ASP.NET - ViewStart and ViewImports

ViewStart and ViewImports are special Razor files in ASP.NET MVC and Razor Pages that apply common configuration and behavior across multiple views. They help reduce repetition and keep view-related settings centralized and consistent.

Purpose of ViewStart
ViewStart is used to define logic that runs before every Razor view is rendered. Its most common purpose is to set a default layout so individual views do not need to specify the layout repeatedly. This ensures a consistent structure across the application.

How ViewStart Affects Views
When a view is rendered, ASP.NET Core looks for a ViewStart file starting from the current folder and moving upward. If multiple ViewStart files exist, they are executed in order. This allows different layouts or behaviors to be applied at different folder levels.

Purpose of ViewImports
ViewImports is used to define shared Razor directives for views. It centralizes namespace imports, tag helper registrations and other common directives so they do not need to be repeated in every view file.

What ViewImports Typically Contains
ViewImports usually includes namespace references for models, tag helper enabling and Razor directives. This keeps individual view files clean and focused only on markup and display logic rather than configuration.

Folder Scope and Inheritance
Both ViewStart and ViewImports follow folder-based scope rules. Files placed in the root Views folder apply to all views, while files in subfolders apply only to views within that folder. This supports organized and scalable view structures.

Why ViewStart and ViewImports Are Important
These files improve maintainability and consistency across MVC applications. By centralizing layouts and imports, developers can update behavior for many views at once, reducing duplication and minimizing errors.