[c#] How to pass a textbox value from view to a controller in MVC 4?

Here i am fetching the value from database and showing it in a input field

<input type="text" id="ss" value="@item.Quantity"/>

and the value fetching from database is 1.Then i am changing the input field value to 2 and passing that value to the controller in a action click

 <a id="imgUpdate"  href="@Url.Action("Update", "Shopping", new { id = Request.QueryString["UserID"], productid = item.ProductID, qty = item.Quantity, unitrate = item.Rate })"> 

But in the controller part i am getting that old value1 for qty.But i need that updated value 2 in qty

public ActionResult Update(string id, string productid, int qty, decimal unitrate)
        {
            if (ModelState.IsValid)
            {
                int _records = UpdatePrice(id,productid,qty,unitrate);
                if (_records > 0)
                {
                    return RedirectToAction("Index1", "Shopping");
                }
                else
                {
                    ModelState.AddModelError("","Can Not Update");
                }
            }
            return View("Index1");
        }

Any suggestion?

EDIT:

     @using (Html.BeginForm("Update", "Shopping", FormMethod.Post))
     {

                @Html.Hidden("id", @Request.QueryString["UserID"] as string)
                @Html.Hidden("productid", item.ProductID as string)
                @Html.TextBox("qty", item.Quantity)
                @Html.Hidden("unitrate", item.Rate)

                <input type="submit" value="Update" />
     }

You can use simple form:

@using(Html.BeginForm("Update", "Shopping"))
{
    <input type="text" id="ss" name="qty" value="@item.Quantity"/>
    ...
    <input type="submit" value="Update" />
}

And add here attribute:

[HttpPost]
public ActionResult Update(string id, string productid, int qty, decimal unitrate)

When you want to pass new information to your application, you need to use POST form. In Razor you can use the following

View Code:

@* By default BeginForm use FormMethod.Post *@
@using(Html.BeginForm("Update")){
     @Html.Hidden("id", Model.Id)
     @Html.Hidden("productid", Model.ProductId)
     @Html.TextBox("qty", Model.Quantity)
     @Html.TextBox("unitrate", Model.UnitRate)
     <input type="submit" value="Update" />
}

Controller's actions

[HttpGet]
public ActionResult Update(){
     //[...] retrive your record object
     return View(objRecord);
}

[HttpPost]
public ActionResult Update(string id, string productid, int qty, decimal unitrate)
{
      if (ModelState.IsValid){
           int _records = UpdatePrice(id,productid,qty,unitrate);
           if (_records > 0){                    {
              return RedirectToAction("Index1", "Shopping");
           }else{                   
                ModelState.AddModelError("","Can Not Update");
           }
      }
      return View("Index1");
 }

Note that alternatively, if you want to use @Html.TextBoxFor(model => model.Quantity) you can either have an input with the name (respectecting case) "Quantity" or you can change your POST Update() to receive an object parameter, that would be the same type as your strictly typed view. Here's an example:

Model

public class Record {
    public string Id { get; set; }
    public string ProductId { get; set; }
    public string Quantity { get; set; }
    public decimal UnitRate { get; set; }
}

View

@using(Html.BeginForm("Update")){
     @Html.HiddenFor(model => model.Id)
     @Html.HiddenFor(model => model.ProductId)
     @Html.TextBoxFor(model=> model.Quantity)
     @Html.TextBoxFor(model => model.UnitRate)
     <input type="submit" value="Update" />
}

Post Action

[HttpPost]
public ActionResult Update(Record rec){ //Alternatively you can also use FormCollection object as well 
   if(TryValidateModel(rec)){
        //update code
   }
   return View("Index1");
}

Try the following in your view to check the output from each. The first one updates when the view is called a second time. My controller uses the key ShowCreateButton and has the optional parameter _createAction with a default value - you can change this to your key/parameter

@Html.TextBox("_createAction", null, new { Value = (string)ViewBag.ShowCreateButton })
@Html.TextBox("_createAction", ViewBag.ShowCreateButton )
@ViewBag.ShowCreateButton

I'll just try to answer the question but my examples very simple because I'm new at mvc. Hope this help somebody.

    [HttpPost]  ///This function is in my controller class
    public ActionResult Delete(string txtDelete)
    {
        int _id = Convert.ToInt32(txtDelete); // put your code           
    }

This code is in my controller's cshtml

  >   @using (Html.BeginForm("Delete", "LibraryManagement"))
 {
<button>Delete</button>
@Html.Label("Enter an ID number");
@Html.TextBox("txtDelete")  }  

Just make sure the textbox name and your controller's function input are the same name and type(string).This way, your function get the textbox input.

your link is generated when the page loads therefore it will always have the original value in it. You will need to set the link via javascript

You could also just wrap that in a form and have hidden fields for id, productid, and unitrate

Here's a sample for ya.

HTML

<input type="text" id="ss" value="1"/>
<br/>
<input type="submit" id="go" onClick="changeUrl()"/>
<br/>
<a id="imgUpdate"  href="/someurl?quantity=1">click me</a>

JS

function changeUrl(){
   var url = document.getElementById("imgUpdate").getAttribute('href');
   var inputValue = document.getElementById('ss').value;
   var currentQ = GiveMeTheQueryStringParameterValue("quantity",url);
    url = url.replace("quantity=" + currentQ, "quantity=" + inputValue);
document.getElementById("imgUpdate").setAttribute('href',url)
}

    function GiveMeTheQueryStringParameterValue(parameterName, input) {
    parameterName = parameterName.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
    var regex = new RegExp("[\\?&]" + parameterName + "=([^&#]*)");
    var results = regex.exec(input);
    if (results == null)
        return "";
    else
        return decodeURIComponent(results[1].replace(/\+/g, " "));
}

this could be cleaned up and expanded as you need it but the example works