The ForEvolve.AspNetCore.Localization package allows you to enable localization of Asp.Net Core 2.1+ applications in one line of code. Moreover, it translates System.ComponentModel.DataAnnotations.ValidationAttributes automagically, without the need to specify any string or error message (like the [Required] attribute).

• English (en) original error messages modified by Carl-Hugo Marcotte
• French (fr) original translation by Carl-Hugo Marcotte
• Hebrew (he) thanks to aboyaniv
• Portuguese (pt) thanks to Matheus Avi (Same as pt-BR, needs to be checked)
• Brazilian portuguese (pt-BR) thanks to Matheus Avi
• Spanish (es) thanks to Oswaldo Diaz
• Norwegian (bokmål) (nb) thanks to Petter Hoel (If you are using nb-NO it should default to nb)
• Norwegian (bokmål) (no) thanks to Petter Hoel (Same as nb)
• Chinese (zh) thanks to Jay Skyworker (Same as zh-TW, needs to be checked)
• Chinese Traditional (zh-Hant) thanks to Jay Skyworker (Same as zh-TW, needs to be checked)
• Chinese Traditional, Taiwan (zh-TW) thanks to Jay Skyworker
• Polish (pl) thanks to Denis Pujdak

• CompareAttribute
• EmailAddressAttribute
• RequiredAttribute
• CreditCardAttribute
• FileExtensionsAttribute
• MaxLengthAttribute
• MinLengthAttribute
• PhoneAttribute
• RangeAttribute
• RegularExpressionAttribute
• UrlAttribute
• StringLengthAttribute (see StringLengthLocalizationValidationAttributeAdapter.cs)

You can also create and register your own adapters and attributes like normal.

The packages follows semantic versioning and uses Nerdbank.GitVersioning to automatically version packages based on git commits/hashes.

You can:

Install-Package ForEvolve.AspNetCore.Localization

or

dotnet add package ForEvolve.AspNetCore.Localization

or take a look at https://www.nuget.org/packages/ForEvolve.AspNetCore.Localization/.

PR builds are pushed to feedz.io before getting released to NuGet, thanks to their Open Source subscription.

The NuGet v3 URL is: https://f.feedz.io/forevolve/localization/nuget/index.json

To enable localization for everything, including data annotation, you need to:

1. Add the ForEvolve.AspNetCore.Localization NuGet package to your project.
2. In Startup.cs, AddForEvolveLocalization() and optionally UseRequestLocalization() (see below).
3. Run your application

public void ConfigureServices(IServiceCollection services)
{
    // MVC (2.1)
    services
        .AddMvc()
        .AddForEvolveLocalization()
    ;

    // MVC (3+)
    services
        .AddRazorPages() // or other part of MVC that returns an IMvcBuilder
        .AddForEvolveLocalization()
    ;
}

public void Configure(IApplicationBuilder app)
{
    // (optional)
    // Adds the Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware to automatically
    // set culture information for requests based on information provided by the client.
    app.UseRequestLocalization();

    //...
}

As you can see, it took only one line of code to enable localization, and another line to automatically set the culture information for requests using RequestLocalizationMiddleware.

IMvcBuilder.AddForEvolveLocalization(); adds all necessary services to the DI container. It calls IServiceCollection.AddLocalization(...), set the default ResourcesPath to "Resources", registers the ILocalizationValidationMetadataProvider (which does the validation attributes localization magic), and calls both IMvcBuilder.AddViewLocalization() and IMvcBuilder.AddDataAnnotationsLocalization().

If you don't want IMvcBuilder.AddViewLocalization() or IMvcBuilder.AddDataAnnotationsLocalization() to be called, you can opt-out by using an overload of IMvcBuilderAddForEvolveLocalization(), like that:

services
    .AddRazorPages() // or other part of MVC that returns an IMvcBuilder
    .AddForEvolveLocalization(
        enableViewLocalization: false,
        enableDataAnnotationsLocalization: false
    )
;

If you want to change any Asp.Net-related options, you can Configure them or implements IConfigureOptions<TOptions> classes as you would normally do. In 3.0 all options has been removed, so no need to learn how the library work, you must use Asp.Net options directly. See the Change log for more info.

If you built custom ILocalizationValidationAttributeAdapter, just register them with the DI container, like:

services.AddSingleton<ILocalizationValidationAttributeAdapter, MyAdapter>()

For any other use-case that I may have forgotten, please open an issue.

Since I only know French and English, I can't translate messages into more languages, so contributions are very welcome.

I built a small tool to help find the culture-neutral and culture-specifics CultureInfo about a language; please make sure that your translation covers the culture-neutral CultureInfo before creating a culture-specific one.

• CultureInfo Browser.

How to submit a new translation:

1. Fork the repo
2. Create a resource file for the language you want to translate error messages into.
3. Translate it (obviously)
4. Add the new language to the _supportedCultures array in SupportedCulturesCollection.cs.
5. Add the new language to the Supported languages section of the README.md file with a "thanks to you" attribution and a link.
6. Open a pull request

Since I don't speak all languages, I cannot validate those that I don't know (except maybe by using Google Translate), so it's up to you to makes things right! (or PR corrections)

I will do my best to integrates PR as fast as possible.

If you look under src/ForEvolve.AspNetCore.Localization/Resources/, you will find DataAnnotationSharedResource.resx and DataAnnotationSharedResource.{lang}.resx files. You can copy any one of those and translate the values.

If you want to create a culture-specific translation, example: fr-CA, please make sure that there is an fr translation (neutral culture) first which will be the default for that language.

Example:

• First we need a DataAnnotationSharedResource.fr.resx file (already there).
• Then we could add DataAnnotationSharedResource.fr-CA.resx, DataAnnotationSharedResource.fr-FR.resx, etc.

I modified default error messages a little to make them more linear. Sometimes it was written The field {0} ... and sometimes it was The {0} field .... I decided to normalize messages to The {0} field ....

I am open to suggestion if you think this makes no sense. English is only my secondary language.

Error messages source (if you want the original error messages): corefx/src/System.ComponentModel.Annotations/src/Resources/Strings.resx

I created this project because I did not want to code something similar to this every single time I start a new Asp.Net Core application. I did not want to write an error message on every ValidationAttribute either (which seems to be the official solution).

To be honest, I was a little disappointed to see how hard it is to localize Asp.Net Core validation attributes. This should be trivial.

Don't get me wrong here; I don't want to criticize the design made by the team that built that system. I can only assume that there are some good reasons behind these design choices (technical or not).

That said, the other parts of the localization pipeline of Asp.Net Core are pretty neat with IStringLocalizer, IHtmlLocalizer and IViewLocalizer.

If you have ideas, requests or find bugs, please open an issue. If you want to contributes some code, other than translating error messages, please open an issue first so you don't waste your time.

For more information, please read Contributing to ForEvolve open source projects.

Also, please read the Contributor Covenant Code of Conduct that applies to all ForEvolve repositories.

• Remove the need to call IServiceCollection.AddForEvolveLocalization() (see #27)
• Rename IMvcBuilder.AddForEvolveMvcLocalization() to IMvcBuilder.AddForEvolveLocalization()
• Leverage the options patterns to configure Asp.Net instead of custom options. Due to that, ForEvolveLocalizationOptions and ForEvolveMvcDefaultLocalizationAdapterOptions has been deleted.
• Internally leveraging DI more to simplify the initialization process (no more newing volatile dependencies).
• IApplicationBuilder.UseForEvolveRequestLocalization() is now obsolete, use IApplicationBuilder.UseRequestLocalization() instead.
• Use Nerdbank.GitVersioning to manage versions automagically.
• Move builds from Azure DevOps to GitHub Actions so PR can be made to the CI/CD pipeline.
• You can now use ISupportedCulturesCollection to access the list of supported CultureInfo.

• Add Polish (pl)

• Add Chinese (zh)
• Add Chinese (Traditional) (zh-Hant)
• Add Chinese (Traditional, Taiwan) (zh-TW)

• Update MetadataProvider so DataTypeAttribute gets the translation; Fix #21
• Add functional tests that are covering most scenarios, related to error messages; closing #1
• Add functional tests that are covering French translation; related to #5. This should ensure that further breaking changes in the Asp.Net Core repo would be detected automatically by the CI pipeline.

• User-specified ErrorMessage on DataTypeAttribute might (will most likely) get overridden by ForEvolve.AspNetCore.Localization.

• Add Norwegian (bokmål) (nb) and Norwegian (bokmål) (no)

• Add Spanish (es)

• Add Portuguese (pt) and Brazilian portuguese (pt-BR)

• Initial French (fr) and English (en)
• Contributed Hebrew (he)