I'll soon be working on a large c# project and would like to build in multi-language support from the start. I've had a play around and can get it working using a separate resource file for each language, then use a resource manager to load up the strings.
Are there any other good approaches that I could look into?
I can tell this from out experience, having a current solution with 12 24 projects that includes API, MVC, Project Libraries (Core functionalities), WPF and Xamarin. It is worth reading this long post as I think it is the best way to do so. With the help of VS tools easily exportable and importable to sent to translation agencies or review by other people.
EDIT 02/2018: Still going strong, converting it to a .NET Standard library makes it possible to even use it across .NET Framework and NET Core. I added an extra section for converting it to JSON so for example angular can use it.
EDIT: 2019: Going forward with Xamarin, this still works across all platforms. E.g. Xamarin.Forms advices to use resx files as well. (I did not develop an app in Xamarin.Forms yet, but the documentation, that is way to detailed to just get started, covers it: Xamarin.Forms Documentation). Just like converting it to JSON we can also convert it to a .xml file for Xamarin.Android (currently working on).
So, lets get to it.
Pro's
ResourceDirectories.Thread.CurrentThread.CurrentCultureCon's
Setup
Create language project in your solution, give it a name like MyProject.Language. Add a folder to it called Resources, and in that folder, create two Resources files (.resx). One called Resources.resx and another called Resources.en.resx (or .en-GB.resx for specific). In my implementation, I have NL (Dutch) language as the default language, so that goes in my first file, and English goes in my second file.
Setup should look like this:
The properties for Resources.resx must be:
Make sure that the custom tool namespace is set to your project namespace. Reason for this is that in WPF, you cannot reference to Resources inside XAML.
And inside the resource file, set the access modifier to Public:
Using in another project
Reference to your project: Right click on References -> Add Reference -> Prjects\Solutions.
Use namespace in a file: using MyProject.Language;
Use it like so in back-end:
string someText = Resources.orderGeneralError;
If there is something else called Resources, then just put in the entire namespace.
In MVC you can do however you like to set the language, but I used parameterized url's, which can be setup like so:
RouteConfig.cs Below the other mappings
routes.MapRoute(
name: "Locolized",
url: "{lang}/{controller}/{action}/{id}",
constraints: new { lang = @"(\w{2})|(\w{2}-\w{2})" }, // en or en-US
defaults: new { controller = "shop", action = "index", id = UrlParameter.Optional }
);
FilterConfig.cs (might need to be added, if so, add FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); to the Application_start() method in Global.asax
public class FilterConfig
{
public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new ErrorHandler.AiHandleErrorAttribute());
//filters.Add(new HandleErrorAttribute());
filters.Add(new LocalizationAttribute("nl-NL"), 0);
}
}
LocalizationAttribute
public class LocalizationAttribute : ActionFilterAttribute
{
private string _DefaultLanguage = "nl-NL";
private string[] allowedLanguages = { "nl", "en" };
public LocalizationAttribute(string defaultLanguage)
{
_DefaultLanguage = defaultLanguage;
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
string lang = (string) filterContext.RouteData.Values["lang"] ?? _DefaultLanguage;
LanguageHelper.SetLanguage(lang);
}
}
LanguageHelper just sets the Culture info.
//fixed number and date format for now, this can be improved.
public static void SetLanguage(LanguageEnum language)
{
string lang = "";
switch (language)
{
case LanguageEnum.NL:
lang = "nl-NL";
break;
case LanguageEnum.EN:
lang = "en-GB";
break;
case LanguageEnum.DE:
lang = "de-DE";
break;
}
try
{
NumberFormatInfo numberInfo = CultureInfo.CreateSpecificCulture("nl-NL").NumberFormat;
CultureInfo info = new CultureInfo(lang);
info.NumberFormat = numberInfo;
//later, we will if-else the language here
info.DateTimeFormat.DateSeparator = "/";
info.DateTimeFormat.ShortDatePattern = "dd/MM/yyyy";
Thread.CurrentThread.CurrentUICulture = info;
Thread.CurrentThread.CurrentCulture = info;
}
catch (Exception)
{
}
}
Usage in .cshtml
@using MyProject.Language;
<h3>@Resources.w_home_header</h3>
or if you don't want to define usings then just fill in the entire namespace OR you can define the namespace under /Views/web.config:
<system.web.webPages.razor>
<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<pages pageBaseType="System.Web.Mvc.WebViewPage">
<namespaces>
...
<add namespace="MyProject.Language" />
</namespaces>
</pages>
</system.web.webPages.razor>
This mvc implementation source tutorial: Awesome tutorial blog
Using in class libraries for models
Back-end using is the same, but just an example for using in attributes
using MyProject.Language;
namespace MyProject.Core.Models
{
public class RegisterViewModel
{
[Required(ErrorMessageResourceName = "accountEmailRequired", ErrorMessageResourceType = typeof(Resources))]
[EmailAddress]
[Display(Name = "Email")]
public string Email { get; set; }
}
}
If you have reshaper it will automatically check if the given resource name exists. If you prefer type safety you can use T4 templates to generate an enum
Ofcourse add a reference to your MyProject.Language namespace, we know how to use it in back-end.
In XAML, inside the header of a Window or UserControl, add a namespace reference called lang like so:
<UserControl x:Class="Babywatcher.App.Windows.Views.LoginView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:MyProject.App.Windows.Views"
xmlns:lang="clr-namespace:MyProject.Language;assembly=MyProject.Language" <!--this one-->
mc:Ignorable="d"
d:DesignHeight="210" d:DesignWidth="300">
Then, inside a label:
<Label x:Name="lblHeader" Content="{x:Static lang:Resources.w_home_header}" TextBlock.FontSize="20" HorizontalAlignment="Center"/>
Since it is strongly typed you are sure the resource string exists. You might need to recompile the project sometimes during setup, WPF is sometimes buggy with new namespaces.
One more thing for WPF, set the language inside the App.xaml.cs. You can do your own implementation (choose during installation) or let the system decide.
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
SetLanguageDictionary();
}
private void SetLanguageDictionary()
{
switch (Thread.CurrentThread.CurrentCulture.ToString())
{
case "nl-NL":
MyProject.Language.Resources.Culture = new System.Globalization.CultureInfo("nl-NL");
break;
case "en-GB":
MyProject.Language.Resources.Culture = new System.Globalization.CultureInfo("en-GB");
break;
default://default english because there can be so many different system language, we rather fallback on english in this case.
MyProject.Language.Resources.Culture = new System.Globalization.CultureInfo("en-GB");
break;
}
}
}
Using it in Angular (convert to JSON)
Now days it is more common to have a framework like Angular in combination with components, so without cshtml. Translations are stored in json files, I am not going to cover how that works, but if you want to convert this to a JSON file, it is pretty easy, I use a T4 template script that converts the Resources file to a json file. I recommend installing T4 editor to read the syntax and use it correctly because you need to do some modifications.
Only 1 thing to note: It is not possible to generate the data, copy it, clean the data and generate it for another language. So you have to copy below code as many times as languages you have and change the entry before '//choose language here'. Currently no time to fix this but probably will update later (if interested).
Path: MyProject.Language/T4/CreateWebshopLocalizationEN.tt
<#@ template debug="false" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="System.Windows.Forms" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Resources" #>
<#@ import namespace="System.Collections" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.ComponentModel.Design" #>
<#@ output extension=".json" #>
<#
var fileNameNl = "../Resources/Resources.resx";
var fileNameEn = "../Resources/Resources.en.resx";
var fileNameDe = "../Resources/Resources.de.resx";
var fileNameTr = "../Resources/Resources.tr.resx";
var fileResultName = "../T4/CreateWebshopLocalizationEN.json";//choose language here
var fileResultPath = Path.Combine(Path.GetDirectoryName(this.Host.ResolvePath("")), "MyProject.Language", fileResultName);
//var fileDestinationPath = "../../MyProject.Web/ClientApp/app/i18n/";
var fileNameDestNl = "nl.json";
var fileNameDestEn = "en.json";
var fileNameDestDe = "de.json";
var fileNameDestTr = "tr.json";
var pathBaseDestination = Directory.GetParent(Directory.GetParent(this.Host.ResolvePath("")).ToString()).ToString();
string[] fileNamesResx = new string[] {fileNameEn }; //choose language here
string[] fileNamesDest = new string[] {fileNameDestEn }; //choose language here
for(int x = 0; x < fileNamesResx.Length; x++)
{
var currentFileNameResx = fileNamesResx[x];
var currentFileNameDest = fileNamesDest[x];
var currentPathResx = Path.Combine(Path.GetDirectoryName(this.Host.ResolvePath("")), "MyProject.Language", currentFileNameResx);
var currentPathDest =pathBaseDestination + "/MyProject.Web/ClientApp/app/i18n/" + currentFileNameDest;
using(var reader = new ResXResourceReader(currentPathResx))
{
reader.UseResXDataNodes = true;
#>
{
<#
foreach(DictionaryEntry entry in reader)
{
var name = entry.Key;
var node = (ResXDataNode)entry.Value;
var value = node.GetValue((ITypeResolutionService) null);
if (!String.IsNullOrEmpty(value.ToString())) value = value.ToString().Replace("\n", "");
if (!String.IsNullOrEmpty(value.ToString())) value = value.ToString().Replace("\r", "");
#>
"<#=name#>": "<#=value#>",
<#
}
#>
"WEBSHOP_LASTELEMENT": "just ignore this, for testing purpose"
}
<#
}
File.Copy(fileResultPath, currentPathDest, true);
}
#>
There you go, you can now use one single resource file for all your projects. This makes it very easy exporting everything to an excl document and let someone translate it and import it again.
I've seen projects implemented using a number of different approaches, each have their merits and drawbacks.
I'd say the resource method you've chosen makes a lot of sense. It would be interesting to see other people's answers too as I often wonder if there's a better way of doing things like this. I've seen numerous resources that all point to the using resources method, including one right here on SO.
I don't think there is a "best way". It really will depend on the technologies and type of application you are building.
Webapps can store the information in the database as other posters have suggested, but I recommend using seperate resource files. That is resource files seperate from your source. Seperate resource files reduces contention for the same files and as your project grows you may find localization will be done seperatly from business logic. (Programmers and Translators).
Microsoft WinForm and WPF gurus recommend using seperate resource assemblies customized to each locale.
WPF's ability to size UI elements to content lowers the layout work required eg: (japanese words are much shorter than english).
If you are considering WPF: I suggest reading this msdn article To be truthful I found the WPF localization tools: msbuild, locbaml, (and maybe an excel spreadsheet) tedious to use, but it does work.
Something only slightly related: A common problem I face is integrating legacy systems that send error messages (usually in english), not error codes. This forces either changes to legacy systems, or mapping backend strings to my own error codes and then to localized strings...yech. Error codes are localizations friend
+1 Database
Forms in your app can even re-translate themselves on the fly if corrections are made to the database.
We used a system where all the controls were mapped in an XML file (one per form) to language resource IDs, but all the IDs were in the database.
Basically, instead of having each control hold the ID (implementing an interface, or using the tag property in VB6), we used the fact that in .NET, the control tree was easily discoverable through reflection. A process when the form loaded would build the XML file if it was missing. The XML file would map the controls to their resource IDs, so this simply needed to be filled in and mapped to the database. This meant that there was no need to change the compiled binary if something was not tagged, or if it needed to be split to another ID (some words in English which might be used as both nouns and verbs might need to translate to two different words in the dictionary and not be re-used, but you might not discover this during initial assignment of IDs). But the fact is that the whole translation process becomes completely independent of your binary (every form has to inherit from a base form which knows how to translate itself and all its controls).
The only ones where the app gets more involved is when a phase with insertion points is used.
The database translation software was your basic CRUD maintenance screen with various workflow options to facilitate going through the missing translations, etc.
I'd go with the multiple resource files. It shouldn't be that hard to configure. In fact I recently answered a similar question on setting a global language based resource files in conjunction with form language resource files.
Localization in Visual Studio 2008
I would consider that the best approach at least for WinForm development.
You can use commercial tools like Sisulizer. It will create satellite assembly for each language. Only thing you should pay attention is not to obfuscate form class names (if you use obfuscator).
I´ve been searching and I´ve found this:
If your using WPF or Silverlight your aproach could be use WPF LocalizationExtension for many reasons.
IT´s Open Source It´s FREE (and will stay free) is in a real stabel state
In a Windows Application you could do someting like this:
public partial class App : Application
{
public App()
{
}
protected override void OnStartup(StartupEventArgs e)
{
Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("de-DE"); ;
Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("de-DE"); ;
FrameworkElement.LanguageProperty.OverrideMetadata(
typeof(FrameworkElement),
new FrameworkPropertyMetadata(
XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
base.OnStartup(e);
}
}
And I think on a Wep Page the aproach could be the same.
Good Luck!
Most opensource projects use GetText for this purpose. I don't know how and if it's ever been used on a .Net project before.
We use a custom provider for multi language support and put all texts in a database table. It works well except we sometimes face caching problems when updating texts in the database without updating the web application.
Standard resource files are easier. However, if you have any language dependent data such as lookup tables then you will have to manage two resource sets.
I haven't done it, but in my next project I would implement a database resource provider. I found how to do it on MSDN:
http://msdn.microsoft.com/en-us/library/aa905797.aspx
I also found this implementation:
DBResource Provider
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