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Null Value is passing to Controller

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User-797751191 posted

I have below code and Parameter is of string datatype

public JsonResult DeleteUser(string UsrName)
        {
            return Json(usrDB.DeleteUser(UsrName), JsonRequestBehavior.AllowGet);
        }

function Delete(UsrName) {
    var ans = confirm("Are you sure you want to delete this Record?");
    if (ans) {
        $.ajax({
            url: '/Home/DeleteUser/',
            data: JSON.stringify({ UserName : UsrName }),
            type: "POST",
            contentType: "application/json;charset=UTF-8",
            dataType: "json",
            success: function (result) {
                loadData();
            },
            error: function (errormessage) {
                alert(errormessage.responseText);
            }
        });
    }
}

Thanks

Wednesday, October 23, 2019 7:04 AM

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User665608656 posted

Hi jsshivalik,

According to your code, I found that the parameter you passed from Ajax is just a string type UsrName, not an entity .

I made a case of deleting data in MVC. You can refer to the following code:

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <script src="~/Scripts/jquery-3.3.1.min.js"></script>
    <script type="text/javascript">
 
        function Delete(UsrName) {
            event.preventDefault();
            var ans = confirm("Are you sure you want to delete this Record?");
            if (ans) {
                $.ajax({
                    url: '/C_1023_2160919/DeleteUser',
                    data: "{ UsrName:'" + $(UsrName).attr('id') + "'}",
                    type: "POST",
                    contentType: "application/json;charset=UTF-8",
                    dataType: "json",
                    success: function (result) {
                        alert(result);
                        location.href = "/C_1023_2160919/Index";
                    },
                    error: function (errormessage) {
                        alert(errormessage.responseText);
                    }
                });
            }
        }


    </script>
</head>
<body>
    <table id="tblCustomers" class="table" cellpadding="0" cellspacing="0" style="border-collapse:collapse;text-align:center" border="1">
        <tr>
            <th style="width:100px">EmplId</th>
            <th style="width:150px">FirstName</th>
            <th style="width:100px">LastName</th>
            <th style="width:150px">EmailAddr</th>
        </tr>
        @foreach (var customer in Model)
        {
            <tr>
                <td class="EmplId">
                    <span>@customer.EmplId</span>
                </td>
                <td class="FirstName">

                    <span>@customer.FirstName</span>
                </td>
                <td class="FirstName">

                    <span>@customer.LastName</span>
                </td>
                <td class="FirstName">

                    <span>@customer.EmailAddr</span>
                </td>
                <td>
                    @Html.ActionLink("Delete", "Delete", null, new { id = customer.EmplId, @class = "delete", onclick = "Delete(this);" })
                </td>
            </tr>
        }
    </table>

</body>
</html>

 public class C_1023_2160919Controller : Controller
    {
        // GET: C_1023_2160919
        public ActionResult Index()
        {
            Entities2 entity = new Entities2();
            List<Employee> customers = entity.Employees.ToList();
            return View(customers);
        }
        [HttpPost]
        public JsonResult DeleteUser(string UsrName)
        {
            return Json(DeleteUserMethod(UsrName), JsonRequestBehavior.AllowGet);
        }
        public string DeleteUserMethod(string UsrName)
        {
            string deleteMessage = string.Empty;
            int id = Convert.ToInt32(UsrName);
            try
            {
                using (EntityData entities = new EntityData())
                {
                    Employee customer = (from c in entities.Employees
                                         where c.EmplId == id
                                         select c).FirstOrDefault();
                    entities.Employees.Remove(customer);
                    entities.SaveChanges();
                }
                deleteMessage = "delete successfully!";
            }
            catch (Exception ex)
            {
                deleteMessage = ex.Message.ToString();
            }

            return deleteMessage;


        }
    }

Here is the result of this work demo:

Best Regards,

YongQing.

Wednesday, October 23, 2019 9:23 AM

User-797751191 posted

Hi Yong

I have below html

function loadData() {
    $.ajax({
        url: "/Home/List",
        type: "GET",
        contentType: "application/json;charset=utf-8",
        dataType: "json",
        success: function (result) {
            var html = '';
            $.each(result, function (key, item) {
                html += '<tr>';
                html += '<td>' + item.UserName + '</td>';
                html += '<td>' + item.Password + '</td>';
                html += '<td>' + item.FirstName + '</td>';
                html += '<td>' + item.LastName + '</td>';
                html += '<td><a href="#" onclick="return getbyName(\'' + item.UserName + '\')">Edit</a> | <a href="javascript:void(0)" onclick="Delete(\'' + item.UserName + '\')">Delete</a></td>';
                html += '</tr>';
            });
            $('.tbody').html(html);
        },
        error: function (errormessage) {
            alert(errormessage.responseText);
        }
    });
}

Thanks

Wednesday, October 23, 2019 1:49 PM

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User1120430333 posted

/Home/GetbyName?UsrName=" + '$('#UserName').val(result.UserName).ToString();

You can't do something like above? It's been sometime since I have used Jquery
And Username is spelled wrong in the action method too.

Wednesday, October 23, 2019 6:01 PM

User665608656 posted

Hi jsshivalik,

According to your code, you didn't explain the issue you were having, but I combined the data loading code and the deletion method you provided to create a case that you can refer to:

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
    <script src="~/Scripts/jquery-3.3.1.min.js"></script>
    <script type="text/javascript">
        function loadData() {
            $.ajax({
                url: "/C_1023_2160919/List",
                type: "GET",
                contentType: "application/json;charset=utf-8",
                dataType: "json",
                success: function (result) {
                    var html = '';
                    $.each(result, function (key, item) {
                        html += '<tr>';
                        html += '<td>' + item.EmplId + '</td>';
                        html += '<td>' + item.FirstName + '</td>';
                        html += '<td>' + item.LastName + '</td>';
                        html += '<td>' + item.EmailAddr + '</td>';
                        html += '<td><a href="#" onclick="return getbyName(\'' + item.EmplId + '\')">Edit</a> | <a href="javascript:void(0)" onclick="Delete(\'' + item.EmplId + '\')">Delete</a></td>';
                        html += '</tr>';
                    });
                    $('.tbody').html(html);
                },
                error: function (errormessage) {
                    alert(errormessage.responseText);
                }
            });
        }
        function Delete(UsrName) {
            event.preventDefault();
            var ans = confirm("Are you sure you want to delete this Record?");
            if (ans) {
                $.ajax({
                    url: '/C_1023_2160919/DeleteUser',
                    data: "{ UsrName:'" + UsrName + "'}",
                    type: "POST",
                    contentType: "application/json;charset=UTF-8",
                    dataType: "json",
                    success: function (result) {
                        alert(result);
                        loadData();
                    },
                    error: function (errormessage) {
                        alert(errormessage.responseText);
                    }
                });
            }
        }


    </script>
</head>
<body onload="loadData()">
    <table id="tblCustomers" class="table" cellpadding="0" cellspacing="0" style="border-collapse:collapse;text-align:center" border="1">
        <thead>
            <tr>
                <th style="width:100px">EmplId</th>
                <th style="width:150px">FirstName</th>
                <th style="width:100px">LastName</th>
                <th style="width:150px">EmailAddr</th>
                <th> </th>
            </tr>
        </thead>
        <tbody class="tbody"></tbody>
    </table>

</body>
</html>

public class C_1023_2160919Controller : Controller
    {
        // GET: C_1023_2160919
        public ActionResult Index()
        {
            return View();
        }
        [HttpGet]
        public JsonResult List()
        {
            Entities2 entity = new Entities2();
            List<Employee> customers = entity.Employees.ToList();
            return Json(customers, JsonRequestBehavior.AllowGet);
        }
        [HttpPost]
        public JsonResult DeleteUser(string UsrName)
        {
            return Json(DeleteUserMethod(UsrName), JsonRequestBehavior.AllowGet);
        }
        public string DeleteUserMethod(string UsrName)
        {
            string deleteMessage = string.Empty;
            int id = Convert.ToInt32(UsrName);
            try
            {
                using (EntityData entities = new EntityData())
                {
                    Employee customer = (from c in entities.Employees
                                         where c.EmplId == id
                                         select c).FirstOrDefault();
                    entities.Employees.Remove(customer);
                    entities.SaveChanges();
                }
                deleteMessage = "delete successfully!";
            }
            catch (Exception ex)
            {
                deleteMessage = ex.Message.ToString();
            }

            return deleteMessage;


        }
    }

Here is the result of this work demo:

Best Regards,

YongQing.

Thursday, October 24, 2019 5:44 AM

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Null Value is passing to Controller

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