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Excel VBA macro using iTunes search API – fastest way to query & parse JSON results

Posted by: admin May 14, 2020 Leave a comment

Questions:

I am trying to build Excel page from iTunes query data.
An example for Angry Birds app my query would look like:
https://itunes.apple.com/lookup?id=343200656&country=AL checking Albania iTunes
https://itunes.apple.com/lookup?id=343200656&country=DZ checking Algeria iTunes
… 150 more stores

My question is the most efficient way to do this query and parse response.
I only know how to to xmlhttp query. Please enlighten me as the better way to do this.
I have read some documentation for VB-JSON, Json.net, CDataSet, fastJSON, but cannot figure out how to get started trying those tools. Anyone have more VBA code examples pulling JSON or way to explain usage of these frameworks to a newb?

Dim innerHTML As Object
Dim myText As String
JsonCheck = ""
Set innerHTML = CreateObject("Microsoft.XMLHTTP")
With innerHTML
    .Open "GET", iTunesAPI_link, False
    .send
    myText = .responsetext
End With
Set innerHTML = Nothing
If InStr(myText, ":0") = 20 Then   'no results found
    result = "Down"
ElseIf InStr(myText, "Your request produced an error.") = 46 Then 'link error
    result = HTMLCheck(human iTunes link)
Else      'found the app
    result = call function which parses myText for desired fields
Endif
How to&Answers:

Here’s a basic approach using the scriptcontrol:

Sub Tester()

    Dim json As String
    Dim sc As Object
    Dim o

    Set sc = CreateObject("scriptcontrol")
    sc.Language = "JScript"

    json = HttpGet("https://itunes.apple.com/lookup?id=343200656&country=AL")

    'some json property names may be keywords in VBA, so replace with
    '  something similar....
    json = Replace(json, """description""", """description_r""")
    Debug.Print json

    sc.Eval "var obj=(" & json & ")" 'evaluate the json response
    'add some accessor functions
    sc.AddCode "function getResultCount(){return obj.resultCount;}"
    sc.AddCode "function getResult(i){return obj.results[i];}"

    Debug.Print sc.Run("getResultCount")

    Set o = sc.Run("getResult", 0)
    Debug.Print o.kind, o.features, o.description_r

End Sub

Function HttpGet(url As String) As String
    Dim oHTML As Object
    Set oHTML = CreateObject("Microsoft.XMLHTTP")
    With oHTML
        .Open "GET", url, False
        .send
        HttpGet = .responsetext
    End With
End Function

There’s a worked-out approach in Codo’s answer to this question: Excel VBA: Parsed JSON Object Loop

Answer:

I had a similar issue with querying Salesforce’s REST API and found dealing with JSON through ScriptControl ended up being unmanageable. I used the following library for parsing and converting to JSON and it’s worked perfectly for me: https://code.google.com/p/vba-json/.

Dim JSON As New JSONLib
Dim Parsed As Object

Set Parsed = JSON.parse(jsonValue)
Debug.Print Parsed("resultCount")
Debug.Print Parsed("results")(0)

Using that library, I then wrapped up some of the common functionality for making web requests that I think would help you out: https://github.com/timhall/Excel-REST

Using these libraries, your code would look something like the following:

Dim iTunesClient As New RestClient
iTunesClient.BaseUrl = "https://itunes.apple.com/"

Dim Request As New RestRequest
Request.Format = json
Request.Resource = "lookup"
Request.AddQuerystringParam "id", "343200656"
Request.AddQuerystringParam "country", "AL"

Dim Response As RestResponse
Set Response = iTunesClient.Execute(Request)

' => GET https://itunes.apple.com/lookup?id=343200656&country=AL

If Response.StatusCode = 200 Then
    ' Response.Data contains converted JSON Dictionary/Collection
    Debug.Print "Result Count: " & Response.Data("resultCount")
    Dim i As Integer
    For i = LBound(Response.Data("results")) To UBound(Response.Data("results"))
        Debug.Print "Result " & i & ": " & Response.Data("results")(i)
    Next i
Else
    Debug.Print "Error: " & Response.Content
End If