MVC Razor drop down list default value is not triggering onchange event

Question

I have a drop down list in c# MVC Razor application that is populated via enum data model object.My issue comes into play when the user selects the drop down the default value is the first value from the model and when it is selected the onchange event is not being triggered. Please see code below:

.net core mvc razor view

            <tr>
                <td>
                    <a id="GenderLnk" href="#">Click Here to Update</a><br>
                    <div id="GenderDiv" style="display:none;">
                        @using (Html.BeginForm("UpdateGender", "Home", FormMethod.Post))
                        {
                            @Html.DropDownListFor(m => m.StudentGender, new SelectList(Enum.GetValues(typeof(Gender))), new { @class = "show", onchange = "this.form.submit();" })
                        }
                    </div>
                </td>
            </tr>

Here is the model property

    public Gender StudentGender { get; set; }

    public enum Gender
    {
        Female,
        Male,
        [Display(Name ="Not Applicable")]
        NotApplicable,
        Transgender

    }

Answer 1

The reason for not triggering the "onChange" function is, it technically does not change any value in the form if user selected the default value in the first attempt. What you can do is provide a value like "please select" as the default value and let the user choose a value in the list.

@Html.DropDownListFor(m => m.StudentGender, new SelectList(Enum.GetValues(typeof(Gender))), "-- Please Select -- ", new { @class = "show", onchange = "this.form.submit();" })

May be you can use this question + answer into consideration as well. Hope this helps.

Get a default NULL value from DropDownList in ASP.NET MVC