Javascript like objects and JSON processing in VBA


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the cJobject brings javascript like objects if indeterminate depth to Excel/VBA, (along with the ability to create or parse JSON)

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Javascript like objects and JSON processing in VBA

  1. 1. Javascript like objects and JSON processing in VBA cJobject primer from Excel Liberation
  2. 2. Excel Liberation for details cJobject purpose The Excel/VBA model is optimized for 2 dimensions (rows/columns) – or at best 3 (sheets/rows/columns) { "Flintstone Characters": { "families": [ { "family": { "name": "FlintStone", "wife": "Wilma", "husband": "Fred", "kids": [ "Pebbles" ], "pets": [ "Baby Puss", "Dino", "Doozy" ] } }, { "family": { "name": "Rubble", "wife": "Betty", "husband": "Barney", "kids": [ "Bam Bam" ], "pets": [ "Hoppy" ] } } ] } } Data from web sources can be any depth. VBA lacked the capability to deal with either the format or the structure of JSON data. cJobject provides both the structure and data handling capability
  3. 3. Excel Liberation for details Javascript object versus cJobject VBA lacks the syntax to express such an object as concisely as javascript,but a similar capability can be achieved with cJobjectAction javaScript cJobject New object var job = {}; Set job = new cJobect Create from JSON var job = JSON.parse(str); Set job = JSONParse(str) Add a property job["Flintstone Characters”] = null; job.add ("Flintstone Characters”) Add an array var f = job["Flintstone Characters”] ={families:[]}; Set f = job.child("Flintstone Characters").add("families").addArr ay Add an array element object f.push({family:{name:”Flintstone”,wi fe:”Wilma”,husband:”Fred”}); With f.add.add("family") .add "name", "FlintStone" .add "wife", "Wilma" .add "husband", "Fred“ End with Convert to JSON JSON.stringify(job); JSONstringify(job) ..or.. job.stringify()
  4. 4. Excel Liberation for details Portability The Google Apps Script version of cJobject has the same syntax (allowing for minor javaScript/VBA linguistic differences) Examples – Google Apps Script var job = new cJobject(); job.add ("Flintstone Characters”); var f = job.child("Flintstone Characters").add("families").addArray(); The cJobject is not really needed in GAS, since js can do this natively. But using cJobject in GAS allows portability to and from VBA. There are also native conversions for GAS available Examples – Google Apps Script var job = fromNative(someObject); var someObject = job.toNative();
  5. 5. Excel Liberation for details Iteration How to iterate through cJobject children. Examples - vba for each joc in job.children Debug.Print job.key,job.value next joc Examples - gas job.children().forEach( function (joc) { Logger.log (job.key() + “,” + job.value()); }); Equivalent in native javaScript Examples var jsObject = job.toNative(); for (k in jsObject ) { console.log(k + “,” + jsObject [k]); }
  6. 6. Excel Liberation for details Recursion Since cJobjects are of inderminate depth, recursion is used internally in the class and they are ideally suited for recursive usage. Here‟s an example of traversing and printing an entire object tree irrespective of the data structure. Examples Public Function printFlint(Optional job As cJobject = Nothing, _ Optional depth As Long = 0) Dim joc As cJobject If (job Is Nothing) Then Set job = getFlintsoneCharacters() Debug.Print Space(depth); job.key; ":"; job.value depth = depth + 2 For Each joc In job.children depth = printFlint(joc, depth) Next joc printFlint = depth - 2 End Function Flintstone Characters: families: 1: family: name:FlintStone wife:Wilma husband:Fred kids: 1:Pebbles pets: saber tooth tiger:Baby Puss dinosaur type dog thing:Dino dodo bird:Doozy 2: family: name:Rubble wife:Betty husband:Barney kids: 1:Bam Bam pets: kangaroo type thing:Hoppy
  7. 7. Excel Liberation for details Extensibility Easy to extend with powerful capabilities Examples Populate a data set with JSON data dSet.populateJSON jobject, Range("json1!$a$1") Read a worksheet into a dset and convert it to JSON dSet.populateData( Range("jSon2!$a$1"), , , , , , True).jObject.stringify() Get the fullkey of any item job.fullKey() – eg Flintstones Find a property somewhere set wilma = job.find(“Wilma”) Make a treeview from a cJobject contents to display on a form set t= job. toTreeView(treeViewObject) Access data returned from a rest API query With restQuery(worksheetName, "my society", , "postcode", _ , , , False, False) For Each job In .jObject.children ......
  8. 8. Excel Liberation for details Chaining The cJobect is designed to be chainable Examples – VBA With .add.add("module") .add "name", .add "kind", module.textKind With .add("procedures").addArray For Each procedure In module.procedures With .add.add("procedure") .add "name", .add "scope", procedure.scope .add "kind", procedure.procTextKind .add "returns", procedure.procReturns .add "lineCount", procedure.lineCount .add "declaration", procedure.declaration With .add("arguments").addArray For Each argument In procedure.arguments With .add.add("argument") .add "name", .add "optional", argument.isOptional .add "default", argument.default .add "argtype", argument.argType End With Next argument End With End With Next procedure End With End With
  9. 9. Excel Liberation for details Custom classes and sub classes Creating classes in VBA requires preknowledge about the class and its properties. The cJobject can be used to create classes „on the fly‟ to avoid cluttering the source code with many small classes Examples With job.init(Nothing, "Flintstone Characters").add("families").addArray With .add.add("family") .add "name", "FlintStone" .add "wife", "Wilma" .add "husband", "Fred" With .add("kids").addArray .add , "Pebbles" End With With .add("pets").addArray .add "saber tooth tiger", "Baby Puss" .add "dinosaur type dog thing", "Dino" .add "dodo bird", "Doozy" End With End With End with Set clone = job.clone()
  10. 10. Excel Liberation for details ‘Javascript like’ optional arguments It‟s very useful in javascript to be able to pass a single argument to a function containing options and other data. The cJobject allows you do the something similar in VBA Examples .. Calling with a couple of non default options reshapeMelt "{'outputSheet':'meltOut','id':['id','time']}“ ------------- Public Function rOptionDefaults() As String „ the default options.. rOptionDefaults = _ "{'complain':true, 'inputSheet':'" & & "'," & _ "'variableColumn' : 'variable', 'valueColumn' : 'value', 'id':['id'] ," & _ "'outputSheet': 'rOutputData' , 'clearContents':true}" End Function Public Function reshapeMelt(options As String) As cDataSet „... Applies default options and meges with given options Set jArgs = optionsExtend(options, rOptionDefaults) ' use the options... With jArgs If .toString("inputsheet") = .toString("outputsheet") Then MsgBox ("Reading and writing to the same sheet - not allowed") Exit Function End If End With
  11. 11. Excel Liberation for details Memory recovery Like many objects with recursive linking, memory will not be recovered by the VBA garbage collector simply by going out of scope. A teardown is provided, and should be used for efficient memory recovery. Examples With JSONparse(str) for each joc in .children Debug.Print joc.value next joc .teardown End With
  12. 12. Excel Liberation for details Summary These examples show some of the capabilities of cJObect and bringing a JSON capability to Excel For more detail, and to download see Excel Liberation