#### [Abblix\.Utils](https://www.abblix.com/en/docs/api/abblix-utils 'index')

## Abblix\.Utils\.Validation Namespace

| Classes | |
| :--- | :--- |
| [AbsoluteUriAttribute](https://www.abblix.com/en/docs/api/abblix-utils/Abblix.Utils.Validation.AbsoluteUriAttribute 'Abblix\.Utils\.Validation\.AbsoluteUriAttribute') | A validation attribute that requires the value to be an absolute URI and, optionally, to use a specific scheme\. Absence is valid \- combine with [System\.ComponentModel\.DataAnnotations\.RequiredAttribute](https://learn.microsoft.com/en-us/dotnet/api/system.componentmodel.dataannotations.requiredattribute 'System\.ComponentModel\.DataAnnotations\.RequiredAttribute') to also reject a missing value\. Shared by the MVC and Minimal API OIDC server adapters, whose source generators emit it \(with the marker's scheme argument\) from the declarative core `AbsoluteUri` marker\. \<param name="requireScheme"\>
 The URI scheme the value must use \(e\.g\. "https"\); any absolute scheme is accepted when null\.\</param\> |
| [AllowedValuesAttribute](https://www.abblix.com/en/docs/api/abblix-utils/Abblix.Utils.Validation.AllowedValuesAttribute 'Abblix\.Utils\.Validation\.AllowedValuesAttribute') | A validation attribute that restricts a string \(or string\-collection\) value to a fixed set, matched exactly\. An absent value passes: whether a member is required is a separate question, asked by a separate attribute, which is why the framework's own `AllowedValues` cannot stand in for this one \- it refuses null\. Shared by the MVC and Minimal API OIDC server adapters, whose source generators emit it onto a generated model whenever the corresponding core property carries the declarative `AllowedValues` marker\. |
| [ElementsRequiredAttribute](https://www.abblix.com/en/docs/api/abblix-utils/Abblix.Utils.Validation.ElementsRequiredAttribute 'Abblix\.Utils\.Validation\.ElementsRequiredAttribute') | A validation attribute that rejects a collection containing a null element; a non\-collection value is left untouched\. Shared by the MVC and Minimal API OIDC server adapters, whose source generators emit it from the declarative core `ElementsRequired` marker\. |