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I working with mvc 5. I am loading data from Database Using ORM and fill a drop down list from the controller, like this.
ViewBag.Country_id = new SelectList(_db.Countries, "Country_id", "Description");
As i wanted an empty field first I am doing this in my HTML.
<div class="form-group">
@Html.LabelFor(model => model.Countries, "Country", htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.DropDownList("Country_id", null, htmlAttributes: new { @class = "form-control" }, optionLabel: "Choose a Country")
@Html.ValidationMessageFor(model => model.Country_id, "", new { @class = "text-danger" })
</div>
</div>
The empty choice has a "0" value.
And i wanted to validate the user choose a Country so I add this Validation
[Required,Range(1, int.MaxValue, ErrorMessage = "Error: Must Choose a Country")]
public int Country_id { get; set; }
The Problem is that never get me a Error. Always is "0" and the validation did not occur.
What I a missing?
567
You can validate the DropDownList value on form submission using jQuery Validator, by applying “ValidationRules” and “ValidationMessage” to the DropDownList. jquery. validate. min script file should be referred for validation, for more details, refer here.
Add the "[Required]" attribute to the field that you want to make mandatory for insertion. The required attribute requires the "System. ComponentModel. DataAnnotations" namespace.
SelectListItem is a class which represents the selected item in an instance of the System. Web. Mvc.
There are few ways to work with DropDownList. I personally like to use Strongly-Type ViewModel instead of ViewBag.
Validation message displays when submit button is clicked without selecting Country.
public class Country
{
public int Country_id { get; set; }
public string Description { get; set; }
}
public class CountryViewModel
{
[Display(Name = "Country")]
[Required(ErrorMessage = "{0} is required.")]
public int SelectedCountryId { get; set; }
public IList<SelectListItem> AvailableCountries { get; set; }
public CountryViewModel()
{
AvailableCountries = new List<SelectListItem>();
}
}
public class HomeController : Controller
{
public ActionResult Create()
{
var countries = GetCountries();
var model = new CountryViewModel {AvailableCountries = countries};
return View(model);
}
[HttpPost]
public async Task<ActionResult> Create(CountryViewModel countryViewModel)
{
if (ModelState.IsValid)
{
int countryId = countryViewModel.SelectedCountryId;
// Do something
}
// If we got this far, something failed. So, redisplay form
countryViewModel.AvailableCountries = GetCountries();
return View(countryViewModel);
}
public IList<SelectListItem> GetCountries()
{
// This comes from database.
var _dbCountries = new List<Country>
{
new Country {Country_id = 1, Description = "USA"},
new Country {Country_id = 2, Description = "UK"},
new Country {Country_id = 3, Description = "Canada"},
};
var countries = _dbCountries
.Select(x => new SelectListItem {Text = x.Description, Value = x.Country_id.ToString()})
.ToList();
countries.Insert(0, new SelectListItem {Text = "Choose a Country", Value = ""});
return countries;
}
}
@model DemoMvc.Models.CountryViewModel
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Create</title>
</head>
<body>
<h2>Create</h2>
@using (Html.BeginForm())
{
<div class="form-group">
@Html.LabelFor(model => model.SelectedCountryId,
new {@class = "control-label col-md-2"})
<div class="col-md-10">
@Html.DropDownListFor(model => model.SelectedCountryId,
Model.AvailableCountries, new {@class = "form-control"})
@Html.ValidationMessageFor(model => model.SelectedCountryId,
"", new {@class = "text-danger"})
</div>
</div>
<input type="submit" value="Submit"/>
}
</body>
</html>
For .net core instead of @Html.ValidationMessageFor(...
Use
razor cshtml
<span asp-validation-for="SelectedCountryId" class="text-danger"></span>
model poco
[Required(ErrorMessage = "Country is required.")]
public int SelectedCountryId { get; set; }
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