[RESOLVED] HttpWebRequest: POST to HttpContext 'Form' collection

[SJWhiteley]

I'm struggling to pass data through an HttpWebRequest object in a Windows application to show up as Form variables in the HttpContext.Request.Form collection on an ASP.NET server in a generic ASHX handler.

Windows app posting code:

Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
	' POST
	Dim sendString As String = "{""coilid""=""Ax1223""}"
	Dim wr As Net.HttpWebRequest = CType(Net.HttpWebRequest.Create("http://10.20.120.36/ajax/coilbucket.ashx"), Net.HttpWebRequest)
	wr.KeepAlive = False
	wr.Method = "POST"
	wr.ContentType = "application/json; charset=utf-8;"
	Using sw As IO.StreamWriter = New IO.StreamWriter(wr.GetRequestStream)
		sw.Write(sendString)
	End Using
	' READ RESPONSE
	Dim res As Net.WebResponse = wr.GetResponse()
	Dim str As New IO.StreamReader(res.GetResponseStream, System.Text.Encoding.UTF8)
	Dim s As String = str.ReadToEnd()
	Debug.WriteLine(s)
End Sub

The code, above, formats the POST as a JSON object, which it appears to do correctly, but am unable to read the request in neither the Form collection or the queryString collection of the HttpContext.Request object.

The ASP.NET code:

Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
	Dim d As New Dictionary(Of String, Object)(StringComparer.OrdinalIgnoreCase)
	'
	Dim sb As New System.Text.StringBuilder
	For Each s As String In context.Request.Form
		If sb.Length > 0 Then sb.Append(",")
		sb.Append(s & "=" & context.Request.Form.Item(s))
	Next
	d.Item("forms") = sb.ToString
	sb.Clear()
	For Each s As String In context.Request.QueryString
		If sb.Length > 0 Then sb.Append(",")
		sb.Append(s & "=" & context.Request.QueryString.Item(s))
	Next
	d.Item("querystring") = sb.ToString
	' This function simply converts a dictionary to a JSON string
	Dim result As String = App.JSONString(d)
	'
	' - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	context.Response.ContentType = "text/plain"
	context.Response.Write(result)
	' - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
End Sub

The result is:

{"forms":"","querystring":""}

When performing the same POST from JQuery, the Forms collection is populated:

{"forms":"coilid=254879","querystring":""}

(Understandably, the QueryString is not populated - I can do that by adding a query string to the URI).

JQuery AJAX Call:

$.ajax({
	url: '/ajax/coilbucket.ashx',
	type: 'POST',
	dataType: 'json',
	data: { coilid: id },
	beforeSend: function () {
		...
	},
	success: function (data, textStatus, xhr) {
		...
	},
	error: function (xhr, textStatus, errorThrown) {
		...
	}
});

So, how do I get the POST data as a JSON representation to show up in the Forms collection from a windows application just like the JQuery AJAX call?

EDIT: SOLVED.

The JQuery .ajax() properties were setup incorrectly - the contentType was not specifically set, so was default (x-www-form-urlencoded) which, while worked, was not the understood behavior. The data populated the forms collection. By sending the data as 'application/json' as the content type from the windows application AND the JQuery ajax call, neither the forms collection or the queryString are populated. The JSON string must be parsed through context.Request.InputStream.

With 'x-www-form-urlencoded', the Form collection is populated, but the posted data must be of a url encoded string, and not JSON. I actually had a mistake in my .ajax() call which gave me what I wanted - a 'bug which worked' - but was only brought to light when accessing the handler from a .NET windows application.

I don't know if anyone understood this problem, but I got it figured out, so it's here for posterity.