PowerBuilder

Using Pre-defined JSON Templates

See more JSON Examples

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.

PowerBuilder

integer li_rc
oleobject loo_Json
oleobject loo_JsonTemplate
oleobject loo_JsonDonut
oleobject loo_DonutValues
integer li_OmitEmpty

// One way to create JSON is to do it in a straightforward manner:
loo_Json = create oleobject
li_rc = loo_Json.ConnectToNewObject("Chilkat.JsonObject")
if li_rc < 0 then
    destroy loo_Json
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Json.EmitCompact = 0
loo_Json.UpdateString("id","0001")
loo_Json.UpdateString("type","donut")
loo_Json.UpdateString("name","Cake")
loo_Json.UpdateString("image.url","images/0001.jpg")
loo_Json.UpdateInt("image.width",200)
loo_Json.UpdateInt("image.height",200)
loo_Json.UpdateString("thumbnail.url","images/thumbnails/0001.jpg")
loo_Json.UpdateInt("thumbnail.width",32)
loo_Json.UpdateInt("thumbnail.height",32)
Write-Debug loo_Json.Emit()

// 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:

loo_JsonTemplate = create oleobject
li_rc = loo_JsonTemplate.ConnectToNewObject("Chilkat.JsonObject")

loo_JsonTemplate.UpdateString("id","{$id}")
loo_JsonTemplate.UpdateString("type","donut")
loo_JsonTemplate.UpdateString("name","{$name}")
loo_JsonTemplate.UpdateString("image.url","{$imageUrl}")
// The "i." indicates that it's an integer variable.
loo_JsonTemplate.UpdateString("image.width","{$i.imageWidth}")
loo_JsonTemplate.UpdateString("image.height","{$i.imageHeight}")
loo_JsonTemplate.UpdateString("thumbnail.url","{$thumbUrl}")
loo_JsonTemplate.UpdateString("thumbnail.width","{$i.thumbWidth}")
loo_JsonTemplate.UpdateString("thumbnail.height","{$i.thumbHeight}")
// Give this template a name.
loo_JsonTemplate.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:
loo_JsonDonut = create oleobject
li_rc = loo_JsonDonut.ConnectToNewObject("Chilkat.JsonObject")

loo_JsonDonut.EmitCompact = 0
loo_JsonDonut.LoadPredefined("donut")
Write-Debug loo_JsonDonut.Emit()

// 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:
loo_DonutValues = create oleobject
li_rc = loo_DonutValues.ConnectToNewObject("Chilkat.Hashtable")

loo_DonutValues.AddStr("id","0001")
loo_DonutValues.AddStr("name","Cake")
loo_DonutValues.AddStr("imageUrl","images/0001.jpg")
loo_DonutValues.AddInt("imageWidth",200)
loo_DonutValues.AddInt("imageHeight",200)
loo_DonutValues.AddStr("thumbUrl","images/thumbnails/0001.jpg")
loo_DonutValues.AddInt("thumbWidth",32)
loo_DonutValues.AddInt("thumbHeight",32)

// Emit with variable substitutions:
li_OmitEmpty = 1
Write-Debug loo_JsonDonut.EmitWithSubs(loo_DonutValues,li_OmitEmpty)

// 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:
loo_DonutValues.AddStr("id","0002")
loo_DonutValues.AddStr("imageUrl","images/0002.jpg")
loo_DonutValues.AddStr("thumbUrl","images/thumbnails/0002.jpg")

Write-Debug loo_JsonDonut.EmitWithSubs(loo_DonutValues,li_OmitEmpty)

// 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
// 	  }
// 	}


destroy loo_Json
destroy loo_JsonTemplate
destroy loo_JsonDonut
destroy loo_DonutValues