JSON import to Excel

Question

Is it possible to script JSON calls in a macro?

I want to get a JSON string through an API connection. It looks like the problem is Excel expects the parameters to be passed in the HTML-string, but JSON passes parameters in the HTML body. Any ideas?

Answer 1

Since this is VBA, I'd use COM to call xmlhttprequest but use it in synchronous manner as not to upset VBA’s single threaded execution environment, A sample class that illustrates a post and get request in this manner follows:

'BEGIN CLASS syncWebRequest  Private Const REQUEST_COMPLETE = 4  Private m_xmlhttp As Object Private m_response As String  Private Sub Class_Initialize()     Set m_xmlhttp = CreateObject("Microsoft.XMLHTTP") End Sub  Private Sub Class_Terminate()     Set m_xmlhttp = Nothing End Sub   Property Get Response() As String     Response = m_response End Property  Property Get Status() As Long     Status = m_xmlhttp.Status End Property  Public Sub AjaxPost(Url As String, Optional postData As String = "")     m_xmlhttp.Open "POST", Url, False     m_xmlhttp.setRequestHeader "Content-type", "application/x-www-form-urlencoded"     m_xmlhttp.setRequestHeader "Content-length", Len(postData)     m_xmlhttp.setRequestHeader "Connection", "close"     m_xmlhttp.send (postData)     If m_xmlhttp.readyState = REQUEST_COMPLETE Then         m_response = m_xmlhttp.responseText     End If End Sub  Public Sub AjaxGet(Url As String)     m_xmlhttp.Open "GET", Url, False     m_xmlhttp.setRequestHeader "Connection", "close"     m_xmlhttp.send     If m_xmlhttp.readyState = REQUEST_COMPLETE Then         m_response = m_xmlhttp.responseText     End If End Sub  'END CLASS syncWebRequest    

So now you can call the above to return you the server's response:

Dim request As New syncWebRequest request.ajaxGet "http://localhost/ClientDB/AllClients?format=json"  Dim json as string  json = request.Response 

The problem here is we want to be able to read the data returned from the server in some way, more so than manipulating the JSON string directly. What's worked for me is using the VBA-JSON (google code export here) COM type Collection to handle JSON arrays and Dictionary to handle members and their declarations, with a parser factory method Parse that basically makes creating these collections of dictionaries much simpler.

So now we can parse the JSON:

[{"Name":"test name","Surname":"test surname","Address":{"Street":"test street","Suburb":"test suburb","City":"test city"}}] 

into something like the following:

Set clients = parser.parse(request.Response) For Each client In clients     name = client("Name")     surname = client("Surname")     street = client("Address")("Street")     suburb = client("Address")("Suburb")     city = client("Address")("City") Next 

That's nice but what about stuff like being able to edit and post back the data? Well there's also a method toString to create a JSON string from the above [Collection/Dictionary] JSON data, assuming the server accepts JSON back.