ASP.NET Core Razor Pages and HTTP Status Control Flow

I, Khalid Abuhakmeh, recently wrote about my Razor Pages first impressions and am mostly positive about the addition to the ASP.NET Core technology stack. Bill Boga and I are currently rewriting a site that can benefit from the technology but thought it might be limited when dealing with control flow. Take this example of a PageModel.OnGet action.

public class IndexModel : PageModel
{
    Database db;
    public Post Post {get;set;}
    public IndexModel(Database db) {
        this.db = db;
    }
    public void OnGet(int id)
    {
        Post = db.Posts.Find(id);
    }
}

The OnGet action attempts to find a Post, but it may not find it based on the id. In a traditional ASP.NET MVC application we should return a NotFound result if the post is not present in our database.

What if I told you Razor Pages is no different? Let’s rework our OnGet method.

public class IndexModel : PageModel
{
    Database db;
    public Post Post {get;set;}
    public IndexModel(Database db) {
        this.db = db;
    }
    public IActionResult OnGet(int id)
    {
        Post = db.Posts.Find(id);
        // http status control flow
        if (Post == null)
            return NotFound();
        return View();
    }
}

In the example there are three parts to take note of:

1. IActionResult is now the return of OnGet and not void.
2. We can now return IActionResult types like NotFoundResult and ViewResult.
3. The action needs to return an IActionResult.

Razor Pages will respect the IActionResult return types and allow you to control flow with HTTP status codes, giving you the simplicity of Razor Pages and the power of ASP.NET MVC.