In this lesson, you will learn how to extract your specialized UI components into a dedicated Razor Class Library (RCL) so they can be shared across multiple Blazor projects.
Moving Beyond Single Projects
Up until now, you have likely built components directly inside your main project’s Components folder. While this works for one app, it creates a maintenance nightmare when you want to use the same "DataGrid" or "ThemeSwitcher" component in a different application. Instead of copying and pasting code, you can package your components into a Razor Class Library (RCL).
An RCL is a specialized class library project that contains Razor components, CSS, and static assets. Once built, this library acts as a NuGet package or a simple project reference that any other Blazor application can consume.
Creating and Consuming a Library
To get started, create a new project of type Razor Class Library in your solution. Move your reusable components into this project. Ensure your namespace is set correctly (e.g., MyCompany.UI.Components).
In your main Blazor application, add a project reference to the library. You can then use your components in any Razor file just like you would a native component, provided you include the namespace at the top:
@using MyCompany.UI.Components
<MyCustomButton Text="Click Me" OnClick="HandleClick" />
Handling Static Assets
One of the most powerful features of an RCL is the ability to include CSS or images. When you place a CSS file inside the wwwroot folder of your library, the Blazor framework automatically exposes it. You can reference these styles in your main app using the path:
_content/{LIBRARY_NAME}/{FILE_NAME}.css
By isolating your components into an RCL, you create a "single source of truth." If you need to update the styling or behavior of a component, you change it once in the library, and every application referencing that library receives the update after a recompile. This promotes clean architectural boundaries and prevents code duplication across your enterprise suite.
Key Takeaway: Razor Class Libraries allow you to package UI components into independent, reusable modules that are consumed via project references or NuGet packages, effectively centralizing your design system.