Develop Reference

Referencing a file inside of a Project without using its absolute path?

I'm using StreamReader to dynamically replace content in an HTML template. The HTML file has been imported into my project.
Right now I'm having to referencing the HTML file a static location on my dev box because I'm not able to find the right syntax to reference it once it's been imported into my VS project.
How do I refer to the file without using an absolute path?
Current implementation for reference:
StreamReader reader = new StreamReader(#"C:\Users\n00b\Desktop\EmailTemplate.html");
{
body = reader.ReadToEnd();
}

One common thing I've seen is to put the file's location in a configuration file. This lets you change the file location at will without having to recompile.

You can add it as an embedded resource and extract it this way.
using (Stream stream = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("<namespace>.Resources.EmailTemplate.html"))
per your comment
using (System.IO.StreamReader sr = new StreamReader(System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("<namespace>.Resources.EmailTemplate.html"))
{
body = sr.ReadToEnd();
}

There are 2 main ways to do this, In a desktop application, the current directory of the .exe is set to the directory where it is launched from by default. Unless that is changed by launching the .exe by a shortcut with special settings, or by another process using a special feature, it should be the default value. If that is the case, you can just use a relative path. For example, if you have a file named "data.txt" in a folder called "things" inside a folder called "stuff" in the same directory as your app, you can just us the relative path "stuff/things/data.txt" directly and Windows will work it out for you.
If you need to be absolutely sure you are targeting that file, even if the app launches with a modified current directory, you can get the .exe's path, and combine it with a relative path using System.IO.Path.Combine.
var appPath = Assembly.GetEntryAssembly().Location;
var filePath = "stuff/things/data.txt"
var fullPath = System.IO.Path.Combine(appPath, filePath)
If, for some reason, you need to up "up" from the application's directory, you can use ".." to represent that parent folder of a directory. So "../data.txt" would look in the folder that contains the current directory for a file named "data.txt".
You could also change the app's current directory when it starts to be the directory of the .exe, and then reference everything via relative path, as in the first example.
var appPath = Assembly.GetEntryAssembly().Location;
System.IO.Directory.SetCurrentDirectory(appPath);

I found two solutions to this:
If you don't care if the external file is visible in the build directory/installdir of your app:
StreamReader reader = new StreamReader(#"../../EmailTemplate.html");
{
body = reader.ReadToEnd();
}
If you want your external file to be invisible once compiled:
var embeddedResource = "<namespace>.EmailTemplate.html";
using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(embeddedResource))
{
StreamReader sr = new StreamReader(stream);
body = sr.ReadToEnd();
}
Note the 2nd solution requires adding your external file and changing the build action to "Embedded Resource" on the properties menu of that file within Visual Studio.

asp.net web form C# Streamreader can't find the text file

Trying to make a silly web form that keeps some small information in a text file inside a "data" folder. The code is:
StreamReader sr = new StreamReader(Server.MapPath("data/FeatureList.txt"));
String FileText = sr.ReadToEnd().ToString();
sr.Close();
Getting an exception:
Could not find file 'C:\Users\Tom\Documents\Visual Studio 2013\WebSites\WebSite2\data\FeatureList.txt'.
And, naturally, the file is there right in the specified folder.
Perhaps I have a permission error and IIS can't read the folder or file? Maybe I need to tell Visual Studio 2013 something about this folder? I haven't played with one of these asp.net programs in a while, not since... Well, a couple years ago I made a web page that reads text files and adds captions to displayed photos.

You may use the Path.Combine , it is a good method to get a valid path
StreamReader sr = new StreamReader(Path.Combine(Server.MapPath("~"), #"data/FeatureList.txt"));
String FileText = sr.ReadToEnd().ToString();
sr.Close();

Try,
string path = (string.Format("{0}\\{1}", AppDomain.CurrentDomain.BaseDirectory,"\data\FeatureList.txt));

Path to read file from inside www folder

I have a binary reader to read a file
BinaryWriter bw2 = new BinaryWriter(File.Open(#"c:\test\test6.xml", FileMode.OpenOrCreate));
the path i have set to is c:\test\test.xml
However it needs to read the file from www folder hosted site
so www\test\test.xml
should it be ~\test\test.xml?
Not sure.
Thanks for your help

Check out Server.MapPath() http://msdn.microsoft.com/en-us/library/ms524632(v=VS.90).aspx
So in your case, you're after this:
using (BinaryWriter bw2 = new BinaryWriter(File.Open(Server.MapPath(#"~\test\test6.xml", FileMode.OpenOrCreate)))
{
...
}
Notice I added the using() which is a best-practice for working with expensive resources like files.
Of course, you really should seperate out file opening from object creation so you can have better diagnostics in your code.

Probably you need this function: http://msdn.microsoft.com/en-us/library/ms524632(v=vs.90).aspx

Regarding StreamReader

Why is this not working ?
StreamReader m = new StreamReader("../folder1/email.html", System.Text.Encoding.UTF8);
code file and html file are in diff folders so I that its some path issue but its not because I just now copied this html file in the same folder where this code file is and changed code to:
StreamReader m = new StreamReader("email.html", System.Text.Encoding.UTF8);
still not working.. What's wrong? Is the syntax wrong or what?

If you use a relative path it will be relative to the bin/Debug or bin/Release folder, not the project folder where your code file is, so try:
m= new StreamReader("../../email.html", System.Text.Encoding.UTF8);

You say that there's no exception with your code. This means that the file is successfully opened for reading. I suspect that you are not reading anything from this StreamReader, you are simply instantiating it and probably not releasing.
Make sure you dispose this stream or you might leak handles. If all you need to do is read the file contents you could use the ReadAllText method:
string contents = File.ReadAllText("email.html");
If the file is not found you will get an exception.

You are probably not reading it ...try this ...put the file in your Bin/Debug directory and...
StreamReader m = new StreamReader("email.html", System.Text.Encoding.UTF8);
Console.Write(m.ReadToEnd());
Console.ReadLine();

How can I create a file with StreamWriter using a relative path?

When I run the following code, an XML file is correctly created in c:\temp:
XmlSerializer xs = new XmlSerializer(typeof(ObservableCollection<Models.Customer>));
using (StreamWriter wr = new StreamWriter("C:/temp/CustomerMock2.xml"))
{
xs.Serialize(wr, CustomerList);
}
However, I actually want it to be created in a sub-directory underneath the project, but when I do this:
using (StreamWriter wr = new StreamWriter("Data/CustomerMock2.xml"))
it just acts as if it writes it but the file never appears in that directory:
C:\Projects\Prototype12\CustomersModul\bin\Debug\Data.
How can I create a file with StreamWriter with a relative path inside my project?

It is always dangerous to rely on the 'Current Directory' concept, so you will need a starting point. In a WinForms project, you can get the location of the .EXE with
string exeFolder = System.IO.Path.GetDirectoryName(Application.ExecutablePath);
In WPF there will be something similar.
But if you are in a library and do not have access to the Application (or Environment) objects, you should consider making a BaseFolder parameter or property to let the main application take control over folders.

Does ./Data/CustomerMock2.xml work?
using (StreamWriter wr = new StreamWriter("./Data/CustomerMock2.xml"))

Are you setting the XML data to be copied at compile time (so it's not in the actual project directory, but the bin folder)? In which case you can get to it using
string xmlFile = string.Format("{0}/Data/{1}",AppDomain.CurrentDomain.BaseDirectory,"myxml.xml");

Relative paths are relative to the current directory. Maybe you're not in the bin/debug directory... You should build the absolute path based on the exe directory, as shown by Chris.
Also, the StreamWriter constructor won't create the directory, you need to create it explicitly if it doesn't exist.