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(Excel) Using Pre-defined JSON TemplatesDemonstrates 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.
' One way to create JSON is to do it in a straightforward manner: Dim json As Chilkat.JsonObject Set json = Chilkat.NewJsonObject json.EmitCompact = False Dim success As Boolean success = json.UpdateString("id","0001") success = json.UpdateString("type","donut") success = json.UpdateString("name","Cake") success = json.UpdateString("image.url","images/0001.jpg") success = json.UpdateInt("image.width",200) success = json.UpdateInt("image.height",200) success = json.UpdateString("thumbnail.url","images/thumbnails/0001.jpg") success = json.UpdateInt("thumbnail.width",32) success = json.UpdateInt("thumbnail.height",32) Debug.Print 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: Dim jsonTemplate As Chilkat.JsonObject Set jsonTemplate = Chilkat.NewJsonObject success = jsonTemplate.UpdateString("id","{$id}") success = jsonTemplate.UpdateString("type","donut") success = jsonTemplate.UpdateString("name","{$name}") success = jsonTemplate.UpdateString("image.url","{$imageUrl}") ' The "i." indicates that it's an integer variable. success = jsonTemplate.UpdateString("image.width","{$i.imageWidth}") success = jsonTemplate.UpdateString("image.height","{$i.imageHeight}") success = jsonTemplate.UpdateString("thumbnail.url","{$thumbUrl}") success = jsonTemplate.UpdateString("thumbnail.width","{$i.thumbWidth}") success = jsonTemplate.UpdateString("thumbnail.height","{$i.thumbHeight}") ' Give this template a name. success = 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: Dim jsonDonut As Chilkat.JsonObject Set jsonDonut = Chilkat.NewJsonObject jsonDonut.EmitCompact = False success = jsonDonut.LoadPredefined("donut") Debug.Print 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: Dim donutValues As Chilkat.Hashtable Set donutValues = Chilkat.NewHashtable success = donutValues.AddStr("id","0001") success = donutValues.AddStr("name","Cake") success = donutValues.AddStr("imageUrl","images/0001.jpg") success = donutValues.AddInt("imageWidth",200) success = donutValues.AddInt("imageHeight",200) success = donutValues.AddStr("thumbUrl","images/thumbnails/0001.jpg") success = donutValues.AddInt("thumbWidth",32) success = donutValues.AddInt("thumbHeight",32) ' Emit with variable substitutions: omitEmpty = True Debug.Print jsonDonut.EmitWithSubs(donutValues,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: success = donutValues.AddStr("id","0002") success = donutValues.AddStr("imageUrl","images/0002.jpg") success = donutValues.AddStr("thumbUrl","images/thumbnails/0002.jpg") Debug.Print jsonDonut.EmitWithSubs(donutValues,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 ' } ' } |
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