ValidationLocalizationOptions.ErrorMessageKeyProvider Property

Definition

Namespace:

Microsoft.Extensions.Validation.Localization

Assembly:

Microsoft.Extensions.Validation.Localization.dll

Package:

Microsoft.Extensions.Validation.Localization v11.0.0-preview.5.26302.115

Source:

ValidationLocalizationOptions.cs

Gets or sets the delegate that determines the localization lookup key for a validation attribute's error message. When configured, the delegate is invoked for every attribute and takes precedence over ErrorMessage. Returning null or an empty string defers to using ErrorMessage directly as the lookup key.

public:
 property Func<Microsoft::Extensions::Validation::ErrorMessageLocalizationContext, System::String ^> ^ ErrorMessageKeyProvider { Func<Microsoft::Extensions::Validation::ErrorMessageLocalizationContext, System::String ^> ^ get(); void set(Func<Microsoft::Extensions::Validation::ErrorMessageLocalizationContext, System::String ^> ^ value); };

public Func<Microsoft.Extensions.Validation.ErrorMessageLocalizationContext,string?>? ErrorMessageKeyProvider { get; set; }

member this.ErrorMessageKeyProvider : Func<Microsoft.Extensions.Validation.ErrorMessageLocalizationContext, string> with get, set

Public Property ErrorMessageKeyProvider As Func(Of ErrorMessageLocalizationContext, String)

Property Value

Func<ErrorMessageLocalizationContext,String>

Remarks

When null (the default), only attributes with ErrorMessage set are localized (using the ErrorMessage value as the key); attributes without an explicit ErrorMessage are not localized at all.

When configured, the delegate can:

• Provide a fallback key for attributes without an explicit ErrorMessage (convention-based key selection).
• Transform an existing ErrorMessage into a different lookup key by reading Attribute's ErrorMessage from the context.
• Return null or an empty string to defer to the default behavior of using ErrorMessage as the key.

options.ErrorMessageKeyProvider = context =>
    $"{context.Attribute.GetType().Name}_ValidationError";
// This makes the localizer look up "RequiredAttribute_ValidationError"
// instead of "The {0} field is required."