How To Validate DropDown List in Asp .net MVC

Question

The List of the month are Already added In Databases. For Adding the salary (Create operation), i have to select the month type from the Drop Down List, if the month is not selected the program should not have to redirect to create action. How Can i validate the Drop Down, Before Routing to Create Action ?

@using(Html.BeginForm("Create","Talab",FormMethod.Post))
{ 
    <div class="row">
        <div class="form-group">
            <div class="col-md-2">
                <a href="@Url.Action("Create","TotalSalary")" class="btn btn-success input-sm">Add New </a>
            </div>
        </div>
        <div class="form-group">   
            <div class="col-md-2">
                @Html.DropDownListFor(model => model.Month.id,     (IEnumerable<SelectListItem>)ViewData["monthType"], "--Select a Month--")
                @Html.ValidationMessageFor(model => model.Month.id)
            </div>
        </div>
    </div>
}

My View Model has following Property

public class Salary
{
   public int id { get; set; }
   public Nullable<int> month_id { get; set; }

   [Required]
   public virtual Month Month { get; set; }

   public IEnumerable<Month> GetMonths()
   {
        IEnumerable<Month> mat = null;
        mat = this.db.Months.ToList();
        return mat;
   }

}
Public Class Month
{
    public int id { get; set; }
    public string month { get; set; }
    public virtual ICollection<Salary> Salary { get; set; }
}

My Controller Action Index

public ActionResult Index()
    {
        Salary salary = new Salary();
        ViewData["monthType"] = salary .GetMonths().ToList().Select(
                 s => new SelectListItem
                 {
                     Text = s.month,
                     Value = s.id.ToString()
                 });

        return View(salary);
    }

As an aside, it is highly recommended you format your code cleanly so people can quickly and accurately understand what you're doing! — Nathaniel Ford
– Nathaniel Ford, Commented Aug 8, 2015 at 16:01
Just use the RequiredAttribute like any other input. The validation doesn't have anything to do with drop-down list or text box or whatever input you use. — ataravati
– ataravati, Commented Aug 8, 2015 at 16:06
Not It didnot work! I can Redirect to Create Action without Selecting any Value from the Drop Down. — Rasik
– Rasik, Commented Aug 8, 2015 at 16:19
If I understand you correctly, you want the Create link to be disabled if a month is not set in the drop-down list? Then you will have to validate with javascript. — Michael Fürstenberg
– Michael Fürstenberg, Commented Aug 8, 2015 at 19:32

Community · Accepted Answer · 2017-05-23 11:47:35Z

3

Your dropdownlist should bind to property month_id which is Nullable<int>, but you have not decorated it with the [Required] attribute. It needs to be

[Required(ErrorMessage="Please select a month")]
public Nullable<int> month_id { get; set; }

and in the view

@Html.DropDownListFor(m => m.month_id, ....)
@Html.ValidationMessageFor(m => m.month_id)

Side note: You claim your using a view model, but in fact your not. What you have shown is a data model. A view model contains only properties relevant to your view and should never contain method that access your database. Refer What is ViewModel in MVC?

A view model in your case would be

public class SalaryViewModel
{
  public int id { get; set; }
  [Required(ErrorMessage="Please select a month")]
  [Display(Name = "Month")] // for use in @Html.LabelFor()
  public Nullable<int> month_id { get; set; }
  public SelectList MonthList { get; set; } // or IEnumerable<SelectListItem> MonthList
}

Where you populate the MonthList property in the controller and use it in the view as

@Html.DropDownListFor(m => m.month_id, Model.MonthList, "--Select a Month--")

edited May 23, 2017 at 11:47

CommunityBot

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answered Aug 8, 2015 at 23:59

user3559349

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19 Comments

Rasik Over a year ago

What should be added to the Controller ?

user3559349 Over a year ago

Do your mean to populate the SelectList? If so, its just what you currently using to assign ViewData["monthType"]

Rasik Over a year ago

Your Solution Wont' Give My answer!! But Thank you

user3559349 Over a year ago

What do you mean wont give you the answer. Read the first paragraph. You binding to a property named month_id which is nullable but you don't have the required attribute so anything you select (including the "--Select a Month--" option) IS VALID. It is the CORRECT answer! The side note just points out how you should be doing it.

Rasik Over a year ago

@Html.DropDownListFor(model => model.Month.id, Model.MonthList, "--Select a Month--") ... Where is month_id... ?? drop down has nothing to do with month_id..if the month is selected, the id of that month is copied to month_id which is the property of Salary. otherwise, the Create link should be disabled

|

Community · Accepted Answer · 2017-05-23 10:29:51Z

2

Make sure you use required on the model.

[Required]
public int id { get; set; }

Validating required selection in DropDownList

https://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.requiredattribute(v=vs.110).aspx

edited May 23, 2017 at 10:29

CommunityBot

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answered Aug 8, 2015 at 16:11

Stephen King

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2 Comments

John H Over a year ago

Why are you making id nullable when it's required?

user3559349 Over a year ago

If it's int then the date-val-required attribute is added by default - a property that is typeof int is always required because it cant be null. The [Required] attribute is unnecessary unless you want to override the default error message using ErrorMessage="someMessage"

Community · Accepted Answer · 2017-05-23 12:18:33Z

1

Specify the range attribute

[Required]
[Range(1, 12, ErrorMessage="Please select a value")]
public int Id { get; set; }

Source : MVC3 validation with data-annotation?

edited May 23, 2017 at 12:18

CommunityBot

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answered Aug 8, 2015 at 16:30

gvk

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