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Localizing Valdiation Errors

By Ziya Mollamahmut

All validation errors are localized by XLocalizer with the default setup, so no additional steps required to localize validation errors. What is more, there is no need to provide an error message inside valdiation attributes! All attributes will have an error message assigned and localized by XLocalizer by default.

Below are sample attributes with the default error messages they produce:

// "The {0} field is required."
[Required]

// "The field {0} must be a string with a maximum length of {1}."
[StringLength(10)]

// "The field {0} must be a string with a minimum length of {2} and a maximum length of {1}."
[StringLength(10, MinimumLength=3)]

// "The field {0} must be between {1} and {2}."
[Range(3, 10)]

// "The field {0} must be a string or array type with a minimum length of '{1}'."
[MinLength(3)]

// "The field {0} must be a string or array type with a maximum length of '{1}'."
[MaxLength(10)]

// "'{0}' and '{1}' do not match."
[Compare("other_field")]

// "The field {0} must match the regular expression '{1}'."
[RegularExpression("regex_pattern")]

// "The {0} field is not a valid credit card number."
[CreditCard]

// "{0} is not valid."
[CustomValdiation]

// "The {0} field is not a valid e-mail address."
[EmailAddress]

// "The {0} field only accepts files with the following extensions: {1}"
[FileExtensions]

// "The {0} field is not a valid phone number."
[Phone]

// "The {0} field is not a valid fully-qualified http, https, or ftp URL."
[Url]

Customize validation errors

Validation errors can be customized by providing a new object of type XLocalizer.ErrorMessages.ValidationErrors into XLocalizerOptions in startup file.

services.AddRazorPages()
        .AddXLocalizer<...>(ops =>
        {
            // ...
            ops.ValidationErrors = new ValidationErrors 
            {
                RequiredAttribute_ValidationError = "The {0} field is required.",
                CompareAttribute_MustMatch = "'{0}' and '{1}' do not match.",
                StringLengthAttribute_ValidationError = "The field {0} must be a string with a maximum length of {1}.",
                // ...
            };
        });

Same way we can provide the default validiation errors in a different culture other than "en".

Customize via json

See Setup XLocalizer via JSON Settings.

Next: Model binding errors