RoleBasedDisplayTagHelper

RoleBasedDisplayTagHelper is a custom ASP.NET Core TagHelper for role and policy-based content rendering in Razor views. It helps you conditionally show or hide UI elements based on the authenticated user’s roles and authorization policies.

Features

• Conditional Display Based on Roles:
  Specify which roles can see certain content.
• Excluding Certain Roles:
  Hide specific content from particular roles.
• Authorization Policies:
  Leverage ASP.NET Core policies to refine access control.
• Require Multiple Roles:
  Optionally require that a user has all specified roles.
• Transparent Rendering:
  The wrapper tag is removed at runtime so only the inner content is rendered if conditions are met.

Installation

1. Via NuGet Package Manager Console:

   Install-Package RoleBasedDisplayTagHelper

2. Via .NET CLI:

   dotnet add package RoleBasedDisplayTagHelper

3. Add to Your _ViewImports.cshtml:

   @addTagHelper *, RoleBasedDisplayTagHelper

   Identifying the Assembly Name:
   The assembly name defaults to your project’s name unless specified in the .csproj. If the assembly is RoleBasedDisplayTagHelper, use that in the @addTagHelper directive.

Usage (Beginner-Friendly)

Basic Role Check:

<restricted-for include-roles="admin,manager">
    <p>This content is only visible to admins and managers.</p>
</restricted-for>

Excluding Roles:

<restricted-for exclude-roles="intern,guest">
    <p>This content is not visible to interns or guests.</p>
</restricted-for>

Using Policies:

<restricted-for policy="CanAccessAdminPanel">
    <p>Only users who meet the 'CanAccessAdminPanel' policy can see this.</p>
</restricted-for>

Requiring All Roles:

<restricted-for include-roles="admin,finance" require-all-roles="true">
    <p>You must be both 'admin' and 'finance' to see this content.</p>
</restricted-for>

Combining Roles and Policies:

<restricted-for policy="CanAccessReports" include-roles="manager" exclude-roles="intern">
    <p>Visible to managers who can access reports, but not to interns.</p>
</restricted-for>

Nesting (Further Restriction):

<restricted-for include-roles="staff">
    <h2>Staff Portal</h2>
    <restricted-for include-roles="manager">
        <h3>Management Only Section</h3>
    </restricted-for>
</restricted-for>

Beginner Tips

• Ensure Authentication is Setup:
  Make sure your application is using authentication and the current user principal has roles assigned. Without a valid user principal, the TagHelper will not show content.

• Check Spelling:
  Policy or role name typos can cause the content to disappear. Double-check everything matches the definitions in your authorization configuration.

• Use Browser Dev Tools:
  If you don’t see content, ensure it’s not a CSS issue. View the page source or use browser dev tools to confirm if the elements are actually missing or just visually hidden.

Advanced User Tips

• Define Your Own Authorization Policies:
  For more complex scenarios, implement custom authorization handlers and policies. For example:

  services.AddAuthorization(options =>
  {
      options.AddPolicy("CanAccessAdminPanel", policy => policy.RequireRole("admin"));
  });

Troubleshooting

• Content Doesn’t Appear:

  • Check user roles and policies.
  • Confirm the user is authenticated.
  • Ensure @addTagHelper * , RoleBasedDisplayTagHelper is correct.

• Tag Still Shows in the Rendered HTML:
  Make sure you have output.TagName = null; in the ProcessAsync method to remove the wrapper tag after checks succeed.

• Assembly Name Issues:
  By default, the assembly name is the project name. You can find it in your .csproj under <AssemblyName> or by checking the .dll name in bin/Release or bin/Debug.