Extracting results from an API call with a VBA function - json

Question

I'm just starting to work with JSON in one of my macros. I'm able to send a call to an API service and it returns results. The service has been set up to return something like 25 fields (?). I don't need all of the fields, just some of them. The macro uses VBA.
I'm able to write the results to a specific worksheet with the following code:
For Each result In jsonObject
With Sheets("Sheet1")
.Cells(r, 5).Value = result("firstName")
.Cells(r, 6).Value = result("lastName")
.Cells(r, 9).Value = result("userCodeInfo")("userCode")
.Cells(r, 10).Value = result("userCodeInfo")("previousUserCode")
.Cells(r, 28).Value = result("saleType")
.Cells(r, 29).Value = result("cost")
End With
Next
Later, in the code, a decision point needs to use to one of the fields in the results. I'm trying to use a function to return that field value:
Public Function APIUnitData_Read(MyField As String)
Dim JSONConverter As New clsJSONParser
Set jsonObject = JSONConverter.ParseJson(UnitResp)
For Each result In jsonObject
APIUnitData_Read = result(MyField)
Next
End Function
The function works well when the field is a "non-grouped" field, e.g., "firstName, "lastName", etc.
vDecPt = API.APIUnitData_Read("firstName")
It doesn't work (or at least I haven't gotten it to work with the "grouped" fields; e.g., ("userCodeInfo")("userCode") and ("userCodeInfo")("previousUserCode").
vDecPt = API.APIUnitData_Read("userCodeInfo")("PreviousUseCode")
I'm guessing I don't have the right combination of parentheses, double quotes, single quotes, etc. I've tried a number of different combinations without success. I'm sure my lack of experience is also in play here.
Any suggestions or advice how to resolve this issue would be greatly appreciated. Thanks for taking the time to review this question and for any help you can provide......

Answer 1

If you're asking about accessing nested values with a single call then maybe you can try something like this:
Sub tester()
Dim json As Object
Set json = JsonConverter.ParseJson(JsonContent)
Debug.Print JSONValue(json, "name") ' fred
Debug.Print JSONValue(json, "addresses/1/city") ' NYC
Debug.Print JSONValue(json, "addresses/2/street") ' Rue blah
Debug.Print JSONValue(json, "values/4") ' 40
End Sub
'return a "leaf" value from a `json` object
Public Function JSONValue(json As Object, MyField As String)
Dim res, arr, i, v
Set res = json
arr = Split(MyField, "/") 'array of keys/indexes
For i = LBound(arr) To UBound(arr)
v = arr(i)
If TypeName(res) = "Collection" Then v = CLng(v) 'numeric index for collection
If i <> UBound(arr) Then
'not at the end yet so have either a dictionary or a collection
Set res = res(v)
Else
'accessing a single non-object value
JSONValue = res(v)
End If
Next i
End Function
'dummy JSON content
Function JsonContent()
JsonContent = Replace("{'name':'fred','addresses':" & _
"[{'city':'NYC','street':'Easy St'}," & _
"{'city':'Paris','street':'Rue blah'}]," & _
"'values':[10,20,30,40]}", "'", """")
End Function
Very basic but should work if you just want a single non-object return value which might be nested several fields deep.