如何本地化 ASP.NET Core (v2.2) 中验证属性的标准错误消息?例如,[必填]属性有此错误消息“The xxx field is required.”; [EmailAddress] 有“xxx 字段不是有效的电子邮件地址。”; [比较]有“'xxx'和'yyy'不匹配。”等等。在我们的项目中,我们不使用英语,我想找到一种方法来翻译标准错误消息,而不是直接将它们写入每个数据模型类的每个属性中
如果您只想本地化错误消息而不是构建多语言站点,您可以尝试以下操作:(消息字符串可能是您的语言。)
IValidationMetadataProvider
: public class MyModelMetadataProvider : IValidationMetadataProvider
{
public void CreateValidationMetadata(ValidationMetadataProviderContext context)
{
if (context == null)
{
throw new ArgumentNullException();
}
var validators = context.ValidationMetadata.ValidatorMetadata;
// add [Required] for value-types (int/DateTime etc)
// to set ErrorMessage before asp.net does it
var theType = context.Key.ModelType;
var underlyingType = Nullable.GetUnderlyingType(theType);
if (theType.IsValueType &&
underlyingType == null && // not nullable type
validators.Where(m => m.GetType() == typeof(RequiredAttribute)).Count() == 0)
{
validators.Add(new RequiredAttribute());
}
foreach (var obj in validators)
{
if (!(obj is ValidationAttribute attribute))
{
continue;
}
fillErrorMessage<RequiredAttribute>(attribute,
"You must fill in '{0}'.");
fillErrorMessage<MinLengthAttribute>(attribute,
"Min length of '{0}' is {1}.");
fillErrorMessage<MaxLengthAttribute>(attribute,
"Max length of '{0}' is {1}.");
fillErrorMessage<EmailAddressAttribute>(attribute,
"Invalid email address.", true);
// other attributes like RangeAttribute, CompareAttribute, etc
}
}
private void fillErrorMessage<T>(object attribute, string errorMessage,
bool forceOverriding = false)
where T : ValidationAttribute
{
if (attribute is T validationAttribute)
{
if (forceOverriding ||
(validationAttribute.ErrorMessage == null
&& validationAttribute.ErrorMessageResourceName == null))
{
validationAttribute.ErrorMessage = errorMessage;
}
}
}
}
Startup.cs
中添加一些行: public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews()
.AddMvcOptions(m => {
m.ModelMetadataDetailsProviders.Add(new MyModelMetadataProvider());
m.ModelBindingMessageProvider.SetValueMustBeANumberAccessor(
fieldName => string.Format("'{0}' must be a valid number.", fieldName));
// you may check the document of `DefaultModelBindingMessageProvider`
// and add more if needed
})
;
}
参见DefaultModelBindingMessageProvider的文档
如果您可以阅读日语,请参阅这篇文章了解更多详细信息。
这在docs中有详细说明。您可以执行以下任一操作:
使用属性上的
ResourcePath
选项。
[Required(ResourcePath = "Resources")]
然后,您可以将本地化消息添加到
Resources/Namespace.To.MyClass.[lang].resx
。
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc()
.AddDataAnnotationsLocalization(options => {
options.DataAnnotationLocalizerProvider = (type, factory) =>
factory.Create(typeof(SharedResource));
});
}