Develop Reference

Get Last two folder's name from URL using C#

I have a URL and from which i need to get names after "bussiness" and Before the Page Name i.e. "paradise-villas-little.aspx" from below URL.
http://test.com/anc/bussiness/accommo/resort/paradise-villas-little.aspx
I am not getting how can i get this. i have tried the RawUrl, but it fetched the full. Please help me how can i do this.
UPDATE: This is a type of URL, i need to check it for dynamically.

You can create a little helper, and parse the URL from it's Uri Segments :
public static class Helper
{
public static IEnumerable<String> ExtractSegments(this Uri uri, String exclusiveStart)
{
bool startFound = false;
foreach (var seg in uri.Segments.Select(i => i.Replace(#"/","")))
{
if (startFound == false)
{
if (seg == exclusiveStart)
startFound = true;
}
else
{
if (!seg.Contains("."))
yield return seg;
}
}
}
}
And call it like this :
Uri uri = new Uri(#"http://test.com/anc/bussiness/accommo/resort/paradise-villas-little.aspx");
var found = uri.ExtractSegments("bussiness").ToList();
Then found contains "accommo" and "resort", and this method is extensible to any URL length, with or without file name at the end.

Nothing sophisticated in this implementation, just regular string operations:
string url = "http://test.com/anc/bussiness/accommo/resort/paradise-villas-little.aspx";
string startAfter = "business";
string pageName = "paradise-villas-little.aspx";
char delimiter = '/'; //not platform specific
var from = url.IndexOf(startAfter) + startAfter.Length + 1;
var to = url.Length - from - pageName.Length - 1;
var strings = url.Substring(from, to).Split(delimiter);
You may want to add validations though.

You have to use built-in string methods. The best is to use String Split.
String url = "http://test.com/anc/bussiness/accommo/resort/paradise-villas-little.aspx";
String[] url_parts = url.Split('/'); //Now you have all the parts of the URL all folders and page. Access the folder names from string array.
Hope this helps

ClrZmq returning messages always to first started client

We're creating a WPF app in which we execute python scripts from different Test Stations and show the output in its corresponding output panel, To run the scripts in parallel we are using Task but when we run the scripts in parallel from the stations, We are getting the output of other stations also into the station that is started first, we're using the following code,
private void ZmqStatusListener(string endPoint)
{
using (Context context = new Context())
{
StatusPort = string.Empty;
TestResultPort = string.Empty;
using (Socket server = context.Socket(SocketType.REP))
{
try
{
if (isStatusContextActive == false || isPortChanged == true)
{
server.Bind(endPoint);
isStatusContextActive = true;
}
}
catch (ZMQ.Exception ex)
{
if (ex.Errno != 100)
{
string IPCPort = _globalParameters.GlbParam.GlbParamIpcStartPort;
if (IPCPort == string.Empty)
{
IPCPort = "0";
}
if (endPoint == EditorConstants.PortAddress.PortPrefix + IPCPort)
{
StatusPort = endPoint;
TestReultError = EditorConstants.CommonMessageTypes.TestReultError + ex.Message + EditorConstants.CommonMessageTypes.StackTraceMessage + ex.StackTrace;
}
StopExecOfScript(default(object));
isCancelledtask = true;
ScriptStatusDesc = new ScriptStatusDesc()
{
Status = "Failed",
statusDescription = "Failed"
};
}
}
while (true)
{
string message = server.Recv(Encoding.UTF8);
UpdateTestResults(message);
server.Send(" ACK", Encoding.UTF8);
// if (message == "Test Passed")
//break;
}
}
}
}
and for testing purpose we're breaking the while loop in this code based on a test message we kept in the python script, then we are able to get the output in the respective station correctly but this way we can only run in a synchronous fashion which we don't want as we require to run the test stations in parallel and the while loop should not break as it should be listening for the response.

We were able to solve the issue by getting clues doing a sample app to reproduce the issue and to first know whether our ClrZmq pattern was correct for us or not and it is correct. The resolution we followed is that when we needed to bind that data to its corresponding View's Model object in its ViewModel so had to retrieve View's DataContext which is of Type ISomeXViewModel for the particular TestStation using an Id of that TestStation we did this cos all of our TestStations are dynamically added and we even store it to be accessed wherever necessary. This issue was caused to due multiple instances of UserControls so we explicitly needed to update the TestStation manually with a little more effort.
Sample Code Snippet
private void BindTestResult(string xmlPayLoad)
{
// converting xmlPalLoad to a class/model object
ITestStationViewModel viewModel = (ITestStationViewModel)((IView)DynamicTestStationsGrid.Children[StationNumber].Content).DataContext;
// IView class has DataContext property so I am type casting the Content which is ContentControl to IView type first and later to ITestStationViewModel
viewModel.TestStationModel = xmlPayLoadModel;
}
Thanks.

How to refer to an identifier without writing it into a string literal in C#?

I often want to do this:
public void Foo(Bar arg)
{
throw new ArgumentException("Argument is incompatible with " + name(Foo));
}
Because if I change the name of Foo the IDE will refactor my error message too, what won't happen if I put the name of the method (or any other kind of member identifier) inside a string literal. The only way I know of implementing "name" is by using reflection, but I think the performance loss outweighs the mantainability gain and it won't cover all kinds of identifiers.
The value of the expression between parenthesis could be computed at compile time (like typeof) and optimized to become one string literal by changing the language specification. Do you think this is a worthy feature?
PS: The first example made it look like the question is related only to exceptions, but it is not. Think of every situation you may want to reference a type member identifier. You'll have to do it through a string literal, right?
Another example:
[RuntimeAcessibleDocumentation(Description="The class " + name(Baz) +
" does its job. See method " + name(DoItsJob) + " for more info.")]
public class Baz
{
[RuntimeAcessibleDocumentation(Description="This method will just pretend " +
"doing its job if the argument " + name(DoItsJob.Arguments.justPretend) +
" is true.")]
public void DoItsJob(bool justPretend)
{
if (justPretend)
Logger.log(name(justPretend) + "was true. Nothing done.");
}
}
UPDATE: this question was posted before C# 6, but may still be relevant for those who are using previous versions of the language. If you are using C# 6 check out the nameof operator, which does pretty much the same thing as the name operator in the examples above.

well, you could cheat and use something like:
public static string CallerName([CallerMemberName]string callerName = null)
{
return callerName;
}
and:
public void Foo(Bar arg)
{
throw new ArgumentException("Argument is incompatible with " + CallerName());
}
Here, all the work is done by the compiler (at compile-time), so if you rename the method it will immediately return the correct thing.

If you simply want the current method name: MethodBase.GetCurrentMethod().Name
If it's a type typeof(Foo).Name
If you want the name of a variable/parameter/field/property, with a little Expression tree
public static string GetFieldName<T>(Expression<Func<T>> exp)
{
var body = exp.Body as MemberExpression;
if (body == null)
{
throw new ArgumentException();
}
return body.Member.Name;
}
string str = "Hello World";
string variableName = GetFieldName(() => str);
For method names it's a little more tricky:
public static readonly MethodInfo CreateDelegate = typeof(Delegate).GetMethod("CreateDelegate", BindingFlags.Static | BindingFlags.Public, null, new[] { typeof(Type), typeof(object), typeof(MethodInfo) }, null);
public static string GetMethodName<T>(Expression<Func<T>> exp)
{
var body = exp.Body as UnaryExpression;
if (body == null || body.NodeType != ExpressionType.Convert)
{
throw new ArgumentException();
}
var call = body.Operand as MethodCallExpression;
if (call == null)
{
throw new ArgumentException();
}
if (call.Method != CreateDelegate)
{
throw new ArgumentException();
}
var method = call.Arguments[2] as ConstantExpression;
if (method == null)
{
throw new ArgumentException();
}
MethodInfo method2 = (MethodInfo)method.Value;
return method2.Name;
}
and when you call them you have to specify the type of a compatible delegate (Action, Action<...>, Func<...> ...)
string str5 = GetMethodName<Action>(() => Main);
string str6 = GetMethodName<Func<int>>(() => Method1);
string str7 = GetMethodName<Func<int, int>>(() => Method2);
or more simply, without using expressions :-)
public static string GetMethodName(Delegate del)
{
return del.Method.Name;
}
string str8 = GetMethodName((Action)Main);
string str9 = GetMethodName((Func<int>)Method1);
string str10 = GetMethodName((Func<int, int>)Method2);

As has been covered, using this approach for exceptions seems unnecessary due to the method name being in the call stack on the exception.
In relation to the other example in the question of logging the parameter value, it seems PostSharp would be a good candidate here, and probably would allow lots of new features of this kind that you're interested in.
Have a look at this page on PostSharp which came up when I searched for how to use PostSharp to log parameter values (which it covers). An excerpt taken from that page:
You can get a lot of useful information with an aspect, but there are three popular categories:
Code information: function name, class name, parameter values, etc. This can help you to reduce guessing in pinning down logic flaws or edge-case scenarios
Performance information: keep track of how much time a method is taking
Exceptions: catch select/all exceptions and log information about them

The original question is named "How to refer to an identifier without writing it into a string literal in C#?" This answer does not answer that question, instead, it answers the question "How to refer to an identifier by writing its name into a string literal using a preprocessor?"
Here is a very simple "proof of concept" C# preprocessor program:
using System;
using System.IO;
namespace StackOverflowPreprocessor
{
/// <summary>
/// This is a C# preprocessor program to demonstrate how you can use a preprocessor to modify the
/// C# source code in a program so it gets self-referential strings placed in it.
/// </summary>
public class PreprocessorProgram
{
/// <summary>
/// The Main() method is where it all starts, of course.
/// </summary>
/// <param name="args">must be one argument, the full name of the .csproj file</param>
/// <returns>0 = OK, 1 = error (error message has been written to console)</returns>
static int Main(string[] args)
{
try
{
// Check the argument
if (args.Length != 1)
{
DisplayError("There must be exactly one argument.");
return 1;
}
// Check the .csproj file exists
if (!File.Exists(args[0]))
{
DisplayError("File '" + args[0] + "' does not exist.");
return 1;
}
// Loop to process each C# source file in same folder as .csproj file. Alternative
// technique (used in my real preprocessor program) is to read the .csproj file as an
// XML document and process the <Compile> elements.
DirectoryInfo directoryInfo = new DirectoryInfo(Path.GetDirectoryName(args[0]));
foreach (FileInfo fileInfo in directoryInfo.GetFiles("*.cs"))
{
if (!ProcessOneFile(fileInfo.FullName))
return 1;
}
}
catch (Exception e)
{
DisplayError("Exception while processing .csproj file '" + args[0] + "'.", e);
return 1;
}
Console.WriteLine("Preprocessor normal completion.");
return 0; // All OK
}
/// <summary>
/// Method to do very simple preprocessing of a single C# source file. This is just "proof of
/// concept" - in my real preprocessor program I use regex and test for many different things
/// that I recognize and process in one way or another.
/// </summary>
private static bool ProcessOneFile(string fileName)
{
bool fileModified = false;
string lastMethodName = "*unknown*";
int i = -1, j = -1;
try
{
string[] sourceLines = File.ReadAllLines(fileName);
for (int lineNumber = 0; lineNumber < sourceLines.Length - 1; lineNumber++)
{
string sourceLine = sourceLines[lineNumber];
if (sourceLine.Trim() == "//?GrabMethodName")
{
string nextLine = sourceLines[++lineNumber];
j = nextLine.IndexOf('(');
if (j != -1)
i = nextLine.LastIndexOf(' ', j);
if (j != -1 && i != -1 && i < j)
lastMethodName = nextLine.Substring(i + 1, j - i - 1);
else
{
DisplayError("Unable to find method name in line " + (lineNumber + 1) +
" of file '" + fileName + "'.");
return false;
}
}
else if (sourceLine.Trim() == "//?DumpNameInStringAssignment")
{
string nextLine = sourceLines[++lineNumber];
i = nextLine.IndexOf('\"');
if (i != -1 && i != nextLine.Length - 1)
{
j = nextLine.LastIndexOf('\"');
if (i != j)
{
sourceLines[lineNumber] =
nextLine.Remove(i + 1) + lastMethodName + nextLine.Substring(j);
fileModified = true;
}
}
}
}
if (fileModified)
File.WriteAllLines(fileName, sourceLines);
}
catch (Exception e)
{
DisplayError("Exception while processing C# file '" + fileName + "'.", e);
return false;
}
return true;
}
/// <summary>
/// Method to display an error message on the console.
/// </summary>
private static void DisplayError(string errorText)
{
Console.WriteLine("Preprocessor: " + errorText);
}
/// <summary>
/// Method to display an error message on the console.
/// </summary>
internal static void DisplayError(string errorText, Exception exceptionObject)
{
Console.WriteLine("Preprocessor: " + errorText + " - " + exceptionObject.Message);
}
}
}
And here's a test file, based on the first half of the original question:
using System;
namespace StackOverflowDemo
{
public class DemoProgram
{
public class Bar
{}
static void Main(string[] args)
{}
//?GrabMethodName
public void Foo(Bar arg)
{
//?DumpNameInStringAssignment
string methodName = "??"; // Will be changed as necessary by preprocessor
throw new ArgumentException("Argument is incompatible with " + methodName);
}
}
}
To make the running of the preprocessor program a part of the build process you modify the .csproj file in two places. Insert this line in the first section:
<UseHostCompilerIfAvailable>false</UseHostCompilerIfAvailable>
(This is optional - see here https://stackoverflow.com/a/12163384/253938 for more information.)
And at the end of the .csproj file replace some lines that are commented-out with these lines:
<Target Name="BeforeBuild">
<Exec WorkingDirectory="D:\Merlinia\Trunk-Debug\Common\Build Tools\Merlinia Preprocessor\VS2012 projects\StackOverflowPreprocessor\bin" Command="StackOverflowPreprocessor.exe "$(MSBuildProjectFullPath)"" />
</Target>
Now when you recompile the test program the line that says
string methodName = "??"; // Will be changed as necessary by preprocessor
will be magically converted to say
string methodName = "Foo"; // Will be changed as necessary by preprocessor
OK?

Version 6 of C# has introduced the nameof operator which works like the name operator described in the examples of the question, but with some restrictions. Here are some examples and excerpts from the C# FAQ blog:
(if x == null) throw new ArgumentNullException(nameof(x));
You can put more elaborate dotted names in a nameof expression, but that’s just to tell the compiler where to look: only the final identifier will be used:
WriteLine(nameof(person.Address.ZipCode)); // prints "ZipCode"
Note: there are small design changes to nameof since the Preview was built. In the preview, dotted expressions like in the last example, where person is a variable in scope, are not allowed. Instead you have to dot in through the type.

Not all paths return a value. - Optional return?

I am getting the error "Not all paths return a value", and I totally understand why.
As you can see I want to redirect the person isn't logged in, and obviously there is no return view.
I'm sure I'm going about this incorrectly. How should I be trying to do this?
public ActionResult Confirmation (Order Order) {
if (Session["CompanyID"] == null)
{
string url = Request.Url.Host;
if (Request.Url.Port != null)
{
url = url + Request.Url.Port;
}
url = url + "/signin.asp";
Response.Redirect(url);
}
else
{
int userID = (int)Session["CompanyID"];
Corp_User User = Repository.CorpUserDetails(userID);
return View(new OrderLocation { Order = Order, Location = WhygoRepository.RoomDetails(Order.roomId).First(), Corp_User = User });
}
}
Please note that I need to redirect to a classic ASP page, not an MVC action..

You must return a ActionResult. Use "RedirectToAction".
public ActionResult Confirmation(Order Order)
{
if (Session["CompanyID"] == null)
{
string url = Request.Url.Host;
if (Request.Url.Port != null)
{
url = url + Request.Url.Port;
}
url = url + "/signin.asp";
return RedirectToAction(<YOUR ACTION>);
}
else
{
int userID = (int)Session["CompanyID"];
Corp_User User = Repository.CorpUserDetails(userID);
return View(new OrderLocation { Order = Order, Location = WhygoRepository.RoomDetails(Order.roomId).First(), Corp_User = User });
}
}

You could return a RedirectResult - http://msdn.microsoft.com/en-us/library/system.web.mvc.redirectresult.aspx

Well, this is a good question actually. See dknaack's answer for a solution in your particular case however in other circumstances we might not be so lucky.
Technically this situation is very logical. Redirect just opens up a new request and either lets the current request handle itself nicely or forcefully close itself. In all cases the current method needs a return value. If Redirect lets the current process handle itself nicely meaning you should have a return value that makes sense.
I think one solution would be to throw a specific exception after the redirect. Something like:
public string GetCurrentUserName()
{
if (!authenticated)
{
Response.Redirect(LoginScreen);
throw new UnresolvedMethodException();
}
else
{
return UserName;
}
}
Returning NULL is an option i wouldnt put my money on since NULL might also mean that there is no UserName Set (in the above case, a user might login using his email making the username optional).

Just put return null; under Response.Redirect(url); It will never actually reach that position, but it will get rid of the compiler error.

You could return null and check for that.
edit: I was way to quick, ignore me :P

help with NullReference exception in C#

The following is a web method that is called from ajax, I have verified with firebug that the script is indeed passing two string values to my method:
public string DealerLogin_Click(string name, string pass)
{
string g="adf";
if (name == "w" && pass == "w")
{
HttpContext.Current.Session["public"] = "pub";
g= "window.location = '/secure/Default.aspx'";
}
return g;
}
I'm passing "w" just for testing purposes. If I delete the if block then I don't get an error back from the server. I'm confused.

Without seeing the stack trace, I would guess that HttpContext.Current or HttpContext.Current.Session is null.

Jeff is correct, but I wanted to add that using session within a web service requires that session be turned "on":
[WebMethod(EnableSession=true)]
public string DealerLogin_Click(string name, string pass)
{
string g="";
if (name == "w" && pass == "w")
{
Session["Public"]="pub";
g= "window.location = '/secure/Default.aspx'";
}
return g;
}