参数字典包含一个 null 条目，用于不可为空类型“System.Int32”的参数“id”

Question

I am building My first MVC application, I have a table in database containing 3 columns:

1. Id → primary key
2. Username
3. password

When I am clicking on edit link edit a record, its throwing following exception:

The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Edit(Int32)' in 'MvcApplication1.Controllers.UserController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters

Here is my edit code:

public ActionResult Edit(int id, User collection)
{
    UserDBMLDataContext db = new UserDBMLDataContext();
    var q = from abc in db.User_Login_Details
            where abc.Id == id
            select abc;

    IList lst = q.ToList();

    User_Login_Details userLook = (User_Login_Details)lst[0];

    userLook.Username = collection.UserName;
    userLook.Password = collection.Password;
    db.SubmitChanges();
    return RedirectToAction("Index");                  
}

Answer 1

You are expecting an id parameter in your URL but you aren't supplying one. Such as:

http://yoursite.com/controller/edit/12
                                    ^^ missing

Answer 2

in your WebApiConfig >> Register () You have to change to

config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }

Here the routeTemplate , is added with {action}

Answer 3

This error means that the MVC framework can't find a value for your id property that you pass as an argument to the Edit method.

MVC searches for these values in places like your route data, query string and form values.

For example the following will pass the id property in your query string:

/Edit?id=1

A nicer way would be to edit your routing configuration so you can pass this value as a part of the URL itself:

/Edit/1

This process where MVC searches for values for your parameters is called Model Binding and it's one of the best features of MVC. You can find more information on Model Binding here .

Answer 4

Is the action method on your form pointing to /controller/edit/1 ?

Try using one of these:

// the null in the last position is the html attributes, which you usually won't use
// on a form.  These invocations are kinda ugly
Html.BeginForm("Edit", "User", new { Id = Model.Id }, FormMethod.Post, null)

Html.BeginForm(new { action="Edit", controller="User", id = Model.Id })

Or inside your form add a hidden "Id" field

@Html.HiddenFor(m => m.Id)

Answer 5

You get that error because ASP.NET MVC cannot find an id parameter value to provide for the id parameter of your action method.

You need to either pass that as part of the url, ("/Home/Edit/123"), as a query string parameter ("/Home/Edit?id=123") or as a POSTed parameter (make sure to have something like <input type="hidden" name="id" value="123" /> in your HTML form).

Alternatively, you could make the id parameter be a nullable int ( Edit(int? id, User collection) {...} ), but if the id were null, you wouldn't know what to edit.

Answer 6

I also had same issue. I investigated and found missing {action} attribute from route template.

Before code (Having Issue):

config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

After Fix(Working code):

config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

Answer 7

This might be useful for someone who has everything done right still facing issue. For them "above error may also cause due to ambiguous reference".

If your Controller contains

using System.Web.Mvc;

and also

using System.Web.Http;

It will create ambiguity and by default it will use MVC RouteConfig settings instead of WebApiConfig settings for routing . Make sure for WebAPI call you need System.Web.Http reference only

Answer 8

I was facing the Same Error.

Solution: The name of the variable in the View through which we are passing value to Controller should Match the Name of Variable on Controller Side.

.csHtml (View) :

@Html.ActionLink("Edit", "Edit" , new { id=item.EmployeeId })

.cs (Controller Method):

 [HttpGet]
            public ActionResult Edit(int id)
            {
                EmployeeContext employeeContext = new EmployeeContext();
                Employee employee = employeeContext.Employees.Where(emp => emp.EmployeeId == id).First();
                return View(employee);
            }

Answer 9

Make the id parameter be a nullable int:

public ActionResult Edit(int? id, User collection)

And then add the validation:

if (Id == null) ...

Answer 10

Just in case this helps anyone else; this error can occur in Visual Studio if you have a View as the open tab, and that tab depends on a parameter.

Close the current view and start your application and the app will start 'Normally'; if you have a view open, Visual Studio interprets this as you want to run the current view.

Answer 11

Just change your line of code to

<a href="~/Required/Edit?id=@item.id">Edit</a>

from where you are calling this function that will pass corect id

Answer 12

I had the same error, but for me, the issue was that I was doing the request with a wrong GUID. I missed the last 2 characters.

360476f3-a4c8-4e1c-96d7-3c451c6c86
360476f3-a4c8-4e1c-96d7-3c451c6c865e

Answer 13

如果 appconfig 或 webconfig 中不存在，只需添加属性路由

config.MapHttpAttributeRoutes()

Answer 14

If you're confused why your id is passing a null value via your razor file, I had the order of the overload wrong. You don't have to worry about it being nullable in this case.

Example:

This will NOT pass your id , since the overload is not in the correct position:

@Html.ActionLink("Edit", "Edit", "Controller", new { @class = "btn btn-primary" }, new { @id = x.Id })

This is the correct order to pass id , with html attributes after:

@Html.ActionLink("Edit", "Edit", "Controller", new { @id = x.Id }, new { @class = "btn btn-primary" })

Answer 15

@Html.ActionLink(item.Name, "Edit", new { id = item.Id }) here notice that parameters given to the ActionLink() is in order.

1. first parameter is for the text field to show on-page.
2. second one is for action URL.
3. List one is for ID reference.

Answer 16

I had the same error, but for me, the issue was that

I need to add in Index view the following missing in details action link

new { id = item.user_id}

This is the complete code:

    @foreach (var item in Model)
 {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.user_id)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.user_name)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.user_password)
            </td>
    
            @Html.ActionLink("Details", "Details", new { id = item.user_id}) 
               
        </tr>
    }