ASP.NET has specicial application folders like App_Code which:
Contains source code for shared classes and business objects (for example, ..cs, and .vb files) that you want to compile as part of your application. In a dynamically compiled Web site project, ASP.NET compiles the code in the App_Code folder on the initial request to your application. Items in this folder are then recompiled when any changes are detected.
Problem is, I'm building a web application, not a dynamically compiled web site. But I'd love to be able to store config values directly in C#, rather than serve via an XML and have to read in during Application_Start and store in HttpContext.Current.Application
So I have the following code in /App_Code/Globals.cs:
namespace AppName.Globals
{
public static class Messages
{
public const string CodeNotFound = "The entered code was not found";
}
}
Which could be anywhere within the application like this:
string msg = AppName.Globals.Messages.CodeNotFound;
The goal is to be able to store any literals in a configurable area that can be updated without recompiling the entire application.
I can use the .cs file by setting its build action to compile, but doing so strips out App_Code/Globals.cs from my output.
Q: Is there a way to identify some parts of a project that should dynamically compile while allowing the rest of the project to be precompiled?
If I set the build action to content - the .cs file will get copied to the bin folder and compiled at runtime. However, in that case, it's not available at design time.
If I set the build action to compile - I can access the objects the same as any other compiled class during design/runtime, but it'll get stripped out of the /App_Code folder when published. I can still place it in the output directory via Copy Always, but the already compiled classes seem to take priority so I can't push config changes without re-deploying the whole application.
Problem Overview
We need to overcome two different problems here:
The first is having a single file that can be compiled at build time and also re-compiled at runtime.
The second is resolving the two different versions of that class created by the solving the first problem so we can actually make use of them.
Problem 1 - Schrödinger's Compilation
The first problem is trying to get a class that is both compiled and not compiled. We need to compile it at design time so that other sections of code are aware it exists and can use its properties with strong typing. But normally, compiled code is stripped out of the output so there aren't multiple versions of the same class causing naming conflicts.
In any case, we need to compile the class initially, but there are two options to persist a re-compilable copy:
Add the file to App_Code, which is compiled at runtime by default, but set it's Build Action = Compile so it's available at design time as well.
Add a regular class file, which is compiled at design time by default, but set it to Copy to Output Directory = Copy Always, so there's a chance we can evaluate it at runtime as well.
Problem 2 - Self Imposed DLL Hell
At a bare minimum, this is a tricky task to charge to the compiler. Any code that consumes a class, must have a guarantee that it exists at compile time. Anything that is dynamically compiled, whether via App_Code or otherwise, will be part of an entirely different assembly. So producing an identical class is treated more like a picture of that class. The underlying type might be the same, but ce n'est une pipe.
We have two options: use an interface or crosswalk between assemblies:
If we use an interface, we can compile it with the initial build and any dynamic types can implement that same interface. This way we are safely relying on something that exists at compile time, and our created class can be safely swapped out as a backing property.
If we cast types across assemblies, it's important to note that any existing usages rely on the type that was originally compiled. So we'll need to grab the values from the dynamic type and apply those property values to the original type.
Existing Answers
Per evk, I like the idea of querying AppDomain.CurrentDomain.GetAssemblies() on startup to check for any new assemblies/classes. I'll admit that using an interface is probably an advisable way to unify precompiled/dynamically compiled classes, but I would ideally like to have a single file/class that can simply be re-read if it changes.
Per S.Deepika, I like the idea of dynamically compiling from a file, but don't want to have to move the values to a separate project.
Ruling out App_Code
App_Code does unlock the ability to build two versions of the same class, but it's actually hard to modify either one after publication as we'll see. Any .cs file located in ~/App_Code/ will be dynamically compiled when the application runs. So in Visual Studio, we can build the same class twice by adding it to App_Code and setting the Build Action to Compile.
Build Action and Copy Output:
When we debug locally, all .cs files will be built into the project assembly and the physical file in ~/App_Code will also be built as well.
We can identify both types like this:
// have to return as object (not T), because we have two different classes
public List<(Assembly asm, object instance, bool isDynamic)> FindLoadedTypes<T>()
{
var matches = from asm in AppDomain.CurrentDomain.GetAssemblies()
from type in asm.GetTypes()
where type.FullName == typeof(T).FullName
select (asm,
instance: Activator.CreateInstance(type),
isDynamic: asm.GetCustomAttribute<GeneratedCodeAttribute>() != null);
return matches.ToList();
}
var loadedTypes = FindLoadedTypes<Apple>();
Compiled and Dynamic Types:
This is really close to solving problem #1. We have access to both types every time the app runs. We can use the compiled version at design time and any changes to the file itself will automatically be recompiled by IIS into a version that we can access at runtime.
The problem is apparent however once we step out of debug mode and try to publish the project. This solution relies on IIS building the App_Code.xxxx assembly dynamically, and that relies on the .cs file being inside the root App_Code folder. However, when a .cs file is compiled, it is automatically stripped out of the published project, to avoid the exact scenario we're trying to create (and delicately manage). If the file was left in, it would produce two identical classes, which would create naming conflicts whenever either one was used.
We can try to force its hand by both compiling the file into the project's assembly and also copying the file into the output directory. But App_Code doesn't work any of it's magic inside of ~/bin/App_Code/. It'll only work at the root level ~/App_Code/
App_Code Compilation Source:
With every publish, we could manually cut and paste the generated App_Code folder from the bin and place it back at the root level, but that's precarious at best. Perhaps we could automate that into build events, but we'll try something else...
Solution
Compile + (Copy to Output and Manually Compile File)
Let's avoid the App_Code folder because it will add some unintended consequences.
Just create a new folder named Config and add a class that will store the values we want to be able to modify dynamically:
~/Config/AppleValues.cs:
public class Apple
{
public string StemColor { get; set; } = "Brown";
public string LeafColor { get; set; } = "Green";
public string BodyColor { get; set; } = "Red";
}
Again, we'll want to go to the file properties (F4) and set to compile AND copy to output. This will give us a second version of the file we can use later.
We'll consume this class by using it within a static class that exposes the values from anywhere. This helps separate concerns, especially between the need to dynamically compile and statically access.
~/Config/GlobalConfig.cs:
public static class Global
{
// static constructor
static Global()
{
// sub out static property value
// TODO magic happens here - read in file, compile, and assign new values
Apple = new Apple();
}
public static Apple Apple { get; set; }
}
And we can use it like this:
var x = Global.Apple.BodyColor;
What we'll attempt to do inside the static constructor, is seed Apple with the values from our dynamic class. This method will be called once every time the application is restarted, and any changes to the bin folder will automatically trigger recycling the app pool.
In short order, here's what we'll want to accomplish inside of the constructor:
string fileName = HostingEnvironment.MapPath("~/bin/Config/AppleValues.cs");
var dynamicAsm = Utilities.BuildFileIntoAssembly(fileName);
var dynamicApple = Utilities.GetTypeFromAssembly(dynamicAsm, typeof(Apple).FullName);
var precompApple = new Apple();
var updatedApple = Utilities.CopyProperties(dynamicApple, precompApple);
// set static property
Apple = updatedApple;
fileName - The File path might be specific to where you'd like to deploy this, but note that inside of a static method, you need to use HostingEnvironment.MapPath instead of Server.MapPath
BuildFileIntoAssembly - In terms of loading the assembly from a file, I've adapted the code from the docs on CSharpCodeProvider and this question on How to load a class from a .cs file. Also, rather than fight dependencies, I just gave the compiler access to every assembly that was currently in the App Domain, same as it would have gotten on the original compilation. There's probably a way to do that with less overhead, but it's a one time cost so who cares.
CopyProperties - To map the new properties onto the old object, I've adapted the method in this question on how to Apply properties values from one object to another of the same type automatically? which will use reflection to break down both objects and iterate over each property.
Utilities.cs
Here's the full source code for the Utility methods from above
public static class Utilities
{
/// <summary>
/// Build File Into Assembly
/// </summary>
/// <param name="sourceName"></param>
/// <returns>https://msdn.microsoft.com/en-us/library/microsoft.csharp.csharpcodeprovider.aspx</returns>
public static Assembly BuildFileIntoAssembly(String fileName)
{
if (!File.Exists(fileName))
throw new FileNotFoundException($"File '{fileName}' does not exist");
// Select the code provider based on the input file extension
FileInfo sourceFile = new FileInfo(fileName);
string providerName = sourceFile.Extension.ToUpper() == ".CS" ? "CSharp" :
sourceFile.Extension.ToUpper() == ".VB" ? "VisualBasic" : "";
if (providerName == "")
throw new ArgumentException("Source file must have a .cs or .vb extension");
CodeDomProvider provider = CodeDomProvider.CreateProvider(providerName);
CompilerParameters cp = new CompilerParameters();
// just add every currently loaded assembly:
// https://stackoverflow.com/a/1020547/1366033
var assemblies = from asm in AppDomain.CurrentDomain.GetAssemblies()
where !asm.IsDynamic
select asm.Location;
cp.ReferencedAssemblies.AddRange(assemblies.ToArray());
cp.GenerateExecutable = false; // Generate a class library
cp.GenerateInMemory = true; // Don't Save the assembly as a physical file.
cp.TreatWarningsAsErrors = false; // Set whether to treat all warnings as errors.
// Invoke compilation of the source file.
CompilerResults cr = provider.CompileAssemblyFromFile(cp, fileName);
if (cr.Errors.Count > 0)
throw new Exception("Errors compiling {0}. " +
string.Join(";", cr.Errors.Cast<CompilerError>().Select(x => x.ToString())));
return cr.CompiledAssembly;
}
// have to use FullName not full equality because different classes that look the same
public static object GetTypeFromAssembly(Assembly asm, String typeName)
{
var inst = from type in asm.GetTypes()
where type.FullName == typeName
select Activator.CreateInstance(type);
return inst.First();
}
/// <summary>
/// Extension for 'Object' that copies the properties to a destination object.
/// </summary>
/// <param name="source">The source</param>
/// <param name="target">The target</param>
/// <remarks>
/// https://stackoverflow.com/q/930433/1366033
/// </remarks>
public static T2 CopyProperties<T1, T2>(T1 source, T2 target)
{
// If any this null throw an exception
if (source == null || target == null)
throw new ArgumentNullException("Source or/and Destination Objects are null");
// Getting the Types of the objects
Type typeTar = target.GetType();
Type typeSrc = source.GetType();
// Collect all the valid properties to map
var results = from srcProp in typeSrc.GetProperties()
let targetProperty = typeTar.GetProperty(srcProp.Name)
where srcProp.CanRead
&& targetProperty != null
&& (targetProperty.GetSetMethod(true) != null && !targetProperty.GetSetMethod(true).IsPrivate)
&& (targetProperty.GetSetMethod().Attributes & MethodAttributes.Static) == 0
&& targetProperty.PropertyType.IsAssignableFrom(srcProp.PropertyType)
select (sourceProperty: srcProp, targetProperty: targetProperty);
//map the properties
foreach (var props in results)
{
props.targetProperty.SetValue(target, props.sourceProperty.GetValue(source, null), null);
}
return target;
}
}
But Why Tho?
Okay, so there are other more conventional ways to accomplish the same goal. Ideally, we'd shoot for Convention > Configuration. But this provides the absolute easiest, most flexible, strongly typed way to store config values I've ever seen.
Normally config values are read in via an XML in an equally odd process that relies on magic strings and weak typing. We have to call MapPath to get to the store of value and then do Object Relational Mapping from XML to C#. Instead here, we have the final type from the get go, and we can automate all of the ORM work between identical classes that just happen to be compiled against different assemblies.
In either case, the dream output of that process is to be able to write and consume C# directly. In this case, if I want to add an extra, fully configurable property, it's as easy as adding a property to the class. Done!
It will be available immediately and recompiled automatically if that value changes without needing to publish a new build of the app.
Dynamically Changing Class Demo:
Here's the full, working source code for the project:
Compiled Config - Github Source Code | Download Link
You can move configuration part to separate project, and create common interface like (IApplicationConfiguration.ReadConfiguration) to access it.
You can compile the code dynamically at run time like below, and you can access the configuration details using reflection.
public static Assembly CompileAssembly(string[] sourceFiles, string outputAssemblyPath)
{
var codeProvider = new CSharpCodeProvider();
var compilerParameters = new CompilerParameters
{
GenerateExecutable = false,
GenerateInMemory = false,
IncludeDebugInformation = true,
OutputAssembly = outputAssemblyPath
};
// Add CSharpSimpleScripting.exe as a reference to Scripts.dll to expose interfaces
compilerParameters.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().Location);
var result = codeProvider.CompileAssemblyFromFile(compilerParameters, sourceFiles); // Compile
return result.CompiledAssembly;
}
Let's see how dynamic compilation of files in App_Code works. When first request to your application arrives, asp.net will compile code files in that folder into assembly (if were not compiled before), and then load that assembly into current application domain of asp.net application. That's why you see your message in a watch - assembly was compiled and is available in current app domain. Because it was compiled dynamically, of course you have compile-time error when trying to reference it explicitly - this code is not yet compiled, and when it will be compiled - it might have completely different structure and message you reference might just not be there at all. So there is no way you can explicitly reference code from dynamic-generated assembly.
What options do you have then? For example, you can have an interface for your messages:
// this interface is located in your main application code,
// not in App_Code folder
public interface IMessages {
string CodeNotFound { get; }
}
Then, in your App_Code file - implement that interface:
// this is in App_Code folder,
// you can reference code from main application here,
// such as IMessages interface
public class Messages : IMessages {
public string CodeNotFound
{
get { return "The entered code was not found"; }
}
}
And then in main application - provide a proxy by searching current app domain for assembly with type that implements IMessage interface (only once, then cache it) and proxy all calls to that type:
public static class Messages {
// Lazy - search of app domain will be performed only on first call
private static readonly Lazy<IMessages> _messages = new Lazy<IMessages>(FindMessagesType, true);
private static IMessages FindMessagesType() {
// search all types in current app domain
foreach (var asm in AppDomain.CurrentDomain.GetAssemblies()) {
foreach (var type in asm.GetTypes()) {
if (type.GetInterfaces().Any(c => c == typeof(IMessages))) {
return (IMessages) Activator.CreateInstance(type);
}
}
}
throw new Exception("No implementations of IMessages interface were found");
}
// proxy to found instance
public static string CodeNotFound => _messages.Value.CodeNotFound;
}
This will achieve your goal - now when you change code in App_Code Messages class, on next request asp.net will tear down current application domain (first waiting for all pending requests to finish), then create new app domain, recompile your Messages and load into that new app domain (note that this recreating of app domain always happen when you change something in App_Code, not just in this particular situation). So next request will already see new value of your message without you explicitly recompile anything.
Note that you obviously cannot add or remove messages (or change their names) without recompiling main application, because doing that will require changes to IMessages interface which belongs to main application code. If you try - asp.net will throw compilation failure error on next (and all subsequent) requests.
I'd personally avoid doing such things, but if you are fine with that - why not.
Spending hours on this. Thinking my thought process might be off..
I wanted to create one point of entry for language translation across different libraries and applications.
What I did was the following:
Created New Class Library Project called Translations
At Root Level Added New Item - MyStrings.en-US.resx file
Populated resx file
resx - Access Modifier set to Public
At Root Level of Translations Project Added New Item Class - Translator
Added Property
public class Translator
{
private ResourceManager _translationManager;
public ResourceManager TranslationManager
{
get
{
if (_translationManager == null)
{
_translationManager = new ResourceManager("MyStrings", this.GetType().Assembly);
}
return _translationManager;
}
}
}
In WebSite (not web project but website) Added Reference to Translations Project
In the code behind declared
private Translator _translate;
public Translator Translate
{
get
{
if (_translate == null)
{
_translate = new Translator();
}
return _translate;
}
}
then in a LINQ statement
Title = TranslationManager.GetString(appsAvailable.Value.ResourceKey, CurrentCulture)
ResourceKey does have a value
CurrentCulture = en-US
And I am getting this error
Could not find any resources appropriate for the specified culture or
the neutral culture. Make sure "MyStrings.resources" was correctly
embedded or linked into assembly "Translations" at compile time, or
that all the satellite assemblies required are loadable and fully
signed.
When I look at my bin/obj/debug folder I am seeing this Translations.MyStrings.en-US.resources
which is not the name it is looking for. I have tried to modify the "basename" for the manager from "MyStrings" to 'Translations.MyStrings" but I get a similar error stating "Translations.MyStrings.resources" can't be found. I have also tried just saying okay forget the culture right now let's access it "Translations.MyStrings.en-US" as the base name. and it says it still can not find it.
Any ideas of where I am going wrong? I am thinking it needs to be copied somewhere so the software finds it but don't know where it goes? Or am I trying to do something that it is not meant to do?
Your help is greatly appreciated!
Just download MAT (Multilingual App Toolkit) for Visual Studio. https://marketplace.visualstudio.com/items?itemName=MultilingualAppToolkit.MultilingualAppToolkit-18308
This is the way to go to translate and maintain your projects in Visual Studio ;-)
https://blogs.msdn.microsoft.com/matdev/
Class Library A
Strings
en-US
Resources.resw
zh-CN
Resources.resw
Application
Views
ViewA.xaml
So I have a View, ViewA that I need to manually load localized strings from. However, whenever I do this, I receive an empty string.
I have tried:
var loader = ResourceLoader.GetForCurrentView();
var myLocalizedText = loader.GetString("Foo");
and
var loader = new ResourceLoader();
var myLocalizedText = loader.GetString("Foo");
The variable myLocalizedText is always an empty string.
I tried to reproduce your issue, however I just got ResourceMap Not Found. exception when using ResourceLoader.GetForCurrentView() or new ResourceLoader().
If we want to construct a resource loader for resources from a library package, we need use ResourceLoader.GetForCurrentView(String) method or ResourceLoader.ResourceLoader(String) constructor. Here the String is the resource identifier of the ResourceMap that the new resource loader uses for unqualified resource references.
Components or library files are typically added into a subfolder of the package they are included in during the build process, similar to their string resources. Their resource identifier usually takes the following form:
ClassLibraryOrAssemblyName/ResourceFileName/StringName
So for your case, we can use following code to load localized strings:
var loader = ResourceLoader.GetForCurrentView("ClassLibraryA/Resources");
var myLocalizedText = loader.GetString("Foo");
For more information, please see: Loading strings from libraries or controls and scenario 6 in Application resources and localization sample.
Besides, please note that for a UWP app, it's better to use GetForCurrentView(String) method:
[ResourceLoader(String) may be altered or unavailable for releases after Windows 8.1. Instead, use GetForCurrentView(String).]
Also if you want to add Chinese language, you'd better use zh-Hans instead of zh-CN:
Include script when there is no suppress script value defined for the language. See the IANA subtag registry for language tag details. For example, use zh-Hant, zh-Hant-TW, or zh-Hans, and not zh-CN or zh-TW.
For more information see: Qualify resources with their language.
When we want to make our application for all users(speak different languages),We need a global technology.
In C# we use ResourceManager as follow:
using System;
using System.Reflection;
using System.Resources;
public class Example
{
public static void Main()
{
// Retrieve the resource.
ResourceManager rm = new ResourceManager("ExampleResources" ,
typeof(Example).Assembly);
string greeting = rm.GetString("Greeting");
Console.Write("Enter your name: ");
string name = Console.ReadLine();
Console.WriteLine("{0} {1}!", greeting, name);
}
}
// The example produces output similar to the following:
// Enter your name: John
// Hello John!
The assembly have two or more language resources:
Assembly
|--Assembly.en-us.resx
|--Assembly.zh-cn.resx
Then we archive to change the resource by changing thread cultureinfo to use different resource.
If the application have a lot of dll(assembly) files.
I want to have a single point(one resource file for one language) for the application,
Is there a good solution for my idea?
Before I just change the View(eg.Winform or UserControl)'s Language to implement different UI for corresponding language.
Just build the internationalization in C# using the way you described. But as last step of the build process, you can run Fody.Costura.
This will take all the different dlls and pack them into your application so that you only have a single .exe file with everything included.
The benefit is that you can use the C# internationalization frameworks as intended without any hacks, but you still get a single exe you can deliver to your customers.
I find the C# internationalization frameworks very lacking, so I normally
make one assembly for resources and reference from the other projects. The resource files I generate from some tool (DB, excel, textfile) and keep both the source data and the resource files under version control.
MyApp.sln
ResourceProject.csproj
Resources.resx
Resources.ru.resx
Resources.de.resx
Resource.cs
Core.csproj
UI.csproj
The resource class can load all the different assemblies
namespace MyApp.Resources
{
public static class Resource
{
private static ResourceManager manager;
static Resource()
{
manager = new ResourceManager("MyApp.Resources", Assembly.GetAssembly(typeof(Resource)));
}
public static string GetString(string key, string culture)
{
return GetString(key, new CultureInfo(culture));
}
public static string GetString(string key, CultureInfo culture)
{
return manager.GetString(key, culture);
}
}
}
This simple class can be extended in various ways. In the calling assemblies you can have utility classes that will call based on the current UI culture or thread culture depending on the situation.
Note that this completely sidesteps any built-in WinForms or WPF i18N methods.
For GUI:s you can make a utility that recursively translates whole forms. The lookup itself can/should be extended with warnings for missing keys, fallback arguments, prefixes/namespaces if you have thousands of keys and so on.
I am working on an MVC application that is effectively a piece of middleware to provide admin and reporting on an external BPM solution.
The users of the system aren't all for the same business function and may refer to fields as different things (e.g. division A calls a client a Client but division B calls them a Prospect). Is there a way I could have resource files for
Resources.divA.resx
Resources.divB.resx
Resources.divC.resx
From my googling, it appears it can only be used for localization.
You can use the ResourceManager class to help with this.
When you add some resources to a project, the IDE automatically adds a Resources.Designer.cs file to the project to manage the resources. The generated code looks something like this:
[global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
internal static global::System.Resources.ResourceManager ResourceManager {
get {
if (object.ReferenceEquals(resourceMan, null)) {
global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("AssemblyName.Properties.Resources", typeof(Resources).Assembly);
resourceMan = temp;
}
return resourceMan;
}
}
This uses the ResourceManager constructor that looks up resources based on a combination of a root name and the current locale.
You can write similar code yourself, but compute a root name based on whether the the resources are for division A, B or C. So you would call it something like "AssemblyName.Resources.divA" instead of "AssemblyName.Properties.Resources".
You can then also have specific versions for each other supported language and they will be automatically loaded (if present) for the current culture. This is how it works for the IDE-managed resources.