ASP.NET Core

Multi-lingual support for DataAnnotations used for parameter names, input validation messages, etc.

Page creation date :

environment

ASP.NET Core
  • 5.0 MVC

premise

This Tips is written as understanding the following tips:

Also, if you are creating a new project, you must have added the following files and code based on tips above.

  • Create a SharedResource.resx (+en, es) file. (The contents may be empty.)
  • Create a SharedResource.cs file
  • Add localization code to Startup.ConfigureServices
  • Add localization code to Startup.Configure

Startup .cs Fixes

Because additional multilingual settings related to DataAnnotations are required, Startup.ConfigureServices modify the method as follows:

public void ConfigureServices(IServiceCollection services)
{
  services.AddControllersWithViews();

  services.AddMvc()
    // ローカライズに必要。Resx ファイルのフォルダパスを指定
    .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix, opts => { opts.ResourcesPath = "Resources"; })
    // DataAnnotations のローカライズに必要 (追加)
    .AddDataAnnotationsLocalization(options =>
     {
       // DataAnnotation を使ったときのメッセージは SharedResource に集約する
       options.DataAnnotationLocalizerProvider = (type, factory) => factory.Create(typeof(SharedResource));
     });
}

Modeling for input

Create a model to bind to the input screen. In this sample, we have created a number of properties to accommodate various input controls. If you're having trouble creating, you can just create two.

Create a UserViewModel .cs in the Models folder.

The code should look like this: The namespace should be appropriate. The attributes you set are not very relevant to multiple languages because they are only assigned to them. Multilingual support will be done later.

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace LocalizationDataAnnotation.Models
{
  public class UserViewModel
  {
    [Required]
    [Display(Name = "ID (半角英数字)")]
    [StringLength(20)]
    [RegularExpression(@"^[0-9a-zA-Z]*$")]
    public string ID { get; set; }

    [StringLength(50)]
    public string Name { get; set; }

    [StringLength(50, MinimumLength = 8)]
    [DataType(DataType.Password)]
    [RegularExpression(@"^[0-9a-zA-Z]*$", ErrorMessage = "Password")]
    public string Password { get; set; }

    // 省略
  }

  // 省略
}

Create an action

Create actions in to display the user's registration screen and perform registration HomeController actions.

Creating screens and actions is not the main subject of this Tips, so it is appropriate. In addition, the actual registration process is not performed.

// 初期コードは省略

namespace LocalizationDataAnnotation.Controllers
{
  public class HomeController : Controller
  {
    // 初期コードは省略

    public IActionResult Create()
    {
      return View();
    }

    [HttpPost]
    public IActionResult Create(UserViewModel model)
    {
      // エラーなら差し戻し
      if (ModelState.IsValid == false) return View(model);

      // 正常に登録できた場合は Index に戻る
      return RedirectToAction(nameof(Index));
    }
  }
}

Link to user registration screen

Create a link to the user registration screen in Views\Home\Index.cshtml. You can write anything as long as you can have a screen transition.

asp-route-culture The attribute opens the page in the specified language.

<!-- 初期コード省略 -->

<ul>
  <li><a asp-action="Create">Create</a></li>
  <li><a asp-action="Create" asp-route-culture="ja">Create (ja)</a></li>
  <li><a asp-action="Create" asp-route-culture="en">Create (en)</a></li>
  <li><a asp-action="Create" asp-route-culture="es">Create (es)</a></li>
</ul>

Create a user registration screen

Create Right-click the action and select Add View.

Select Razor View.

Make the template "Create" and the model class "UserViewModel". If you're using the sample UserViewModel code, I've also included comments in the code. If you put certain attributes in a property, you will get an error when generating code in scaffolding. Please temporarily comment out before creating a view.

If you really get an error when you create it, create an empty Razor view and include the following code:

@model LocalizationDataAnnotation.Models.UserViewModel
@using System.Globalization;
@{
  ViewData["Title"] = "Create";
}

<h1>Create</h1>

<h4>UserViewModel</h4>
<hr />
<div class="row">
  <div class="col-md-4">
    <form asp-action="Create">
      <div asp-validation-summary="ModelOnly" class="text-danger"></div>
      <div class="form-group">
        <label asp-for="ID" class="control-label"></label>
        <input asp-for="ID" class="form-control" />
        <span asp-validation-for="ID" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Name" class="control-label"></label>
        <input asp-for="Name" class="form-control" />
        <span asp-validation-for="Name" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Password" class="control-label"></label>
        <input asp-for="Password" class="form-control" />
        <span asp-validation-for="Password" class="text-danger"></span>
      </div>

      <!-- 省略 -->

      <div class="form-group">
        <input type="submit" value="Create" class="btn btn-primary" asp-route-culture="@CultureInfo.CurrentCulture.Name" />
      </div>
    </form>
  </div>
</div>

<div>
  <a asp-action="Index">Back to List</a>
</div>

@section Scripts {
  @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

For now, as a preparatory stage, you can build the code so far successfully, and try to see and run the screen correctly.

Multilingual text registration for DataAnnotations

All properties are long to explain, so we'll ID talk to and for . Name Other properties are multilingual in a similar way, so try them out.

The following texts are available in multiple languages here.

Multi-lingual text keys
Id parameter display name ID_DisplayName
Error message when ID not entered Validate_Required
Error message when id input character exceeds 20 characters Validate_StringLength
Error message when id is typed with nonnumeric characters Validate_Alphanumeric
Name parameter display name Name_DisplayName
Error message when name has more than 50 characters entered Validate_StringLength

Validate_XXXXX be universal. There is no key naming convention, so you can freely attach it.

Using these keys as the basis, SharedResource.resx we will fill in the SharedResource.en.resx translated text into , SharedResource.es.resx , .

SharedResource.resx

Name value
Validate_Required "{0}" is required.
Validate_StringLength You can enter up to "{1}" in "{0}".
Validate_Alphanumeric {0} can only be alphanumeric.
ID_DisplayName ID (alphanumeric)
Name_DisplayName identity

SharedResource.en.resx

Name value
Validate_Required "{0}" is a required input.
Validate_StringLength The maximum number of characters that can be entered in "{0}" is "{1}".
Validate_Alphanumeric Only alphanumeric characters can be entered for "{0}".
ID_DisplayName ID (alphanumeric characters)
Name_DisplayName Full name

SharedResource.es.resx

Name value
Validate_Required "{0}" es una entrada obligatoria.
Validate_StringLength El número máximo de caracteres que se pueden ingresar en "{0}" es "{1}".
Validate_Alphanumeric Solo se pueden ingresar caracteres alfanuméricos para "{0}".
ID_DisplayName ID (caracteres alfanuméricos)
Name_DisplayName Nombre completo

Input validation error messages replace parameter names and numbers with {0} and {1}. Let's use it positively.

Multi-lingual application to DataAnnotations

All multilingual settings are applied to the attributes of the model (DataAnnotations).

To apply it to the display name of the parameter, Display attach and specify a Name sharedResource.resx key in the property.

To apply to error messages during input validation, specify a ErrorMessage sharedResource.resx key in the property of each validation attribute.

public class UserViewModel
{
  [Required(ErrorMessage = "Validate_Required")]
  [Display(Name = "ID_DisplayName")]
  [StringLength(20, ErrorMessage = "Validate_StringLength")]
  [RegularExpression(@"^[0-9a-zA-Z]*$", ErrorMessage = "Validate_Alphanumeric")]
  public string ID { get; set; }

  [Display(Name = "Name_DisplayName")]
  [StringLength(50, ErrorMessage = "Validate_StringLength")]
  public string Name { get; set; }

  // 省略
}

This completes the setup. After that, run it to see how it works.

By the way, the number of input characters is limited by the attribute of the input maxlength tag. If you want to see the message, you need to remove the restrictions, such as in the developer tools of your Web browser.

By the way, there are some messages displayed when registering your age, date, etc. empty. This is a message that is set up on the framework side, but another Tips will show you how to support it in multiple languages.

For all codes

This Tips contains only some properties, but the sample code covers all html5-enabled input fields. If you want to check, please refer to the link above the page.

Listed in part below

UserViewModel.cs

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace LocalizationDataAnnotation.Models
{
  public class UserViewModel
  {
    [Required(ErrorMessage = "Validate_Required")]
    [Display(Name = "ID_DisplayName")]
    [StringLength(20, ErrorMessage = "Validate_StringLength")]
    [RegularExpression(@"^[0-9a-zA-Z]*$", ErrorMessage = "Validate_Alphanumeric")]
    public string ID { get; set; }

    [Display(Name = "Name_DisplayName")]
    [StringLength(50, ErrorMessage = "Validate_StringLength")]
    public string Name { get; set; }

    [Display(Name = "Password_DisplayName")]
    [StringLength(50, MinimumLength = 8, ErrorMessage = "Validate_StringLengthRange")]
    [DataType(DataType.Password)]
    [RegularExpression(@"^[0-9a-zA-Z]*$", ErrorMessage = "Validate_Alphanumeric")]
    public string Password { get; set; }

    [Display(Name = "ConfirmPassword_DisplayName")]
    [StringLength(50, MinimumLength = 8, ErrorMessage = "Validate_StringLengthRange")]
    [DataType(DataType.Password)]
    [Compare(nameof(Password), ErrorMessage = "Validate_Compare")]
    public string ConfirmPassword { get; set; }

    [Display(Name = "Email_DisplayName")]
    [EmailAddress(ErrorMessage = "Validate_EmailAddress")]
    [DataType(DataType.EmailAddress)] // スキャフォールディングするときはコメントアウトする
    public string Email { get; set; }

    [Display(Name = "Age_DisplayName")]
    [Required(ErrorMessage = "Validate_Required")]
    [Range(0, 150, ErrorMessage = "Validate_Range")]
    public int Age { get; set; }

    [Display(Name = "Gender_DisplayName")]
    [Required(ErrorMessage = "Validate_Required")]
    [EnumDataType(typeof(GenderType))]
    public GenderType Gender { get; set; }

    [Display(Name = "Birthday_DisplayName")]
    [DataType(DataType.Date)]
    public DateTime Birthday { get; set; }

    [Display(Name = "Phone_DisplayName")]
    [Phone(ErrorMessage = "Validate_Phone")]
    [DataType(DataType.PhoneNumber)] // スキャフォールディングするときはコメントアウトする
    public string Phone { get; set; }

    [Display(Name = "PostalCode_DisplayName")]
    [DataType(DataType.PostalCode)]
    public string PostalCode { get; set; }

    [Display(Name = "CreditCard_DisplayName")]
    [CreditCard(ErrorMessage = "Validate_CreditCard")]
    [DataType(DataType.CreditCard)] // スキャフォールディングするときはコメントアウトする
    public string CreditCard { get; set; }

    [Display(Name = "Money_DisplayName")]
    [DataType(DataType.Currency)]
    public decimal Money { get; set; }

    [Display(Name = "StartDateTime_DisplayName")]
    [DataType(DataType.DateTime)]
    public DateTime StartDateTime { get; set; }

    [Display(Name = "WakeUpTime_DisplayName")]
    [DataType(DataType.Time)]
    public TimeSpan WakeUpTime { get; set; }

    [Display(Name = "Homepage_DisplayName")]
    [Url(ErrorMessage = "Validate_Url")]
    [DataType(DataType.Url)] // スキャフォールディングするときはコメントアウトする
    public string Homepage { get; set; }

    [Display(Name = "MyImage_DisplayName")]
    [Url(ErrorMessage = "Validate_Url")]
    [DataType(DataType.ImageUrl)] // スキャフォールディングするときはコメントアウトする
    public string MyImage { get; set; }

    [Display(Name = "MyColor_DisplayName")]
    public string MyColor { get; set; }

    [Display(Name = "WorkingDays_DisplayName")]
    [MaxLength(5, ErrorMessage = "Validate_MaxLength")]
    [EnumDataType(typeof(DayOfWeek))]
    public DayOfWeek[] WorkingDays { get; set; }

    [Display(Name = "VacationDay_DisplayName")]
    [MinLength(3, ErrorMessage = "Validate_MinLength")]
    [EnumDataType(typeof(DayOfWeek))]
    public DayOfWeek[] VacationDay { get; set; }

    [Display(Name = "Comment_DisplayName")]
    [StringLength(200, ErrorMessage = "Validate_StringLength")]
    [DataType(DataType.MultilineText)]
    public string Comment { get; set; }

    [Display(Name = "FileName_DisplayName")]
    [FileExtensions(Extensions = "png", ErrorMessage = "Validate_FileExtensions")]
    public string FileName { get; set; }

    [Display(Name = "UploadFile_DisplayName")]
    [DataType(DataType.Upload)]
    public List<IFormFile> UploadFile { get; set; }

    [Display(Name = "Month_DisplayName")]
    public DateTime Month { get; set; }

    [Display(Name = "Search_DisplayName")]
    public string Search { get; set; }

    [Display(Name = "Range_DisplayName")]
    [Range(10, 100, ErrorMessage = "Validate_Range")]
    public int Range { get; set; }

    [Display(Name = "Week_DisplayName")]
    public string Week { get; set; }

    [Display(Name = "IsAccepted_DisplayName")]
    [Required(ErrorMessage = "Validate_Required")]
    public bool IsAccepted { get; set; }
  }

  public enum GenderType
  {
    None,
    Man,
    Woman,
    Other,
  }
}

HomeController.cs

using LocalizationDataAnnotation.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

namespace LocalizationDataAnnotation.Controllers
{
  public class HomeController : Controller
  {
    private readonly ILogger<HomeController> _logger;

    public HomeController(ILogger<HomeController> logger)
    {
      _logger = logger;
    }

    public IActionResult Index()
    {
      return View();
    }

    public IActionResult Privacy()
    {
      return View();
    }

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error()
    {
      return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
    }

    public IActionResult Create()
    {
      SetDayOfWeeksViewData();
      return View();
    }

    [HttpPost]
    public IActionResult Create(UserViewModel model)
    {
      SetDayOfWeeksViewData();

      // エラーなら差し戻し
      if (ModelState.IsValid == false) return View(model);

      // 正常に登録できた場合は Index に戻る
      return RedirectToAction(nameof(Index));
    }

    /// <summary>曜日の一覧を ViewData に設定します。</summary>
    private void SetDayOfWeeksViewData()
      => ViewData["DayOfWeeks"] = ((DayOfWeek[])Enum.GetValues(typeof(DayOfWeek))).Select(x => new SelectListItem(x.ToString(), ((int)x).ToString()));
  }
}

Create.cshtml

@model LocalizationDataAnnotation.Models.UserViewModel
@using System.Globalization;
@{
  ViewData["Title"] = "Create";
}

<h1>Create</h1>

<h4>UserViewModel</h4>
<hr />
<div class="row">
  <div class="col-md-4">
    <form asp-action="Create" enctype="multipart/form-data" >
      <div asp-validation-summary="ModelOnly" class="text-danger"></div>
      <div class="form-group">
        <label asp-for="ID" class="control-label"></label>
        <input asp-for="ID" class="form-control" />
        <span asp-validation-for="ID" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Name" class="control-label"></label>
        <input asp-for="Name" class="form-control" />
        <span asp-validation-for="Name" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Password" class="control-label"></label>
        <input asp-for="Password" class="form-control" />
        <span asp-validation-for="Password" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="ConfirmPassword" class="control-label"></label>
        <input asp-for="ConfirmPassword" class="form-control" />
        <span asp-validation-for="ConfirmPassword" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Email" class="control-label"></label>
        <input asp-for="Email" class="form-control" />
        <span asp-validation-for="Email" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Age" class="control-label"></label>
        <input asp-for="Age" class="form-control" />
        <span asp-validation-for="Age" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Gender"></label>
        <div>
          <label><input type="radio" asp-for="Gender" value="@(GenderType.None)" />@(GenderType.None)</label>
          <label><input type="radio" asp-for="Gender" value="@(GenderType.Man)" />@(GenderType.Man)</label>
          <label><input type="radio" asp-for="Gender" value="@(GenderType.Woman)" />@(GenderType.Woman)</label>
        </div>
        <span asp-validation-for="Gender" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Birthday" class="control-label"></label>
        <input asp-for="Birthday" class="form-control" />
        <span asp-validation-for="Birthday" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Phone" class="control-label"></label>
        <input asp-for="Phone" class="form-control" />
        <span asp-validation-for="Phone" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="PostalCode" class="control-label"></label>
        <input asp-for="PostalCode" class="form-control" />
        <span asp-validation-for="PostalCode" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="CreditCard" class="control-label"></label>
        <input asp-for="CreditCard" class="form-control" />
        <span asp-validation-for="CreditCard" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Money" class="control-label"></label>
        <input asp-for="Money" class="form-control" />
        <span asp-validation-for="Money" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="StartDateTime" class="control-label"></label>
        <input asp-for="StartDateTime" class="form-control" />
        <span asp-validation-for="StartDateTime" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="WakeUpTime" class="control-label"></label>
        <input asp-for="WakeUpTime" class="form-control" />
        <span asp-validation-for="WakeUpTime" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Homepage" class="control-label"></label>
        <input asp-for="Homepage" class="form-control" />
        <span asp-validation-for="Homepage" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="MyImage" class="control-label"></label>
        <input asp-for="MyImage" class="form-control" />
        <span asp-validation-for="MyImage" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="MyColor" class="control-label"></label>
        <input asp-for="MyColor" class="form-control" type="color" />
        <span asp-validation-for="MyColor" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="WorkingDays" class="control-label"></label>
        <select asp-for="WorkingDays" class="form-control" asp-items="@((IEnumerable<SelectListItem>)ViewData["DayOfWeeks"])" multiple></select>
        <span asp-validation-for="WorkingDays" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="VacationDay" class="control-label"></label>
        <select asp-for="VacationDay" class="form-control" asp-items="@((IEnumerable<SelectListItem>)ViewData["DayOfWeeks"])" multiple></select>
        <span asp-validation-for="VacationDay" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Comment" class="control-label"></label>
        <textarea asp-for="Comment" class="form-control"></textarea>
        <span asp-validation-for="Comment" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="FileName" class="control-label"></label>
        <input asp-for="FileName" class="form-control" />
        <span asp-validation-for="FileName" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="UploadFile" class="control-label"></label>
        <input asp-for="UploadFile" type="file" multiple />
        <span asp-validation-for="UploadFile" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Month" class="control-label"></label>
        <input asp-for="Month" class="form-control" type="month" />
        <span asp-validation-for="Month" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Search" class="control-label"></label>
        <input asp-for="Search" class="form-control" type="search" />
        <span asp-validation-for="Search" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Range" class="control-label"></label>
        <input asp-for="Range" class="form-control" type="range" min="10" max="100" />
        <span asp-validation-for="Range" class="text-danger"></span>
      </div>
      <div class="form-group">
        <label asp-for="Week" class="control-label"></label>
        <input asp-for="Week" class="form-control" type="week" />
        <span asp-validation-for="Week" class="text-danger"></span>
      </div>
      <div class="form-group form-check">
        <label class="form-check-label">
          <input class="form-check-input" asp-for="IsAccepted" /> @Html.DisplayNameFor(model => model.IsAccepted)
        </label>
      </div>
      <div class="form-group">
        <input type="submit" value="Create" class="btn btn-primary" asp-route-culture="@CultureInfo.CurrentCulture.Name" />
      </div>
    </form>
  </div>
</div>

<div>
  <a asp-action="Index">Back to List</a>
</div>

@section Scripts {
  @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}
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