Get Classic ASP variable from posted JSON

Question

I'm trying to post JSON via AJAX to a Classic ASP page, which retrieves the value, checks a database and returns JSON to the original page.

I can post JSON via AJAX

I can return JSON from ASP

I can't retrieve the posted JSON into an ASP variable

POST you use Request.Form, GET you use Request.Querystring......... what do I use for JSON?

I have JSON libraries but they only show creating a string in the ASP script and then parsing that. I need to parse JSON from when being passed an external variable.

Javascipt

var thing = $(this).val();

$.ajax({
         type: "POST",
         url: '/ajax/check_username.asp',
          data: "{'userName':'" + thing + "'}",
          contentType: "application/json; charset=utf-8",
          dataType: "json",
         cache: false,
      async: false,
         success: function() {
alert('success');
      });

ASP file (check_username.asp)

    Response.ContentType = "application/json"
          sEmail = request.form() -- THE PROBLEM

          Set oRS = Server.CreateObject("ADODB.Recordset")
          SQL = "SELECT SYSUserID FROM dbo.t_SYS_User WHERE Username='"&sEmail&"'" 
          oRS.Open SQL, oConn
          if not oRS.EOF then 
            sStatus = (new JSON).toJSON("username", true, false)
          else
            sStatus = (new JSON).toJSON("username", false, false)
        end if
response.write sStatus

Answer 1

You can find all posted parameters via this code.

FUNCTION getQueryString()
    dim queryLink, queryItemName
    queryLink = ""
    On error Resume Next
    For each queryItemName in Request.QueryString
        Execute(queryItemName & " = stripQuery(Request.QueryString(""" & queryItemName & """))")
        queryLink = queryLink & "&" & queryItemName & "=" & Request.QueryString(queryItemName)
    Next
    For each queryItemName in Request.Form
        Execute(queryItemName & " = stripQuery(Request.Form(""" & queryItemName & """))")
        queryLink = queryLink & "&" & queryItemName & "=" & Request.Form(queryItemName)
    Next
    On Error Goto 0
    getQueryString = queryLink
END FUNCTION

response.write getQueryString()

Answer 2

You may consider switching from VBScript to JScript (JScript is what microsoft calls JavaScript).

Why? Because then from within Classic ASP you can do the same JSON calls that the browser can do and read the results into JavaScript objects using the eval() statement.

Paddy Said: I don't have an answer, but you have my every sympathy... classic asp and JSON handling - sounds like fun.

@Paddy: Classic ASP and JSON IS fun, in fact it ROCKS! (If you switch from VBScript and use JScript.)

Note that you don't have to quit VBScript cold-turkey, you can still interoperate between the two in the same ASP file but if you declare JScript first you need to confine your VBScript to SUB or functions and vice-versa otherwise unpredictable things can happen.

Here's a quick example of what I'm talking about:

<%@ LANGUAGE="JScript" %>
<%

var days = VBDateDiff("d", "4/10/2010", "5/3/2010");
Response.write("JScript Calling VBScript function: days = " + days);


%> <script language="VBScript" runat="server">
function VBDateDiff(units, datebefore, dateafter)
    VBDateDiff = CStr(DateDiff(units, datebefore, dateafter))
end function

function VBDateAdd(units, nUnits, theDate)
    Response.write("<BR>VBDateAdd units=" & units & ", nUnits=" & nUnits & ", theDate=" & theDate)
    VBDateAdd = CStr(DateAdd(units, nUnits, theDate))
    Response.write(", VBDateAdd=" & VBDateAdd)
end function
</script> <%        

%>  

Answer 3

I having same issue but very soon i figure out how to post a json object to ASP server.

Here is the idea: not tested. Work hard on it ><.

Parse the json object into string then post back to server.(this is a typical string posting)

on ASP side, use JSON library to parse the string back into the object.

link for the JSON library http://code.google.com/p/aspjson/

'I assume ppl that try post JSON back to asp should have basic posting knowledge. Any further assistance please let me know

Answer 4

Generally (new VBArray(arr).toArray()) should work on a SafeArray, which is what Request.BinaryRead returns. But it doesn't. I found this solution which I revised:

function GetRawRequestData() {
    var byteCount = Request.TotalBytes;
    var binary = Request.BinaryRead(byteCount)
    var reader = Server.CreateObject('ADODB.Recordset');
    reader.Fields.Append('x', 201, byteCount);
    reader.Open();
    reader.AddNew();
    reader.Fields(0).AppendChunk(binary);
    reader.update();
    return reader.Fields(0).Value;
}

thanks to Rasberry's comment @ http://blogs.msdn.com/b/david.wang/archive/2006/07/04/howto-convert-between-jscript-array-and-vb-safe-array.aspx

Note that it might not handle encoding correctly. I didn't dive into what 201 for ADO datatype means, but it works.