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GetManifestResourceStream returns NULL

This is a C# .NET 4.0 application:
I'm embedding a text file as a resource and then trying to display it in a dialog box:
var assembly = Assembly.GetExecutingAssembly();
var resourceName = "MyProj.Help.txt";
using (Stream stream = assembly.GetManifestResourceStream(resourceName))
{
using (StreamReader reader = new StreamReader(stream))
{
string result = reader.ReadToEnd();
System.Windows.Forms.MessageBox.Show(result, "MyProj", MessageBoxButtons.OK);
}
}
The solution is MyProjSolution and the executable is MyProj.exe. Help.txt is an embedded resource. However, the stream is null. I've tried MyProjSolution.Help.txt and MyProjSolution.MyProj.Help.txt but nothing seems to work.

You can check that the resources are correctly embedded by using
//From the assembly where this code lives!
this.GetType().Assembly.GetManifestResourceNames()
//or from the entry point to the application - there is a difference!
Assembly.GetExecutingAssembly().GetManifestResourceNames()
when debugging. This will list all the (fully qualified) names of all resources embedded in the assembly your code is written in.
See Assembly.GetManifestResourceNames() on MSDN.
Simply copy the relevant name, and use that instead of whatever you have defined in the variable 'resourceName'.
Notes - the resource name is case sensitive, and if you have incorrectly embedded the resource file, it will not show up in the list returned by the call to GetManifestResourceNames(). Also - make sure you are reading the resource from the correct assembly (if multiple assemblies are used) - it's all too easy to get the resources from the currently executing assembly rather than from a referenced assembly.
EDIT - .NET Core
Please see this SO post for details on how to embed using .NET Core.
Retrieving the manifest info looks to be similar - just use this.GetType().GetTypeInfo().Assembly.GetManifestResourceNames() to get the a manifest from the assembly where the code is executing.
I haven't figured out how to do the equivalent of Assembly.GetExecutingAssembly() in .NET Core yet! if anyone knows - please let me know and I will update this answer.

I had a similar issue check first that the file is included in your project , then go to properties and set the build action of that file to Embedded Resource . this worked for me .

The embedded file's "Build Action" property should be set as "Embedded Resource" to run the line, which is given below, properly:
Stream stream = assembly.GetManifestResourceStream(resourceName)
Right click on the file, click the property and then set "Build Action" property as "Embedded Resource":

Here is the cause of my null value.
http://adrianmejia.com/blog/2011/07/18/cs-getmanifestresourcestream-gotcha/
The GetManifestResourceStream method will always returns NULL if the resource ‘built action‘ property is not set to ‘embedded resource‘
After setting this property with all the needed files assembly.GetManifestResourceStream starts returning the correct stream instead of NULL.

Just a warning.
I could not access my file as an embedded resource even though I specified that it was and even though it had that Build Action property. Wasted a lot of time banging my head. I embedded a csharp code file with .txt appended to its name (xxx.cs.txt). For some reason the GetManifestResourceNames() and GetManifestResourceStream() methods won't see a file with .cs in its name.
I renamed it simply xxx.txt and everything was fine.
Weird.

In my case the problem was that the code looking for the resource was in a different project that the resource itself.
You can only access resources that are in the same project the code is. I thought I could put all my resources in the web page project, but I need images in the mail project too.
Hope this helps someone in the same situation I was.
I find really useful calling Assembly.GetExecutingAssembly().GetManifestResourceNames();.

I had the same problem, thanks to Jay I found it was hyphens in the directory name.
ProjectName.ResourceFolder.Sub-Directory becomes ProjectName.ResourceFolder.Sub_Directory when you reference the resource stream.

A simple and streamlined solution is to have this base class:
public class EmbededResourceReader
{
protected string LoadString(string fileName)
{
return LoadString(fileName, Encoding.UTF8);
}
protected string LoadString(string fileName, Encoding encoding)
{
var assembly = this.GetType().Assembly;
var resourceStream = assembly.GetManifestResourceStream($"{this.GetType().Namespace}.{fileName}");
using (var reader = new StreamReader(resourceStream, encoding))
{
return reader.ReadToEnd();
}
}
}
Then, when you add a resource, you create a reader C# class in the same folder:
where the reader class MyResource.cs is very simple:
public class MyResource : EmbededResourceReader
{
public string LoadString() => LoadString($"{nameof(MyResource)}.txt");
}
So, each resource will have a "shadow" class that knows how to read it properly.
This is how you read the resource in your code:
var text = new MyResource().LoadString();
And as other answers suggested, do not forget to set "Embedded Resource" in the Build Action property of the resource file.
The advantage of this uniform solution is
less hassle with finding correct full name of the resource, especially when placed in nested folders
in case when folder is renamed OR Default Namespace in project settings is changed, the code will NOT break

In case it helps anyone else, Make sure Assembly.GetExecutingAssembly() line is called from same assembly which has embedded resources.

First Unload the project and click on edit the project file.
Inside the project file make sure that the item you are fetching from the assembly is included inside <EmbeddedResource> tag.
Eg:
<ItemGroup>
<EmbeddedResource Include="Template\ForExampleFile.html" />
</ItemGroup>
The files I added into the project were just in Content tag but not in the EmbeddedResource as shown below by default. Hence the stream was returning null.
<ItemGroup>
<Content Include="Template\ForExampleFile.html" />
</ItemGroup>

You need to unload your solution.Then edit project.Afterfind your folder and change like this:
<EmbeddedResource Include="yourpath" />

Although OP got GetManifestResourceStream returning NULL from resources in the same Assembly, some Answers suggested that when Resources are in another Project or Assembly they cannot be retrieved, and are a fair cause of GetManifestResourceStream returning NULL.
This is not true, at least since 2011; as I pointed in some comments elsewhere, Assembly.LoadFrom() or typeof do the trick and as a result you can access resources that are in another project.
I have a moderately complex example here to illustrate; this is my test setup:
Path to another project:
Captured here:
var sharedXMLResource =
"D:\\My Documents\\Consultório Impressos\\DB Pacientes\\Teste\\TestesVariados\\WinFormFramework\\Read_Embedded_XML_File_CS\\bin\\Debug\\Read_Embedded_XML_File_CS.exe";
And on Form1.cs from WinFormFramework I specify with
Namespace.Folder.Resource
like that:
StreamReader reader =
new StreamReader(Assembly.LoadFrom(sharedXMLResource).GetManifestResourceStream("Read_Embedded_XML_File_CS.SharedResources.ContactList.xml") ?? throw new InvalidOperationException());
And the result displayed at textbox:
I spent several hours to get it right; for that, I had to use a lot these at Immediate Window:
Environment.CurrentDirectory
AppDomain.CurrentDomain.BaseDirectory
System.Reflection.Assembly.GetExecutingAssembly().Location
System.Reflection.Assembly.GetAssembly(typeof(WinFormFramework.Program)).Location
Hope it helps someone

I know this is an old question, however, I stumbled through this and with the help of #Jay answer I was able to get this working.
I had to use the full filename to get this to work.
using var stream = assembly.GetManifestResourceStream("Project.Folder.appsettings.json");

You probably need to specify the path to your txt file in the GetManifestResourceStream parameter, or you could try sticking the txt file in the same directory as your executable. Hope that helps!

Streaming MP3 Chunks on ASP.NET

Currently, I have a feature on an ASP.NET website where the user can play back MP3 Files. The code looks something like this:
Response.Clear();
Response.ContentType = "audio/mpeg";
foreach (DataChunk leChunk in db.Mp3Files.First(mp3 => mp3.Mp3ResourceId.Equals(id)).Data.Chunks.OrderBy(chunk => chunk.ChunkOrder))
{
Response.BinaryWrite(leChunk.Data);
}
Unfortunately, if a larger MP3 file is selected, the audio does not begin to play until the entire file is downloaded, which can cause a noticeable delay. Is there any way to get the MP3 to start playing immediately, even though the entire file may not yet be transferred?

You should be able to do what you want by writing to the outpstream of the response, i.e.:
Response.OutputStream.Write
It is also probably a good idea to check previously if Response.IsClientConnected and give up if not.
I found a demo that allows playback of mp3 files from an asp.net web application:
http://aspsnippets.com/Articles/Save-MP3-Audio-Files-to-database-and-display-in-ASPNet-GridView-with-Play-and-Download-option.aspx

try this:
Response.BufferOutput = false; //sets chunked encoding
Response.ContentType = "audio/mpeg";
using (var bw = new BinaryWriter(Response.OutputStream))
{
foreach (DataChunk leChunk in db.Mp3Files.First(mp3 => mp3.Mp3ResourceId.Equals(id)).Data.Chunks.OrderBy(chunk => chunk.ChunkOrder))
{
if (Response.IsClientConnected) //avoids the host closed the connection exception
{
bw.Write(leChunk.Data);
}
}
}
Also, go yo your web.config file and do this if you still have problems with chunked encoding:
<system.webServer>
<asp enableChunkedEncoding="true" />
</system.webServer>
The error you reported above about the host being closing the connection is happening probably because you are opening the page using the browser and when the browser reads the content type, it opens the media player and closes itself who had the opened connection which was then closed, causing that error, so to avoid this, you need to check periodically whether your client is still connected or not.
Finally, I would use a Generic Handler (.ashx) or a custom handler and set a .mp3 extension for this if you are using a aspx page to avoid the unnecessary overhead of the web page.
I hope this helps.

Try setting Response.BufferOutput = false before streaming the response.

If the location of the MP3 files are publicly available to your user then an alternative approach could be to just return the MP3's URL and use the HTML 5 audio tags in your mark up to stream the music. I am pretty sure that the default behaviour of the audio tag would be to stream the file rather than wait until the whole file has downloaded.

One method to support this would be implementing HTTP byte range requests.
By default I don't believe that ASP.NET does this, and definitely won't if using any of the code in the questions or the answer.
You can implement this manually with a little work though. Another option, which would be much less dev work, would be to let IIS serve a static file. I assume that isn't an option though.
Here's an example implementation:
http://www.codeproject.com/Articles/820146/HTTP-Partial-Content-In-ASP-NET-Web-API-Video

How to read file in C# from POST data from web

Basically, I'm building a website that allows user to upload file.
From the front end (JavaScript), the user will browse a file, I can get the site to send POST data (the parameter "UploadInput" and it's value, which the value is the file)
In the backend (C#), I want to make a copy of the file and save it in a specific path.
Below is the way I did it.
var files = Request.Files;
file[0].SaveAs("\temp\\" + file[0].FileName);
The problem I ran into is that I got the error message saying index out of range. I tried Response.Write(files.Count) and it gives me 0 instead of 1.
I'm wondering where I did wrong and how to fix it, or if there's a better way of doing it.
Thanks!
Edit:
I am using HttpFox to debug. From HttpFox, I can see that under POST data, parameter is "UploadInput" and the value is "test.txt"
Edit 2:
So I tried the way Marc provides, and I have a different problem.
I am able to create a new file, however, the content is not copied over. I tried opening the new created file in notepad and all it says is "UploadInput = test.txt"

If they simply posted the file as the body content, then there will be zero "files" involved here, so file[0] will fail. Instead, you need to look at the input-stream, and simply read from that stream. For example:
using(var file = File.Create(somePath)) {
Request.InputStream.CopyTo(file);
}

Place Image from DLL onto a web page

I'm so stuck on something i thought would be easy.
I have a DLL that returns an Image object.
I just cant figure out how to display that image on a webpage.
I've tried a few ways, and google a million different variations.
Is it not possible to just bind an Image object to an element on the page like an HtmlImage or a simple img?
Or do i need to convert the Image to a Stream? or a Bitmap? I'm really stuck!
Any help appreciated.....
V

With Asp.Net WebForm, the easiest way is to create a custom ashx file.
In Visual Studio, create a new Custom Handler (I'm not sure of the name of the template in Visual Studio). This will create a .ashx file.
In the code of this handler, write something like (does not have VS under the hand to test the syntax) :
public void ProcessRequest(System.Web.HttpContext context)
{
byte[] raw;
using(var ms = new MemoryStream()){
Image myImage = GetFromDll();
myImage.Save(ms, ImageFormat.Png);
raw=ms.ToArray();
}
context.Response.ContentType = "image/png";
context.Response.BinaryWrite(raw);
}
Then, in your browser, navigate to http://yourserver/app/yourhandler.ashx.
You can if you want add url parameter, and get it from the Request.QueryString collection

It's not as simple as binding. On the client side images are retrieved from the web server as a separate GET request, which means you have to have a URL that resolves to an image. The other option, as Asif suggested, is embedding your image in the HTML as a Base64 string, which is bad practice for shared images (see Steve B's comment).
You either have to provide an URL (route that returns the image file in MVC, or a custom page with proper content type and Response.Write in WebForms), or embed in html.
EDIT:
There is also a third option involving custom HTTP handlers. These have the advantage of bypassing the app framework and serving the content almost directly off the web server, see MSDN.

Convert your image to base64 string and then set it in the <img/> tag.
<img/> can show the image in base64 string.
Alternatively you can save the image and use the path in the <img/>.

Adding a file to a project, that will be added to the exe, and be accessable at runtime

I have a file (an xml), that is accessed in my code, I would like it to be some how added to the executable, so my utility can access it at runtime, but still be all in one file. Is there a way to doing that? (C#)
Thanks.

Look at embedded resources (first result from a Google search, but looks good at first glance)
Actually this article has the advantage of actually telling you how to make something an embedded resource. Between the two of them you should be able to sort out your problem.

Add it as an embedded resource (set the build action for the file to be "Embedded Resource") and use Assembly.GetManifestResourceStream to access it.
Be aware that when accessing a resource stream the name is case sensitive.

In the properties windows, set the properties Build Action as Embedded Resource.
After that you can access your file like this:
Assembly assbl = Assembly.GetAssembly(this.GetType());
using(Stream s = assbl.GetManifestResourceStream("projectnamespace.embeddedfilename.xml"))
{
XmlDocument doc = new XmlDocument();
using (StreamReader reader = new StreamReader(s))
{
doc.LoadXml(reader.ReadToEnd());
reader.Close();
}
}
In GetManifestResourceStream, you need to specify the "path" of your file in your project.