Xbase++

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" }

	
}

Xbase++

LOCAL nSuccess
LOCAL oJson
LOCAL nSz
LOCAL i
LOCAL j
LOCAL k
LOCAL nSzI
LOCAL nSzJ
LOCAL nSzK
LOCAL oObj2
LOCAL oArr1
LOCAL nSzArr1

nSuccess := 0

oJson := CreateObject("Chilkat.JsonObject")
oJson:EmitCompact := 0

//  Assume the file contains the data as shown above..
nSuccess := oJson:LoadFile("qa_data/json/pathSample.json")
IF (nSuccess == 0)
    ? oJson:LastErrorText
    oJson:destroy()
    RETURN
ENDIF

//  First, let's get the value of "cc1"
//  The path to this value is: nestedObject.aaa.bb1.cc1
? oJson: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)
? "This should be 18: " + Str(oJson: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.)
oJson:I := 1
oJson:J := 2
oJson:K := 1
? "This should be 18: " + Str(oJson: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:
nSz := oJson:SizeOfArray("nestedArray[1][2]")
//  The size should be 4.
? "size of array = " + Str(nSz) + " (should equal 4)"

//  Now iterate...

FOR i := 0 TO nSz - 1
    oJson:I := i
    ? Str(oJson:IntOf("nestedArray[1][2][i]"))
NEXT

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

//  szI should equal 1.
nSzI := oJson:SizeOfArray("nestedArray")
FOR i := 0 TO nSzI - 1
    oJson:I := i

    nSzJ := oJson:SizeOfArray("nestedArray[i]")
    FOR j := 0 TO nSzJ - 1
        oJson:J := j

        nSzK := oJson:SizeOfArray("nestedArray[i][j]")
        FOR k := 0 TO nSzK - 1
            oJson:K := k

            ? Str(oJson:IntOf("nestedArray[i][j][k]"))
        NEXT
    NEXT
NEXT

//  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"
? oJson:StringOf("mixture.arrayA[2].fruit")

//  This line of code gets the color "yellow"
? oJson:StringOf("mixture.arrayA[1].colors[0]")

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

oObj2 := CreateObject("Chilkat.JsonObject")
oJson:ObjectOf2("mixture.arrayA[1]", oObj2)

//  This object's "animal" should be "plankton"
? oObj2: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]"
? oObj2:StringOf("colors[2]")

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

oArr1 := CreateObject("Chilkat.JsonArray")
oJson:ArrayOf2("mixture.arrayA[0].colors", oArr1)

nSzArr1 := oArr1:Size
FOR i := 0 TO nSzArr1 - 1
    ? Str(i) + ": " + oArr1:StringAt(i)
NEXT

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

oJson:destroy()
oObj2:destroy()
oArr1:destroy()