Razor 表单没有传回控制器方法

Question

I am trying to pass a textbox's text back to a method in my controller, but the data is not being passed in the parameter I am genuinely confused, i'm following another example but i'm getting a different result, ie - my method behaving as if no parameter is passed

Code

public ActionResult Index(string searchString)        
    {
        ViewBag.Message = "Welcome to ASP.NET MVC!";

        var listOfAnimals = db.Animals.ToList();




        if (!String.IsNullOrEmpty(searchString))            
        {
            listOfAnimals = listOfAnimals.Where(a => a.AnimalName.ToLower().Contains(searchString.ToLower())).ToList();                                            

        }

        return View(listOfAnimals);
    }

and here is my razor form from my view page

@using(Html.BeginForm("Index", "Home"))
{ 
     @Html.TextBox("searchString")
     <input type="submit" id="Index" value="Index" />         
} 

Can anybody spot why this isn't working?

If more code is needed, please let me know but i think the issue is isolated to here

Answer 1

You code is correct.

Since you didn't add [HttpGet] or [HttpPost] before index method. This method was called twice.

The first call ran when producing the page with form via url http://server/Home/Index . This call was an http get and searchString mapped from URL was null, which is correct.

The second call ran when you clicked submit button. Correct value would be mapped by MVC correctly.

Answer 2

You need to have 2 Index actions (two methods), one without decorations (GET verb) and another one decorated with HttpPost (POST verb). Basically, when you go to the index page, the GET action is executed. When you submit the form, a POST request is executed and the Index decorated with HttpPost is executed.

// GET
public ActionResult Index() { ... }

// POST
[HttpPost]
public ActionResult Index(string searchString) { ... }

Answer 3

Francisco Goldenstein wrote the recommended way . It means you can have two Index() actions:

// for GET
public ActionResult Index() { ... }

// for POST
[HttpPost]
public ActionResult Index(string searchString) { ... }

However it is possible to have one Index() method for handling both (GET and POST) requests:

public ActionResult Index(string searchString = "") 
{
   if(!string.IsNullOrEmpty(searchString)
   { /* apply filter rule here */ }
}

You wrote, your code is not working. Do you mean, your action method is not requested after click on the button? Consider to allow empty value Index(string searchString = "")

If your action method is fired but variable is empty, check the name on the View() side. Textbox must not be disabled, of course.