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Using Pre-defined JSON Templates

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Demonstrates how to predefine a JSON template, and then use it to emit JSON with variable substitutions.

Note: This example requires Chilkat v9.5.0.67 or greater.

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; One way to create JSON is to do it in a straightforward manner:
$oJson = ObjCreate("Chilkat.JsonObject")
$oJson.EmitCompact = False
$oJson.UpdateString("id","0001")
$oJson.UpdateString("type","donut")
$oJson.UpdateString("name","Cake")
$oJson.UpdateString("image.url","images/0001.jpg")
$oJson.UpdateInt("image.width",200)
$oJson.UpdateInt("image.height",200)
$oJson.UpdateString("thumbnail.url","images/thumbnails/0001.jpg")
$oJson.UpdateInt("thumbnail.width",32)
$oJson.UpdateInt("thumbnail.height",32)
ConsoleWrite($oJson.Emit() & @CRLF)

; The JSON created by the above code:

; 	{ 
; 	  "id": "0001",
; 	  "type": "donut",
; 	  "name": "Cake",
; 	  "image": { 
; 	    "url": "images/0001.jpg",
; 	    "width": 200,
; 	    "height": 200
; 	  },
; 	  "thumbnail": { 
; 	    "url": "images/thumbnails/0001.jpg",
; 	    "width": 32,
; 	    "height": 32
; 	  }
; 	}

; An alternative is to predefine a template, and then use it to emit with variable substitutions.
; For example:

$oJsonTemplate = ObjCreate("Chilkat.JsonObject")
$oJsonTemplate.UpdateString("id","{$id}")
$oJsonTemplate.UpdateString("type","donut")
$oJsonTemplate.UpdateString("name","{$name}")
$oJsonTemplate.UpdateString("image.url","{$imageUrl}")
; The "i." indicates that it's an integer variable.
$oJsonTemplate.UpdateString("image.width","{$i.imageWidth}")
$oJsonTemplate.UpdateString("image.height","{$i.imageHeight}")
$oJsonTemplate.UpdateString("thumbnail.url","{$thumbUrl}")
$oJsonTemplate.UpdateString("thumbnail.width","{$i.thumbWidth}")
$oJsonTemplate.UpdateString("thumbnail.height","{$i.thumbHeight}")
; Give this template a name.
$oJsonTemplate.Predefine("donut")

; --------------------------------------------------------------------------
; OK, the template is defined.  Defining a template can be done once
; at the start of your program, and you can discard the jsonTemplate object (it
; doesn't need to stick around..)

; Now we can create instances of the JSON object by name:
$oJsonDonut = ObjCreate("Chilkat.JsonObject")
$oJsonDonut.EmitCompact = False
$oJsonDonut.LoadPredefined("donut")
ConsoleWrite($oJsonDonut.Emit() & @CRLF)

; The output is this:

; 	{ 
; 	  "id": "{$id}",
; 	  "type": "donut",
; 	  "name": "{$name}",
; 	  "image": { 
; 	    "url": "{$imageUrl}",
; 	    "width": "{$i.imageWidth}",
; 	    "height": "{$i.imageHeight}"
; 	  },
; 	  "thumbnail": { 
; 	    "url": "{$thumbUrl}",
; 	    "width": "{$i.thumbWidth}",
; 	    "height": "{$i.thumbHeight}"
; 	  }
; 	}

; Finally, we can substitute variables like this:
$oDonutValues = ObjCreate("Chilkat.Hashtable")
$oDonutValues.AddStr("id","0001")
$oDonutValues.AddStr("name","Cake")
$oDonutValues.AddStr("imageUrl","images/0001.jpg")
$oDonutValues.AddInt("imageWidth",200)
$oDonutValues.AddInt("imageHeight",200)
$oDonutValues.AddStr("thumbUrl","images/thumbnails/0001.jpg")
$oDonutValues.AddInt("thumbWidth",32)
$oDonutValues.AddInt("thumbHeight",32)

; Emit with variable substitutions:
Local $bOmitEmpty = True
ConsoleWrite($oJsonDonut.EmitWithSubs($oDonutValues,$bOmitEmpty) & @CRLF)

; Output:

; 	{ 
; 	  "id": "0001",
; 	  "type": "donut",
; 	  "name": "Cake",
; 	  "image": { 
; 	    "url": "images/0001.jpg",
; 	    "width": 200,
; 	    "height": 200
; 	  },
; 	  "thumbnail": { 
; 	    "url": "images/thumbnails/0001.jpg",
; 	    "width": 32,
; 	    "height": 32
; 	  }
; 	}

; Change some of the values:
$oDonutValues.AddStr("id","0002")
$oDonutValues.AddStr("imageUrl","images/0002.jpg")
$oDonutValues.AddStr("thumbUrl","images/thumbnails/0002.jpg")

ConsoleWrite($oJsonDonut.EmitWithSubs($oDonutValues,$bOmitEmpty) & @CRLF)

; Output:

; 	{ 
; 	  "id": "0002",
; 	  "type": "donut",
; 	  "name": "Cake",
; 	  "image": { 
; 	    "url": "images/0002.jpg",
; 	    "width": 200,
; 	    "height": 200
; 	  },
; 	  "thumbnail": { 
; 	    "url": "images/thumbnails/0002.jpg",
; 	    "width": 32,
; 	    "height": 32
; 	  }
; 	}