Evaluating Claims in Views

Use tag helpers to conditionally render UI components based on user authorization.

Evaluating Claims in Views

In this lesson, you will learn how to use Tag Helpers to conditionally display UI elements in your Razor views based on specific user claims.

Why Evaluate Claims in Views?

While your controller actions or policy-based authorization handlers manage access to data, you often need to adjust the user interface based on a user's identity. For example, you might want to show an "Edit" button only to users who possess a Department claim with the value HR, or display a "Premium Content" badge to users with a SubscriptionLevel claim of Gold.

Rather than polluting your view with complex C# logic, you can use the asp-authorize and asp-policy Tag Helpers to keep your markup clean and declarative.

Using the Authorization Tag Helper

To use these helpers, ensure you have @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers in your _ViewImports.cshtml. Once enabled, you can wrap any HTML element—such as a div, button, or anchor—with authorization requirements.

If you have defined a policy named "ElevatedAccess" that checks for specific claims (e.g., EmployeeRole == Manager), you can apply it directly to your UI components:

<div asp-policy="ElevatedAccess">
    <button>Manage System Settings</button>
</div>

If the user does not satisfy the requirements of the "ElevatedAccess" policy, the entire div (and its contents) will be omitted from the rendered HTML. This prevents sensitive controls from even reaching the client's browser.

Direct Claim Access

For simple checks, you can still evaluate claims manually using the User object available in your Razor views:

@if (User.HasClaim(c => c.Type == "Department" && c.Value == "HR"))
{
    <a asp-action="ViewEmployeeRecords">Access HR Records</a>
}

While the asp-policy Tag Helper is preferred for consistency with your application's wider security architecture, using User.HasClaim provides a quick, lightweight way to handle dynamic UI requirements without defining a full policy for every minor variation.

Key Takeaway: Use the asp-policy Tag Helper to declaratively hide or show UI elements, ensuring that your view layer respects the security constraints defined by your authorization policies.