IntOf("nestedArray[1][2][i]"))
    }

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

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

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

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

                fmt.Println(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"
    fmt.Println(*json.StringOf("mixture.arrayA[2].fruit"))

    // This line of code gets the color "yellow"
    fmt.Println(*json.StringOf("mixture.arrayA[1].colors[0]"))

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

    obj2 := JsonObject_Ref.html">chilkat.NewJsonObject()
    json.ObjectOf2("mixture.arrayA[1]",obj2)

    // This object's "animal" should be "plankton"
    fmt.Println(*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]"
    fmt.Println(*obj2.StringOf("colors[2]"))

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

    arr1 := JsonArray_Ref.html">chilkat.NewJsonArray()
    json.ArrayOf2("mixture.arrayA[0].colors",arr1)

    szArr1 := arr1.Size()
    for i = 0; i <= szArr1 - 1; i++ {
        fmt.Println(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:
    fmt.Println(*json.StringOf("\"name.with.dots\".grain"))

    json.DisposeJsonObject()
    obj2.DisposeJsonObject()
    arr1.DisposeJsonArray()