I'm getting an error that Page is not working with HttpPost

Question

I'm not getting what's going on:

In my HomeController I have a:

public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }

    [HttpGet]
    public IActionResult Post()
    {
        return View(new Post());
    }

    [HttpPost]
    public IActionResult Edit(Post post)
    {
        return View();
    }
}

If I run my app and go to localhost8888/Home/Edit I get a 405 error with `

This Page is not working

However if I change EDIT method to [HttpGet] or remove the action all together the Edit razor view loads successfully.

Razor View:

@model Post


<div>
<form asp-controller="Home" asp-action="Edit" method="post">
    <div>
        <label>Title</label>
        <input asp-for="@Model.Title"/>

        <label>Body</label>
        <input asp-for="@Model.Body" />
    </div>
    <input type="submit" value="Submit"/>
</form>
</div>

Why is that happening?

Answer 1

When you navigate to /Home/Edit the browser makes a GET request to your server. So to handle this request you need an [HttpGet] method in your controller.

When you submit the form the browser sends a POST request to the server. So to handle this request you need an [HttpPost] method in your controller.

So basically you need two Edit methods one for handling the first scenario and one for the second.

public class HomeController : Controller
{
    ...
    ...

    // handles the GET when user navigates to /Home/Edit and returns the Edit View
    [HttpGet]
    public IActionResult Edit()
    {
        return View();
    }

    // handles the POST request when user submits the form and processes the user input
    [HttpPost]
    public IActionResult Edit(Post post)
    {
        if (!ModelState.IsValid)
        {
            // form input was not valid
            // return back to Edit view to show the validation errors
            return View(post);
        }
        
        // form input is valid
        // process the data, probably save to database

        // the post was edited successfully, redirect to Index View
        return RedirectToAction("Index");
    }
}