Eine Null-Validierung aus der Dropdown-Liste schreiben MVC

Question

Ich arbeite an einer Anwendung asp.net MVC, die ein Textfeld und zwei Dropdown-Listen hat. Benutzer können einen numerischen Wert eingeben und aus der Liste von - bis auswählen. Mein Problem versucht, die Dropdown-Liste zu validieren, während ich versuchte, die erforderliche Validierung zu verwenden, aber nicht funktionierte. Ich habe auch versucht, die Dropdowns zu überprüfen, wenn Nullwerte gesendet werden, aber die Fehlerüberprüfung funktioniert nicht!

Der Fehlertyp:

There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'fromCurrency.Name'. 

Contorller

[HttpPost] 
     public ActionResult Index(Currencies cur) 
     { 
      if (ModelState.IsValid) 
      { 



       if (String.IsNullOrWhiteSpace(cur.fromCurrency.Name) || String.IsNullOrWhiteSpace(cur.toCurrency.Name)) 
       { 
        ModelState.AddModelError(string.Empty, "you can not leave the empty dropdown please select any of these"); 
       } 


       else 
       { 

        var fromCurrencyList = CurrenciesClient.GetFromCurrencyListAsync().Result; 

        ViewBag.FromCurrencies = new SelectList(fromCurrencyList, "CurrencyCode", "Name"); 

        var ToCurrencyList = CurrenciesClient.GetToCurrencyListAsync().Result; 

        ViewBag.ToCurrencies = new SelectList(ToCurrencyList, "CurrencyCode", "Name"); 


        var fromcurrname = cur.fromCurrency.Name; 
        string tocurrname = cur.toCurrency.Name; 

        //rate is taking by passing both dropdown currency code 
        decimal rate = CurrenciesClient.GetConversionRate("Currencies/GetConversionRate?fromcurrname=" + fromcurrname + "&tocurrname=" + tocurrname).Result; 
        ViewBag.TheResult = cur.CurrencyToConvert * rate; 


       } 

      } 
      return View(); 
     } 

Übersicht

@model ViewModel.Currencies 

@{ 
    ViewBag.Title = "Index"; 
} 

<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> 
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script> 

    <div id="ConversionSection"> 

     <form class="form-horizontal" method="post" id= "CurrencyConversion" action="/Currency/Index"> 
      @Html.ValidationSummary(true, "", new { @class = "text-danger" }) 
      <div class="form-group"> 
       <label class="col-sm-4 control-label"> 
        @Html.LabelFor(m => m.CurrencyToConvert, "Enter Currency") 
       </label> 
       <div class="col-sm-4"> 
        @Html.EditorFor(m => m.CurrencyToConvert, new { @class = " form-control" }) 
        @*@Html.ValidationMessageFor(m => m.CurrencyToConvert)*@ 
        @Html.ValidationMessageFor(m => m.CurrencyToConvert, "", new { @class = "text-danger" }) 


       </div> 
      </div> 
      <div class="form-group"> 
       <label class="col-sm-4 control-label"> 
        @Html.LabelFor(model => model.fromCurrency.Name, "From Currency") 
       </label> 
       <div class="col-sm-4"> 
        @Html.DropDownListFor(m => m.fromCurrency.Name, ViewBag.FromCurrencies as SelectList, "--select--", new { @class = " form-control" }) 
        @Html.ValidationMessageFor(model => model.fromCurrency.Name) 

       </div> 
      </div> 
      <div class="form-group"> 
       <label class="col-sm-4 control-label"> 
        @Html.LabelFor(model => model.toCurrency.Name, "To Currency") 
       </label> 
       <div class="col-sm-4"> 
        @Html.DropDownListFor(m => m.toCurrency.Name, ViewBag.ToCurrencies as SelectList, "--select--", new { @class = "form-control" }) 
        @*@Html.ValidationMessageFor(model => model.toCurrency.Name)*@ 

        @Html.ValidationSummary(false, "", new { @class = "text-danger" }) 


       </div> 
      </div> 

      <div class="form-group"> 
        <label class="col-sm-4 control-label"> 
         @Html.LabelFor(l => l.ConvertedCurrency, "Value") 
        </label> 
        <div class="col-sm-4"> 
         @Html.Editor("TheResult", new { @class = " form-control" }) 
        </div> 
      </div> 

      <div class="form-group"> 
       <div class="col-sm-offset-2 col-sm-4"> 
        <button type="submit" class="btn btn-success">Submit</button> 
       </div> 
      </div> 

     </form> 


    </div> 

Currencies.cs

public class Currencies 
    { 
     [Required] 
     [DataType(DataType.Currency)] 
     [DisplayFormat(ConvertEmptyStringToNull = false)] 
     public decimal CurrencyToConvert { get; set; } 


     public Currency fromCurrency { get; set; } 

     public Currency toCurrency { get; set; } 

     public double ConvertedCurrency { get; set; } 

    } 

Answer 1

Da nichts zurückgegeben wird, wenn Ihr Modellstatus ungültig ist. So viewbag.FromCurrencies und Viewbag.ToCurrencies sollte außerhalb von if (ModelState.IsValid) sein. Wenn Sie nicht Viewbag Eigenschaften Code nach if(ModelState.IsValid) Null Wert wird durch sie übergeben werden und Sie werden diese Ausnahme erhalten. Ich schreibe hier Refaktor Code in httppost Methode geschrieben.

[HttpPost] 
     public ActionResult Index(ConvertCurrencyViewModel cur) 
     { 
      if (ModelState.IsValid) 
      { 

        string fromcurrname = cur.fromCurrency.Name; 
        string tocurrname = cur.toCurrency.Name; 

        //rate is taking by passing both dropdown currency code 
        decimal rate = CurrencyClient.GetConversionRate("Currency/GetConversionRate?fromcurrname=" + fromcurrname + "&tocurrname=" + tocurrname).Result; 
        ViewBag.result = cur.CurrencyToConvert * rate; 

      } 
       //getting this select list value form Currency client class 
       var fromCurrencyList = CurrencyClient.GetFromCurrencyListAsync().Result; 

       ViewBag.FromCurrencies = new SelectList(fromCurrencyList, "CurrencyCode", "Name"); 

       var ToCurrencyList = CurrencyClient.GetToCurrencyListAsync().Result; 

       ViewBag.ToCurrencies = new SelectList(ToCurrencyList, "CurrencyCode", "Name"); 

       return View(); 

     } 

und modifizieren Sie Ihre curreny Klasse wie folgt Validierungsfehler zu zeigen.

public class Currencies 
    { 
     [Required(AllowEmptyStrings = false, ErrorMessage = "Please enter amount to convert")] 
     [DataType(DataType.Currency)] 
     [DisplayFormat(ConvertEmptyStringToNull = false)] 
     public decimal CurrencyToConvert { get; set; } 


     [Required(AllowEmptyStrings = false, ErrorMessage = "Please select country Name")] 
     public Currency fromCurrency { get; set; } 

     [Required(AllowEmptyStrings = false, ErrorMessage = "Please select country Name")] 
     public Currency toCurrency { get; set; } 

     public double ConvertedCurrency { get; set; } 
    } 

Dies wird Ihnen helfen, Ihre Felder zu validieren.