Develop Reference

Cleaning up nested if statements to be more readable?

I'm writing a project, and the part I'm doing now is getting arrow shaped real fast. How can I remove the nested if statements, but still have the same behaviour?
The code below might not look so bad now, but I'm planning on refactoring to include more methods.
public async Task FirstDiffTestAsync()
{
string folderDir = "../../../";
string correctReportDir = folderDir + "Reports To Compare/Testing - Copy.pdf";
string OptyNumber = "122906";
//Making a POST call to generate report
string result = ReportGeneration(OptyNumber).Result;
Response reportResponse = JsonConvert.DeserializeObject<Response>(result);
string newURL = reportResponse.documentUrl;
//Logging the Response to a text file for tracking purposes
await File.WriteAllTextAsync(Context.TestRunDirectory + "/REST_Response.txt", result);
using (StreamWriter w = File.AppendText(Context.TestDir + "/../log.txt"))
{
//Checking if the Integration failed
if (reportResponse.Error == null)
{
//now we have the url, reading in the pdf reports
List<string> Files = new List<string> { correctReportDir, newURL };
List<string> parsedText = PdfToParsedText(Files);
DiffPaneModel diff = InlineDiffBuilder.Diff(parsedText[0], parsedText[1]);
// DiffReport is a customised object
DiffReport diffReport = new DiffReport(correctReportDir, newURL);
diffReport.RunDiffReport(diff);
//In-test Logging
string indent = "\n - ";
string logMsg = $"{indent}Opty Number: {OptyNumber}{indent}Activity Number: {reportResponse.ActivityNumber}{indent}File Name: {reportResponse.FileName}";
if (diffReport.totalDiff != 0)
{
await File.WriteAllTextAsync(Context.TestRunDirectory + "/DiffReport.html", diffReport.htmlDiffHeader + diffReport.htmlDiffBody);
logMsg += $"{indent}Different lines: {diffReport.insertCounter} Inserted, {diffReport.deleteCounter} Deleted";
}
LogTesting(logMsg, w);
//Writing HTML report conditionally
if (diffReport.totalDiff != 0)
{
await File.WriteAllTextAsync(Context.TestRunDirectory + "/DiffReport.html", diffReport.htmlDiffHeader + diffReport.htmlDiffBody);
}
Assert.IsTrue(diffReport.insertCounter + diffReport.deleteCounter == 0);
}
else
{
LogTesting($" Integration Failed: {reportResponse.Error}", w);
Assert.IsNull(reportResponse.Error);
}
}
}

As mentioned in the comment, the indentation level is fine for now, but its always better to minimize when possible, especially when you are repeating same blocks of code.
The best way to do this is to write a separate function that contains that block of code and then call that function instead of the nested if statements.
In your case it would be something like this:
private async void checkTotalDiff(diffReport) {
...
}
You could pass anything you might need in the parameters. This way in your main code, you could replace the if statements with checkTotalDiff(diffReport) and save the return (if any) to a variable.
Also note I used void for return but you could change the type depending on what the function returns.

I wouldn't consider this as having an excessive amount of nested if-statements. It is fine as is. Otherwise you could do the following (also suggested by #Caius Jard):
public async Task FirstDiffTestAsync()
{
string folderDir = "../../../";
string correctReportDir = folderDir + "Reports To Compare/Testing - Copy.pdf";
string OptyNumber = "122906";
//Making a POST call to generate report
string result = ReportGeneration(OptyNumber).Result;
Response reportResponse = JsonConvert.DeserializeObject<Response>(result);
//Checking if the Integration failed
if (reportResponse.Error != null)
{
LogTesting($" Integration Failed: {reportResponse.Error}", w);
Assert.IsNull(reportResponse.Error);
return;
}
string newURL = reportResponse.documentUrl;
//Logging the Response to a text file for tracking purposes
await File.WriteAllTextAsync(Context.TestRunDirectory + "/REST_Response.txt", result);
using (StreamWriter w = File.AppendText(Context.TestDir + "/../log.txt"))
{
//now we have the url, reading in the pdf reports
List<string> Files = new List<string> { correctReportDir, newURL };
List<string> parsedText = PdfToParsedText(Files);
DiffPaneModel diff = InlineDiffBuilder.Diff(parsedText[0], parsedText[1]);
// DiffReport is a customised object
DiffReport diffReport = new DiffReport(correctReportDir, newURL);
diffReport.RunDiffReport(diff);
//In-test Logging
string indent = "\n - ";
string logMsg = $"{indent}Opty Number: {OptyNumber}{indent}Activity Number: {reportResponse.ActivityNumber}{indent}File Name: {reportResponse.FileName}";
if (diffReport.totalDiff != 0)
{
await File.WriteAllTextAsync(Context.TestRunDirectory + "/DiffReport.html", diffReport.htmlDiffHeader + diffReport.htmlDiffBody);
logMsg += $"{indent}Different lines: {diffReport.insertCounter} Inserted, {diffReport.deleteCounter} Deleted";
}
LogTesting(logMsg, w);
//Writing HTML report conditionally
if (diffReport.totalDiff != 0)
{
await File.WriteAllTextAsync(Context.TestRunDirectory + "/DiffReport.html", diffReport.htmlDiffHeader + diffReport.htmlDiffBody);
}
Assert.IsTrue(diffReport.insertCounter + diffReport.deleteCounter == 0);
}
}

C# Youtibe Video Title

I've been looking around and all of the answers I've found are either not C#, use the V2.0 API or use a method that doesn't return a valid result for videos with embedding disabled.
Here's what I'm currently using, from a response I found a while back:
public string GetYouTubeTitle(string url)
{
string id = GetArgs(url, "v", '?');
WebClient client = new WebClient();
return "YouTube Video: \"" + GetArgs(client.DownloadString("http://youtube.com/get_video_info?video_id=" + id), "title", '&') + "\"";
}
public string GetArgs(string args, string key, char query)
{
int iqs = args.IndexOf(query);
string querystring = null;
if (iqs != -1)
{
querystring = (iqs < args.Length - 1) ? args.Substring(iqs + 1) : string.Empty;
NameValueCollection nvcArgs = HttpUtility.ParseQueryString(querystring);
return nvcArgs[key];
}
return string.Empty;
}
It works perfectly the first time round, but the second video I tested returned the error: "&errorcode=150&reason=This+video+contains+content+from+Studio71_1_1.+It+is+restricted+from+playback+on+certain+sites"
My goal is just to get the title of a youtube video given the URL. But everything I'm seeing is either vague as hell or is only valid for the 2.0 API which doesn't even work anymore.
EDIT: And at some point I might want to add more to the response such as the length of the video. So I would prefer to have the API working than to just use something like get_video_info if possible.
EDIT:
For completeness and to help anyone who might be looking at this later on this is what I've got now that works like I want:
string titleurl = "https://www.googleapis.com/youtube/v3/videos?part=snippet&id=" + GetArgs(url, "v", '?') + "&key=" + apikey;
string timeurl = "https://www.googleapis.com/youtube/v3/videos?id=" + GetArgs(url, "v", '?') + "&part=contentDetails&key=" + apikey;
HttpWebRequest titlerequest = (HttpWebRequest)WebRequest.Create(titleurl);
HttpWebResponse titleresponse = (HttpWebResponse)titlerequest.GetResponse();
Stream titlestream = titleresponse.GetResponseStream();
StreamReader titlereader = new StreamReader(titlestream);
string titlejson = titlereader.ReadToEnd();
Newtonsoft.Json.Linq.JObject jObject = Newtonsoft.Json.Linq.JObject.Parse(titlejson);
string title = (string)jObject["items"][0]["snippet"]["title"];
HttpWebRequest timerequest = (HttpWebRequest)WebRequest.Create(timeurl);
HttpWebResponse timeresponse = (HttpWebResponse)timerequest.GetResponse();
Stream timestream = timeresponse.GetResponseStream();
StreamReader timereader = new StreamReader(timestream);
string timejson = timereader.ReadToEnd();
Newtonsoft.Json.Linq.JObject jObjectTime = Newtonsoft.Json.Linq.JObject.Parse(timejson);
string time = ParseTime((string)jObjectTime["items"][0]["contentDetails"]["duration"]);
if (title.Length > 0 && time.Length > 0 && time != "0")
return "YouTube Video: \"" + title + "\" (" + time + ")";
else return error; //error is a preset generic error string
It's probably not the cleanest code around, but it's doing what I want. So I don't really mind.

You can get the video title by using the YouTube Data API v3:
You need to get your API key from Here:
Make a GET request to this URL as described in the documentation:
https://www.googleapis.com/youtube/v3/videos?part=snippet&id=v2AC41dglnM,kTHNpusq654&key=YourAPIKeyHere
Parse the response you get with something like Json.NET:

try this:
First you need to install VideoLibrary on your visual studio package manager :
**Install-Package VideoLibrary**
using VideoLibrary;
Let's make a function to get the YouTube video title:
public string getTitle (string url){
YouTube ytb = YouTube.Default; //starting point for YouTube actions
var vid = ytb.GetVideo(url); // gets a Video object with info about the video
string ttl = vid.Title;//get video Title
return ttl;
}

Unauthoriezed Access Exception

i have a cloud database server like application on my computer that i'm hosting my game on. However, every time an user tries to save data i get an UnauthorizedAccessException.
Im running it by admin and i dont have any specias right in my folder so i have no idea what's the problem.
Here's my code:
public const string root = "D:/DATABASE/";
public static void WriteData(string playername, string type, string data)
{
if (!Directory.Exists("D:/DATABASE/" + playername))
{
Directory.CreateDirectory("D:/DATABASE/" + playername);
Directory.CreateDirectory("D:/DATABASE/" + playername + "/weapons");
}
if (type != "Weapon")
{
using (StreamWriter sw = new StreamWriter("D:/DATABASE/" + playername + "/" + type + ".sav"))
{
sw.WriteLine(data);
}
}
else
{
string[] dat = data.Split('%');
using (StreamWriter sw = new StreamWriter("D:/DATABASE/" + playername + "/weapons/" + dat[0] + ".gfa"))
{
string[] lines = dat[1].Split('#');
foreach (string cline in lines)
{
sw.WriteLine(cline);
}
}
}
}
public static string ReadLoadout(string playername)
{
string output = "";
string[] items = new string[2];
using (StreamReader sr = new StreamReader(root + playername + "/loadout.gfl"))
{
items[0] = sr.ReadLine();
items[1] = sr.ReadLine();
}
int c = 0;
foreach (string citem in items)
{
if (c > 0) output += "$";
output += citem + "%" + GetCompressedWeaponFile(playername, citem);
c++;
}
return output;
}
public static string GetCompressedWeaponFile(string playerName, string weaponName)
{
string output = "";
using (StreamReader sr = new StreamReader(root + playerName + "/weapons/" + weaponName))
{
string line = " ";
int c = 0;
while (line != null)
{
line = sr.ReadLine();
if (line != null)
{
if (c > 0) output += "#";
output += line;
}
c++;
}
}
return output;
}
public static void RegisterNewUser(string username, string password, string email)
{
string udir = root + username;
Directory.CreateDirectory(udir);
Directory.CreateDirectory(udir + "/weapons");
Directory.CreateDirectory(udir + "/loadouts");
File.WriteAllText(udir + "/password.sav", password);
File.WriteAllText(udir + "/level.sav", "1");
File.WriteAllText(udir + "/money.sav", "1000");
File.WriteAllText(udir + "/email.sav", email);
File.WriteAllText(udir + "/loadout.gfl", "");
using (StreamWriter sw = new StreamWriter(root + "emails.txt", true))
{
sw.WriteLine(email);
}
Email.Send(email, "New Account Registration", string.Format(mailTemplate, username, password));
}
public static void EditLoadout(string username, string items)
{
File.WriteAllLines(root + username + "/loadout.gfl",items.Split('#'));
}

It is difficult to provide specific help without more information. Here are a few of troubleshooting suggestions:
1) Try running your code on a different machine. Specifically your development computer. Do you still have the same error? If not, then there is indeed a permission problem.
2) Have you tried checking the stack trace of the exception?
When you run the application on your own computer, try using the IDE to display the exception. Yes, the problem may ultimately be in a low-level class, but you should be able to break on the error and go back in the call stack to see which method in your code is actually throwing the error.
3) Check the actual exception, even for a system-level exception.
Chances are, if you are able to debug this in the IDE, that you will see property information that will give you a hint. Is it in a directory method or a file write method? Check additional properties. Somewhere it might give you the text of the path (assuming it's a file issue) that it failed on that that could help narrow things down too.
4) Add Exception handling to your code
This is a good rule of thumb, and you should really do this anyway to make a stronger program. Regardless of who's method you are calling (yours, someone else's, or a system method) you need to determine where it should be handled.
For example, in your code, in the RegisterNewUser() method, consider something like:
public static void RegisterNewUser(string username, string password, string email)
{
try
{
string udir = root + username;
Directory.CreateDirectory(udir);
Directory.CreateDirectory(udir + "/weapons");
Directory.CreateDirectory(udir + "/loadouts");
File.WriteAllText(udir + "/password.sav", password);
File.WriteAllText(udir + "/level.sav", "1");
File.WriteAllText(udir + "/money.sav", "1000");
File.WriteAllText(udir + "/email.sav", email);
File.WriteAllText(udir + "/loadout.gfl", "");
using (StreamWriter sw = new StreamWriter(root + "emails.txt", true))
{
sw.WriteLine(email);
}
Email.Send(email, "New Account Registration", string.Format(mailTemplate, username, password));
}
catch (Exception ex)
{
// Create a method to display or log the exception, with it's own error handler
LogAndDisplayExceptions(ex);
// Send the user a message that we failed to add them. Put this in it's own try-catch block
// ideally, for readability, in it's own method.
try
{
Email.Send(email, "Failed to register", "An error occurred while trying to add your account.");
}
catch (Exception exNested)
{
LogAndDisplayExceptions(exNested);
}
}
}
5) Add a "crash-and-burn" exception handler to "main"
In the method that is your "top method" (it's hard to tell in the snippet you provided since there are few methods that would attempt to write to the disk) you could wrap your code in a try - catch block and print the exception or write it to disk.
If you have having trouble writing the exception to disk, I would suggest creating an error file first, make sure that the user account that is running the program can write to it, and then in the catch block open the file for APPEND. This should make it easier to get to the error text.
6) When all else fails, use the Debug class or Console class to write the traditional "I made it to line x."
While this will not solve your problem, it should help you get more information that will provide more insight into where your code is causing an error.

Getting "The process cannot access the file because it is being used by another process" when saving multiple files from the request stream

I am using the HTML5 canvas element and the new HTML5 file i\o function to drop multiple files on it and have them upload. It works fine, but now I need to generate a new filename if no files are in the destination directory (It's a 7 digit integer) or get the name of the last uploaded file, convert it to int32 and increment that by one for every new file being uploaded to the same directory. This is where the GetFileName(dir); comes in. The first image always uploads fine but the problem begins once the second file is saved and the process hits ImageJob.Build(), I presume this is because once the new file is starting to write, the GetFile() method runs for second file in line simultaneously and is checking for last written file, which is still being written and this creates the conflict. How can I fix this, maybe I can somehow itterate with a foreach over the Request.InputStream data or implement some kind process watch that waits for the process to finish?
Update: I tried using TempData to store the generated filename, and just increment on the int value in TempData for all the next file names and it appears to do better, gets more images in but still errors at some point. But TempData is not for that as it gets erased after each read, reassigning to it again does not help. Maybe I'll try storing it in session.
The process cannot access the file 'C:\Users\Admin\Documents\Visual Studio
2010\Projects\myproj\myproj\Content\photoAlbums\59\31\9337822.jpg'
because it is being used by another process.
public PartialViewResult Upload()
{
string fileName = Request.Headers["filename"];
string catid = Request.Headers["catid"];
string pageid = Request.Headers["pageid"];
string albumname = Request.Headers["albumname"];
var dir = "~/Content/photoAlbums/" + catid + "/" + pageid + "/" + (albumname ?? null);
var noex = GetFileName(dir);
var extension = ".jpg";
string thumbFile = noex + "_t" + extension;
fileName = noex + extension;
byte[] file = new byte[Request.ContentLength];
Request.InputStream.Read(file, 0, Request.ContentLength);
string imgdir;
string thumbimgdir;
string imageurl;
if (albumname != null)
{
imgdir = Server.MapPath("~/Content/photoAlbums/" + catid + "/" + pageid + "/" + albumname + "/" + fileName);
thumbimgdir = Server.MapPath("~/Content/photoAlbums/" + catid + "/" + pageid + "/" + albumname + "/" + thumbFile);
imageurl = "/Content/photoAlbums/" + catid + "/" + pageid + "/" + albumname + "/" + thumbFile;
}
else
{
imgdir = Server.MapPath("~/Content/photoAlbums/" + catid + "/" + pageid + "/" + fileName);
thumbimgdir = Server.MapPath("~/Content/photoAlbums/" + catid + "/" + pageid + "/" + thumbFile);
imageurl = "/Content/photoAlbums/" + catid + "/" + pageid + "/" + thumbFile;
}
ImageJob b = new ImageJob(file, imgdir, new ResizeSettings("maxwidth=1024&maxheight=768&format=jpg")); b.CreateParentDirectory = true; b.Build();
ImageJob a = new ImageJob(file, thumbimgdir, new ResizeSettings("w=100&h=100&mode=crop&format=jpg")); a.CreateParentDirectory = true; a.Build();
ViewBag.CatID = catid;
ViewBag.PageID = pageid;
ViewBag.FileName = fileName;
return PartialView("AlbumImage", imageurl);
}
public string GetFileName(string dir)
{
var FullPath = Server.MapPath(dir);
var dinfo = new DirectoryInfo(FullPath);
string FileName;
if (dinfo.Exists)
{
var Filex = dinfo.EnumerateFiles().OrderBy(x => x.Name).LastOrDefault();
FileName = Filex != null ? Path.GetFileNameWithoutExtension(Filex.Name) : null;
if (FileName != null)
{
FileName = FileName.Contains("_t") ? FileName.Substring(0, FileName.Length - 2) : FileName;
int fnum;
Int32.TryParse(FileName, out fnum);
FileName = (fnum + 1).ToString();
if (fnum > 999999) { return FileName; } //Check that TryParse produced valid int
else
{
var random = new Random();
FileName = random.Next(1000000, 9999000).ToString();
}
}
else
{
var random = new Random();
FileName = random.Next(1000000, 9999000).ToString();
}
}
else
{
var random = new Random();
FileName = random.Next(1000000, 9999000).ToString();
}
return FileName;
}

You simply cannot use the Random class if you want to generate unique filenames. It uses the current time as the seed, so two exactly concurrent requests will always produce the same 'random' number.
You could use a cryptographic random number generator,
but you would still have to ensure that (a) only one thread would generate it at a time, and (b) you used a sufficiently long identifier to prevent the Birthday paradox.
Thus, I suggest that everyone use GUID identifiers for their uploads, as they solve all of the above issues inherently (I believe an OS-level lock is used to prevent duplicates).
Your method also doesn't handle multiple file uploads per-request, although that may be intentional. You can support those by looping through Request.Files and passing each HttpPostedFile instance directly into the ImageJob.
Here's a simplified version of your code that uses GUIDs and won't encounter concurrency issues.
public PartialViewResult Upload()
{
string albumname = Request.Headers["albumname"];
string baseDir = "~/Content/photoAlbums/" + Request.Headers["catid"] + "/" + Request.Headers["pageid"] + "/" (albumname != null ? albumname + "/" : "");
byte[] file = new byte[Request.ContentLength];
Request.InputStream.Read(file, 0, Request.ContentLength);
ImageJob b = new ImageJob(file, baseDir + "<guid>.<ext>", new ResizeSettings("maxwidth=1024&maxheight=768&format=jpg")); b.CreateParentDirectory = true; b.Build();
ImageJob a = new ImageJob(file, baseDir + "<guid>_t.<ext>", new ResizeSettings("w=100&h=100&mode=crop&format=jpg")); a.CreateParentDirectory = true; a.Build();
//Want both the have the same GUID? Pull it from the previous job.
//string ext = PathUtils.GetExtension(b.FinalPath);
//ImageJob a = new ImageJob(file, PathUtils.RemoveExtension(a.FinalPath) + "_t." + ext, new ResizeSettings("w=100&h=100&mode=crop&format=jpg")); a.CreateParentDirectory = true; a.Build();
ViewBag.CatID = Request.Headers["catid"];
ViewBag.PageID = Request.Headers["pageid"];
ViewBag.FileName = Request.Headers["filename"];
return PartialView("AlbumImage", PathUtils.GuessVirtualPath(a.FinalPath));
}

If the process is relatively quick (small files) you could go in a loop, check for that exception, sleep the thread for a couple of seconds, and try again (up to a maximum number of iterations). One caveat is that if the upload is asynchronous you might miss a file.
A couple of other suggestions:
Make the GetFileName to be a private method so that it doesn't get triggered from the web.
The OrderBy in the Filex query might not do what you expect once the it goes to 8 digits (possible if the first Random() is a very high number).
The Random() should probably be seeded to produce better randomness.

Payment succeeds, and our data matches querystring data, but falls thru to INVALID anyway!

Why does my ipn script I wrote always fail? It always goes to INVALID even though it matches everything in the query string that paypal sends to me?
notification.cshtml?tx=b78v54b5b55rby92S&st=Completed&amt=3.04&cc=USD&cm=&item_number=&merchant_return_link=Return+to+web+site+name&form_charset=UTF-8
And the part that checks it is:
string LiveURL = "https://www.paypal.com/cgi-bin/webscr";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(LiveURL);
// Set request back values.
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
byte[] parameters = Request.BinaryRead(HttpContext.Current.Request.ContentLength);
string RequestString = System.Text.Encoding.ASCII.GetString(parameters);
RequestString += "&cmd=_notify-validate";
request.ContentLength = RequestString.Length;
// Send request to PP and get response.
StreamWriter Sout = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
Sout.Write(RequestString);
Sout.Close();
StreamReader Sin = new StreamReader(request.GetResponse().GetResponseStream());
string response = Sin.ReadToEnd();
Sin.Close();
if(result != null && result.OrderStatus == "Confirmed")
{
switch(response)
{
case "VERIFIED":
if(Request["st"] == "Completed")
{
var PPQuery = "SELECT TransactionId, OrderTotal FROM Orders WHERE OrderId = '" + Session["OSFOID"] + "' AND UserId = '" + WebSecurity.CurrentUserId + "'";
var ppQueryResult = database.Query(PPQuery);
foreach(var item in ppQueryResult)
{
decimal fff = 3.04M;
if(item["TransactionId"] != Request["tx"])
{
if(item["OrderTotal"] == TotalPrice)
{
// Payment was a success. Convey that to the user.
output = "Thanks. Order complete.";
}
else
{
// Possible fraud. Log it.
}
}
else
{
// This is a duplicate transaction. Log it and Redirect to homepage.
}
}
}
break;
case "INVALID":
output = "Invalid was returned. Investigate further.";
break;
default:
output = "Other exception has occured. Investigate further and log.";
break;
}
}

The code looks fine. The problem must be with response not matching "VERIFIED".
You're not in Turkey by chance, and changing response to uppercase prior to the comparison? *
*) If the locale is Turkey, uppercasing a string turns i into İ, not I (just one of the many traps with string manipulation)

Within the "VERIFIED" block, check:
if (Request.Params["payment_status"] == "Completed")
{
...
}
Request["st"] is incorrect.
Be sure to set IPN URL in one place in PayPal admin and do not use the other form of return URL checking (can't remember the name of it offhand) and IPN at the same time.
There is no "merchant_return_link" parameter; I think it should be "notify_url"... the URL string and the list of params doesn't look right to me; for example: &cm=&item_number
I know your list of params will be unique for your situation, but here's some sample code where I construct the URL to be passed to PayPal:
protected string GetPayPalURL(string SERVER_URL, string business, string[] itemNames,
int[] quantities, decimal[] amounts, double[] weight, string invoiceID, string transID, string NOTIFY_URL)
{
// Customer will be required to specify delivery address to PayPal - VERY IMPORTANT
const string NO_SHIPPING = "2";
StringBuilder url = new StringBuilder();
url.Append(SERVER_URL + "?cmd=_cart&upload=1");
url.Append("&business=" + HttpUtility.UrlEncode(business));
for (int i = 0; i < itemNames.Length; i++)
{
url.Append("&item_name" + "_" + (i + 1).ToString() + "=" + HttpUtility.UrlEncode(itemNames[i]));
url.Append("&quantity" + "_" + (i + 1).ToString() + "=" + quantities[i].ToString().Replace(",", "."));
url.Append("&amount" + "_" + (i + 1).ToString() + "=" + amounts[i].ToString().Replace(",", "."));
url.Append("&weight" + "_" + (i + 1).ToString() + "=" + weight[i].ToString().Replace(",", "."));
}
url.Append("&no_shipping=" + HttpUtility.UrlEncode(NO_SHIPPING));
url.Append("&custom=" + HttpUtility.UrlEncode(invoiceID));
url.Append("&txn_id=" + HttpUtility.UrlEncode(transID));
url.Append("&notify_url=" + HttpUtility.UrlEncode(NOTIFY_URL));
return url.ToString();
}

I think the Paypal method you are trying to do is as follows on code project
and if you get payment_status = INVALID, then check the reason in payment_reason

i dont see in the code where you are defining result which is checked in the if, also in the switch you are checking against request, surely this should be against response?