Binding complex model and DropDownListFor

Question

My entities:

public class Meal
{
    [HiddenInput(DisplayValue = false)]
    public int Id { get; set; }
    [Required(ErrorMessage = "Proszę podać nazwę posiłku")]
    public string Name { get; set; }
    [Required(ErrorMessage = "Proszę podać ilość białka")]
    [Range(0.00, double.MaxValue, ErrorMessage = "Proszę podać dodatnią ilość.")]
    public double Protein { get; set; }
    [Required(ErrorMessage = "Proszę podać ilość węglowodanów")]
    [Range(0.00, double.MaxValue, ErrorMessage = "Proszę podać dodatnią ilość.")]
    public double Carbohydrates { get; set; }
    [Required(ErrorMessage = "Proszę podać ilość tłuszczy")]
    [Range(0.00, double.MaxValue, ErrorMessage = "Proszę podać dodatnią ilość.")]
    public double Fat { get; set; }
    [Required(ErrorMessage = "Proszę podać ilość kalorii")]
    [Range(0.00, double.MaxValue, ErrorMessage = "Proszę podać dodatnią ilość.")]
    public double Calories { get; set; }
}

public class EatenMeal
{
    public int Id { get; set; }
    public virtual Meal Meal { get; set; }
    public virtual MealType MealType { get; set; }
    public double Serving { get; set; }
    public string Username { get; set; }
    public DateTime Date { get; set; }
}

public class MealType
{
    public int Id { get; set; }
    public string Name { get; set; }
}

In MealController's view MealList which displays meals from datebase. And there is a button "Add" which refers to action AddEatenMeal in EatenMealController.

public ActionResult AddEatenMeal(int id)
{
    var meal = mealRepository.GetMeal(id);
    EatenMeal eatenMeal = new EatenMeal() { Meal = meal, Username = User.Identity.Name };
    return View(eatenMeal);
}

[HttpPost]
public ActionResult AddEatenMeal(EatenMeal eatenMeal)
{
    if(ModelState.IsValid)
    {
        eatenMealRepository.AddEatenMeal(eatenMeal);
        RedirectToAction("Index", "Home");
    }
    return RedirectToAction("Index", "Home");
}

I am creating there object EatenMeal and partially initializing this object. Then I am passing this object to View to further initializing.

@model Domain.Entities.EatenMeal

@{
    ViewBag.Title = "Dodawanie posiłku do dziennika";
}

@using (Html.BeginForm("AddEatenMeal","EatenMeal", FormMethod.Post, new {@class = "form"}))
{
    @Html.HiddenFor(x => x.Meal.Name)
    @Html.HiddenFor(x => x.Username)
    @Html.HiddenFor(x => x.Meal.Calories)
    @Html.HiddenFor(x => x.Meal.Carbohydrates)
    @Html.HiddenFor(x => x.Meal.Fat)
    @Html.HiddenFor(x => x..Meal.Protein)
    @Html.HiddenFor(x => x.Meal.Id)
    @Html.HiddenFor(x=>x.Username)
    <div class="form-group">
        @Html.Label("Nazwa posiłku")
        @Html.Label(Model.Meal.Name, new { @class = "form-control" })
    </div>
    <div class="form-group">
        @Html.Label("Porcja (g)")
        @Html.TextBoxFor(x => x.Serving, new { @class = "form-control" })
    </div>
    <div class="form-group">
        @Html.Label("Typ posiłku")
        @Html.DropDownListFor(x=>x.MealType)????
    </div>
    <div class="form-group">
        @Html.Label("Data spożycia")
        @Html.TextBoxFor(x => x.Date, new { @class = "form-control", @id="date-eaten", @Value=DateTime.Today.ToShortDateString()})
    </div>
    <input type="submit" class="btn btn-info" value="Dodaj" />
}

Now I have a question. Is it correct to hiding fields? I don't know how I can save data from first controller to second in other way. And is a second question. How I can make DropDownListFor for property MealTye in EatenMeal?

Answer 1

Rather than sending and receiving a whole lot of unused data across the wire and opening yourself to over posting attack, create a view model that represents what you want to display and edit. See What is a view model in MVC?

View model

public class EatenMealVM
{
  public int MealID { get; set; }
  [Display(Name="Nazwa posiłku")]
  public string MealName { get; set; }
  [Display(Name = "Typ posiłku")]
  [Required(ErrorMessage = "Please select a meal")]
  public int? MealTypeID { get; set; }
  [Display(Name = "Porcja (g)")]
  public double Serving { get; set; } // is this really double?
  [Display(Name = "Data spożycia")]
  [DataType(DataType.Date)]
  public DateTime Date { get; set; }
  public SelectList MealTypeList { get; set; }
}

Controller

public ActionResult AddEatenMeal(int id)
{
  var meal = mealRepository.GetMeal(id);
  var mealTypes = // get the list of meal types from the database
  EatenMealVM model = new EatenMealVM()
  {
    MealID = meal.Id,
    MealName = meal.Name,
    MealTypeList = new SelectList(mealTypes, "ID", "Name")
  };
  return View(model);
}

View

@model EatenMealVM
....
@using (Html.BeginForm())
{
  @Html.HiddenFor(m => m.MealID)

  @Html.DisplayNameFor(m => m.MealName)
  @Html.DisplayFor(m => m.MealName)

  @Html.LabelFor(m => m.MealTypeID)
  @Html.DropDownListFor(m => m.MealTypeID, Model.MealTypeList, "--Please select--")
  @Html.ValidationMessageFor(m => m.MealTypeID)

  @Html.LabelFor(m => m.Serving)
  @Html.TextBoxFor(m => m.Serving, new { @class = "form-control")
  @Html.ValidationMessageFor(m => m.Serving)

  @Html.LabelFor(m => m.Date)
  @Html.TextBoxFor(m => m.Date)
  @Html.ValidationMessageFor(m => m.Date, new { @class = "form-control" })

  <input type="submit" class="btn btn-info" value="Dodaj" />
}

Post method

[HttpPost]
public ActionResult AddEatenMeal(EatenMealVM model)
{
  if (!ModelState.IsValid)
  {
    var mealTypes = // get the list of meal types from the database
    model.MealTypeList = new SelectList(mealTypes, "ID", "Name");
    return View(model);
  }
  // Initialize new EatenMeal class
  // Map properties from view model (including setting user name) 
  // Save and redirect
}

Note also the use of [Display] attribute and @Html.LabelFor(). Currently you not creating 'real' labels (they are not associated with the corresponding control)