How to Localize validation message (DataAnnotationsValidator) in blazor server side

Question

I am using blazor 3.1 in latest version of VS 2019.

So far, I am able to localize page labels (title, table fields etc.).

On the ListEmployee.razor

Answer 1

Here is my solution for localizing data annotation error messages. I create two resource files, one for fields and another one for error messages.

• DisplayNameResource for localizing fields
• ErrorMessageResource for localizing error messages

In view model class use Display attribute for localizing field name. To specify resource file use ResourceType property on Display attribute:

[Display(Name = "Address", ResourceType = typeof(DisplayNameResource))]

And on validation attributes use ErrorMessageResourceName and ErrorMessageResourceType to specify resource file:

[Required(ErrorMessageResourceName = "RequiredError", ErrorMessageResourceType = typeof(ErrorMessageResource))]

Here is full example:

public class SomeViewModel
{
    [Display(Name = "Address", ResourceType = typeof(DisplayNameResource))]
    [Required(ErrorMessageResourceName = "RequiredError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    [StringLength(256, ErrorMessageResourceName = "MaxLengthError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    public string Address { get; set; }

    [Display(Name = "Phone", ResourceType = typeof(DisplayNameResource))]
    [Required(ErrorMessageResourceName = "RequiredError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    [RegularExpression("^09([0-9]{9})$", ErrorMessageResourceName = "PhoneLengthError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    public string Phone { get; set; }

    [Display(Name = "Password", ResourceType = typeof(DisplayNameResource))]
    [Required(ErrorMessageResourceName = "RequiredError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    [StringLength(50, MinimumLength = 6, ErrorMessageResourceType = typeof(ErrorMessageResource), ErrorMessageResourceName = "MinxMaxLengthError")]
    public string Password { get; set; }

    [Display(Name = "ConfirmPassword", ResourceType = typeof(DisplayNameResource))]
    [Required(ErrorMessageResourceName = "RequiredError", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    [StringLength(50, MinimumLength = 6, ErrorMessageResourceType = typeof(ErrorMessageResource), ErrorMessageResourceName = "MinxMaxLengthError")]
    [Compare("Password", ErrorMessageResourceName = "PasswordConfirmMisMatch", ErrorMessageResourceType = typeof(ErrorMessageResource))]
    public string ConfirmPassword { get; set; }
}

Error message for MaxLengthError is {0} cannot be longer than {1} character, so {0} will be replaced with localized filed name and {1} will be replaced with the 256 you specified on attribute [StringLength(256,...

Answer 2

This has been asked before:

How to add ViewModel localization to Blazor?

I suggested that using FluentValidation would be a better approach. Here is a link to my Github repo that demonstrates how it could work:

https://github.com/conficient/BlazorValidationLocalization

Answer 3

I did not tried this out!

In the offical docs of asp.net core there is section how to localize DataAnnotations Maybe you find some clues there.