Blazor Add validation error/message for field

[omuleanu]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

is it possible (is there plans to implement) to add a validation error like in MVC AddModelError(key, errorMessage) ?

for now I have temporary workaround which looks like this:

public class CustomValid : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        if (value is null) return true;
        
        ErrorMessage = (string)value;
        return false;
    }
}

ViewModel:

[CustomValid]
public string Vld1 { get; set; }

save code:

input.Vld1 = input.Name == "Foo" ? "Name not unique" : null;
if (!editContext.Validate()) ...

Describe the solution you'd like

EditContext.AddFieldError(fieldName, errorMessage)

Additional context

No response

[mkArtakMSFT]

Thanks for contacting us. This is already supported and you can learn how to do it from https://docs.microsoft.com/en-us/aspnet/core/blazor/forms-validation?view=aspnetcore-6.0#basic-validation
Please look for ValidationMessageStore API.

[omuleanu]

@mkArtakMSFT it's a lot more complicated comparing to MVC's ModelState.AddModelError ,
and you can't call await inside HandleValidationRequested

is this part important:

    public void Dispose()
    {
        if (editContext is not null)
        {
            editContext.OnValidationRequested -= HandleValidationRequested;
        }
    }

wouldn't dispose, dispose the editContext which is field in the component ?