DataAnnotations Localization does not localize the pre-formatted validation error messages

[natilivni]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When configuring DataAnnotation localization in the following manner:

 builder.AddDataAnnotationsLocalization(options =>
 options.DataAnnotationLocalizerProvider = (type, factory) =>
 factory.Create(typeof(SharedResource)))
);

The "out of the box" attributes only attempted to localize AFTER the error message has been formatted.

So if I have a class such as:

public class MyClass 
{
 [Required]
 public string MyProperty { get; set; }
}

And I validate the class under a seperate culture, the following mapping will not work:

The {0} field is required. ----> El campo {0} es obligatorio.

However, the following mapping will work:

The MyProperty field is required. ----> El campo MyProperty es obligatorio.

This is because of the following code in DataAnnotationsModelValidator:

var result = Attribute.GetValidationResult(validationContext.Model, context);
 if (result != ValidationResult.Success)
 {
 string errorMessage;
 if (_stringLocalizer != null &&
 !string.IsNullOrEmpty(Attribute.ErrorMessage) &&
 string.IsNullOrEmpty(Attribute.ErrorMessageResourceName) &&
 Attribute.ErrorMessageResourceType == null)
 {
 errorMessage = GetErrorMessage(validationContext) ?? result.ErrorMessage;
 }
 else
 {
 errorMessage = result.ErrorMessage;
 }

Since Attribute.GetValidationResult(validationContext.Model, context) returns a formatted string and the `GetErrorMessage runs after this string is formated, we can never localize the generic error message.

Is there a plan to fix this or is there a work-around for such a scenario?

Thanks.

Expected Behavior

AddDataAnnotationsLocalization should allow mapping of the template string before it is formatted.

Steps To Reproduce

see above.

Exceptions (if any)

No response

.NET Version

net5.0

Anything else?

No response

[mkArtakMSFT]

Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project (ideally a GitHub repo) that illustrates the problem.

Hi @natilivni. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[natilivni]

Hi. The problem is actually broader than I thought, the [Required] attribute does not even attempt to localize the error message at all. Please see the unit tests in this repo:

https://github.com/natilivni/dataannotationsexample/blob/main/DataAnnotationsExample/TestProject1/UnitTest1.cs

There are two unit tests. They both will fail to generate a Spanish error message in spite of the resource file being configured correctly. If seems like the localizer is only used if an explicit error message is set on a validation attribute.

Tagging subscribers to this area: @ajcvickers, @bricelam, @roji
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When configuring DataAnnotation localization in the following manner:

 builder.AddDataAnnotationsLocalization(options =>
 options.DataAnnotationLocalizerProvider = (type, factory) =>
 factory.Create(typeof(SharedResource)))
);

The "out of the box" attributes only attempted to localize AFTER the error message has been formatted.

So if I have a class such as:

public class MyClass 
{
 [Required]
 public string MyProperty { get; set; }
}

And I validate the class under a seperate culture, the following mapping will not work:

The {0} field is required. ----> El campo {0} es obligatorio.

However, the following mapping will work:

The MyProperty field is required. ----> El campo MyProperty es obligatorio.

This is because of the following code in DataAnnotationsModelValidator:

var result = Attribute.GetValidationResult(validationContext.Model, context);
 if (result != ValidationResult.Success)
 {
 string errorMessage;
 if (_stringLocalizer != null &&
 !string.IsNullOrEmpty(Attribute.ErrorMessage) &&
 string.IsNullOrEmpty(Attribute.ErrorMessageResourceName) &&
 Attribute.ErrorMessageResourceType == null)
 {
 errorMessage = GetErrorMessage(validationContext) ?? result.ErrorMessage;
 }
 else
 {
 errorMessage = result.ErrorMessage;
 }

Since Attribute.GetValidationResult(validationContext.Model, context) returns a formatted string and the `GetErrorMessage runs after this string is formated, we can never localize the generic error message.

Is there a plan to fix this or is there a work-around for such a scenario?

Thanks.

Expected Behavior

AddDataAnnotationsLocalization should allow mapping of the template string before it is formatted.

Steps To Reproduce

see above.

Exceptions (if any)

No response

.NET Version

net5.0

Anything else?

No response

Author:	natilivni
Assignees:	-
Labels:	area-System.ComponentModel.DataAnnotations
Milestone:	-