Javascript like objects and JSON processing in VBA

Javascript like objects and JSON processing in VBA

cJobject primer from Excel Liberation

http://ramblings.mcpher.com/

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



Javascript object versus cJobjectVBA 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").addArray

Add an array element object

f.push({family:{name:”Flintstone”,wife:”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()



PortabilityThe 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();



IterationHow to iterate through cJobject children. Examples - vba

for each joc in job.children

Debug.Print job.key,job.value

next jocExamples - 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]);

}



RecursionSince 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



ExtensibilityEasy to extend with powerful capabilitiesExamples

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 characters.1.family.nameFind 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 ......



ChainingThe cJobect is designed to be chainableExamples – VBA

With .add.add("module") .add "name", module.name .add "kind", module.textKind With .add("procedures").addArray For Each procedure In module.procedures With .add.add("procedure") .add "name", procedure.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", argument.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



Custom classes and sub classesCreating 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()



‘Javascript like’ optional argumentsIt’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 optionsreshapeMelt "{'outputSheet':'meltOut','id':['id','time']}“-------------Public Function rOptionDefaults() As String ‘ the default options.. rOptionDefaults = _ "{'complain':true, 'inputSheet':'" & ActiveSheet.name & "'," & _ "'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



Memory recoveryLike 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



SummaryThese examples show some of the capabilities

of cJObect and bringing a JSON capability to Excel

For more detail, and to download see Excel Liberation


http://www.mcpher.com/

Javascript like objects and JSON processing in VBA

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