如何在ASP.NET MVC中使用jQuery / Ajax将数据插入数据库？

Question

I have been stuck for hours trying to find the bugs when trying to insert data into database using ajax. When I click submit button, it just reloads but does not save. I am confused about this problem. I have searched many blogs but did not find accurate solution to this problem.

Model class

public class Semester
{       
    [Key]
    public int SemesterId { get; set; }

    [Display(Name = "Semester Code")]
    [Required(ErrorMessage = "please enter semester code")]
    public string SemesterCode { get; set; }

    [Display(Name = "Semester Name")]
    [Required(ErrorMessage = "Please enter semeter name")]
    public string SemesterName { get; set; }
}

Controller [HttpGet]

  public ActionResult SaveSemesterGet()
  {
    return View();
   }
   public JsonResult AsCreateSemester(Semester semester){


            db.Semesters.Add(semester);
            db.SaveChanges();


        return Json(semester, JsonRequestBehavior.AllowGet);
     }

Index view:

      @model CampusManagementApp.Models.Semester
      <h2>SaveSemesterGet</h2>
      <form method="POST">

      @Html.AntiForgeryToken()

      <div >
        <h4>Semester</h4>
        @Html.ValidationSummary(true)

        <div class="form-group">
        @Html.LabelFor(model => model.SemesterCode, new { @class = "control- 
     label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.SemesterCode)
            @Html.ValidationMessageFor(model => model.SemesterCode)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.SemesterName, new { @class = "control- 
   label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.SemesterName)
            @Html.ValidationMessageFor(model => model.SemesterName)
        </div>
    </div>

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" id="btn" value="SAVE"/>
        </div>
    </div>
 </div>

<div>
    @*   @Html.ActionLink("Back to List", "Index")*@
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}
<script src="~/Scripts/jquery-1.10.2.min.js"></script>
<script src="~/Scripts/jquery.validate.min.js"></script>
<script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>
<script>
    $(document).ready(function() {
           $("#btn").click(function(a) {

        a.preventDefault();
        var code = $("#SemesterCode").val();
        var name = $("#SemesterName").val();
        var jsonData = {
            SemesterCode: code,
            SemesterName: name
        };


        $.ajax({
            type: "POST",
            url: '@Url.Action("AsCreateSemester", "Semester")',
             data:  JSON.stringify(jsonData),
               dataType:"json",


            success:function(data) {
                alert(data.SemesterName+"successfully inserted");
            },

            failure: function () {
                alert("not successfull");
            }

        });
</script>

What can be done to get rid of this problem?

Answer 1

Why are you using a submit button? Since the JS function you made is handling the post, you don't need to use a submit button, which is causing the entire page to reload. Just use a normal button.

            <input type="button" id="btn" value="SAVE"/>

Answer 2

You have several issues in the view:

1) You're subscribed to click event of a submit button without preventing default action which submitting the form. This triggered POST action which redirect away into the controller action and reload the page without leaving any time for AJAX function to execute. You should use preventDefault() to cancel the default action of the button.

2) The controller which receives AJAX callback does not have [HttpPost] attribute while type: "POST" option is used. Consider adding [HttpPost] attribute on top of controller name.

3) Your AJAX property names list does not match with property names defined inside model class. Consider using a viewmodel which accepts two properties and use it as action parameter.

Therefore, the AJAX callback should have setup as in example below:

Viewmodel

public class SemesterVM
{
    public string SemesterCode { get; set; }
    public string SemesterName { get; set; }
}

View

<input type="button" id="btn" value="SAVE" />

JS (click event)

$('#btn').click(function (e) {
    e.preventDefault(); // prevent default submit

    var code = $("#SemesterCode").val();
    var name = $("#SemesterName").val();

    // all property names must be same as the viewmodel has
    var jsonData = {
        SemesterCode: code,
        SemesterName: name
    };

    $.ajax({
        type: "POST",
        url: '@Url.Action("SaveSemester", "Student")',
        contentType: "application/json;charset=utf-8",
        data: JSON.stringify(jsonData),
        dataType: "json",
        success: function() {
            // do something
        }
    });
});

Controller Action

[HttpPost]
public JsonResult SaveSemester(SemesterVM semester)
{
    // add semester data

    return Json(semester);
}

Answer 3

After changing the ajax() method like below it works.

       $.ajax({
            type: "POST",
            url: '@Url.Action("AsCreateSemester", "Semester")',

         data: {
             SemesterCode: code,
             SemesterName: name
         },



            success:function(data) {
                alert(data.SemesterName+"successfully inserted");
            },

            failure: function () {
                alert("not successfull");
            }

        });