c# - Why is the value null when using session variable -

c# - Why is the value null when using session variable -

i have asp.net website located in 1 of server , accessing site local pc on same network. when application runs, saves pdf file in c:\pdffolder folder. want display link user can download file in local pc server.

i using session variable filename:

string strfilename = "completed_pdf_" + k + ".pdf"; //k variable within function session["filename"] = strfilename;

in server folder files stored is: c:\pdffolder\{filename}.pdf local pc access file is: \\myserver\pdffolder\{filename}.pdf

the code download button is:

protected void downloadfile(object sender, eventargs e) { //messagebox.show(session["pathname"].tostring()); //messagebox.show(session["filename"].tostring()); messagebox.show(path.combine(@"c:\pdfgenerate", session["filename"].tostring()).tostring()); response.redirect("downloadfilepdf.ashx?myvar=" + session["filename"].tostring()); }

on button download file, fire httphandler function onclick:

<%@ webhandler language="c#" class="downloadfilepdf" %> using system; using system.web; using system.io; public class downloadfilepdf : ihttphandler { public void processrequest (httpcontext context) { system.web.httprequest request2 = system.web.httpcontext.current.request; string strsessvar2 = request2.querystring["filename"]; system.web.httpresponse response = system.web.httpcontext.current.response; response.clearcontent(); response.clear(); response.contenttype = "application/pdf"; byte[] filebytearray = file.readallbytes(path.combine(@"c:\pdfgenerate", strsessvar2)); response.addheader("content-disposition", string.format("attachment; filename={0}.pdf", strsessvar2)); response.binarywrite(filebytearray); response.end(); } public bool isreusable { { homecoming false; } } }

i maintain getting error on line: byte[] filebytearray = file.readallbytes(path.combine(@"c:\pdfgenerate", strsessvar2));

the error is: value cannot null

how can prepare issue?

i believe issue line:

string strsessvar2 = request2.querystring["filename"];

you want value of myvar:

string strsessvar2 = request2.querystring["myvar"];

c# asp.net pdf