Question

我正在尝试在选择列表中使用内置的ASP.NET MVC 2客户端验证，如下所示：

 private SelectList _CategoryList;
        [Required(ErrorMessage = "Category Required")]
        [System.ComponentModel.DataAnnotations.Range(1, double.MaxValue, ErrorMessage = "Please Select A Category")]
        [DisplayName("Category")]
        public SelectList CategoryList
        {
            get
            {
                return new SelectList(Categories, "CatID", "CatFullName"); ;
            }
            set
            {
                _CategoryList = value;
            }
        }

但是它不起作用...如果选择默认值0，则不会显示验证消息，并且页面会像验证一样进行。想法？

Answer 1

好的，所以我在一个稍微不同的问题的答案中找到了答案。所以我在这里发布我的完整代码，扩展了Scott Guthries ASP.NET MVC 2验证帖子：http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx

我的ViewModel：

public class Person
{
    [Required(ErrorMessage="First Name Required")]
    [StringLength(50,ErrorMessage="Must be under 50 characters")]
    public string FirstName { get; set; }

    [Required(ErrorMessage="Last Name Required")]
    [StringLength(50, ErrorMessage = "Must be under 50 characters")]
    public string LastName { get; set; }

    [Required(ErrorMessage="Age Required")]
    [Range(1,120,ErrorMessage="Age Must be between 0 and 120")]
    public int Age { get; set; }

    [Required(ErrorMessage="Email Required")]
    public string Email { get; set; }


    public IEnumerable<SelectListItem> FavoriteColor { get; set; }


    [Range(0, 6, ErrorMessage = "Out of range")]
    public int SelectedFavColor { get; set; }
}

我的颜色类：

public class Colors
{
    public int ColorID { get; set; }
    public string ColorName { get; set; }
}

我的名单助手延期从Rob Connery手中偷走了，他从其他人那里偷走了它：

public static class ListExtensions
{
    public static IEnumerable<T> ForEach<T>(this IEnumerable<T> collection, Action<T> action)
    {
        foreach (var item in collection) action(item);
        return collection;
    }

    public static SelectList ToSelectList<T>(this IEnumerable<T> collection)
    {
        return new SelectList(collection, "Key", "Value");
    }

    public static SelectList ToSelectList<T>(this IEnumerable<T> collection, string selectedValue)
    {
        return new SelectList(collection, "Key", "Value", selectedValue);
    }

    public static SelectList ToSelectList<T>(this IEnumerable<T> collection,
                         string dataValueField, string dataTextField)
    {
        return new SelectList(collection, dataValueField, dataTextField);
    }

    public static SelectList ToSelectList<T>(this IEnumerable<T> collection,
                         string dataValueField, string dataTextField, string selectedValue)
    {
        return new SelectList(collection, dataValueField, dataTextField, selectedValue);
    }
}

我的控制器代码（是的，它可以重构为更干）：

public ActionResult Create()
    {
        Person newFriend = new Person();
        IList<Colors> colorslist = new List<Colors>();
        colorslist.Add(new Colors { ColorID = -1, ColorName = "Please Select Color" });
        colorslist.Add(new Colors { ColorID = 1, ColorName = "Red" });
        colorslist.Add(new Colors { ColorID = 2, ColorName = "Green" });
        colorslist.Add(new Colors { ColorID = 3, ColorName = "Blue" });

        newFriend.FavoriteColor = colorslist.ToSelectList("ColorID","ColorName","-1");
        return View(newFriend);
    }

    [HttpPost]
    public ActionResult Create(Person friendToCreate, FormCollection collection)
    {
        friendToCreate.SelectedFavColor = Convert.ToInt32(collection["SelectedFavColor"]);
        if (ModelState.IsValid)
        {
            return Redirect("/");
        }
        IList<Colors> colorslist = new List<Colors>();
        colorslist.Add(new Colors { ColorID = -1, ColorName = "Please Select Color" });
        colorslist.Add(new Colors { ColorID = 1, ColorName = "Red" });
        colorslist.Add(new Colors { ColorID = 2, ColorName = "Green" });
        colorslist.Add(new Colors { ColorID = 3, ColorName = "Blue" });
        friendToCreate.FavoriteColor = colorslist.ToSelectList("ColorID", "ColorName");
        return View(friendToCreate);
    }

我的页面标记：

<% using (Html.BeginForm()) {%>

    <fieldset>
        <legend>Fields</legend>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.FirstName) %>
        </div>
        <div class="editor-field">
            <%= Html.TextBoxFor(model => model.FirstName) %>
            <%= Html.ValidationMessageFor(model => model.FirstName) %>
        </div>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.LastName) %>
        </div>
        <div class="editor-field">
            <%= Html.TextBoxFor(model => model.LastName) %>
            <%= Html.ValidationMessageFor(model => model.LastName) %>
        </div>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.Age) %>
        </div>
        <div class="editor-field">
            <%= Html.TextBoxFor(model => model.Age) %>
            <%= Html.ValidationMessageFor(model => model.Age) %>
        </div>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.Email) %>
        </div>
        <div class="editor-field">
            <%= Html.TextBoxFor(model => model.Email) %>
            <%= Html.ValidationMessageFor(model => model.Email) %>
        </div>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.FavoriteColor) %>
        </div>
        <div class="editor-field">
            <%= Html.DropDownList("SelectedFavColor", Model.FavoriteColor, -1)%>
            <%= Html.ValidationMessageFor(model => model.SelectedFavColor) %>
        </div>

        <p>
            <input type="submit" value="Submit" />
        </p>
    </fieldset>

<% } %>

Answer 2

当我使用我的ViewModel时，我有一个属性CategoryId并将我的范围验证器放在那里，而不是下拉列表。 Selectlist只提供数据 - 您可以根据模型进行验证。

 [Required(ErrorMessage = "Category Required")]
    [System.ComponentModel.DataAnnotations.Range(1, double.MaxValue, ErrorMessage = "Please Select A Category")]
    [DisplayName("Category")]
    public int CategoryId {get;set;}

在视图中，我的下拉列表中包含我的类别的ID，但是我的类别中的列表：

<%= Html.DropDownList("CategoryId", (SelectList)Model.Categories, "(Select)")%>

当您的数据发回服务器时，您应该注意到该类包含id值。

Answer 3

我不认为它与DataAnnotations有关，因为当你将一个模型绑定到一个非可空的实体并且你试图将无效值放入时，它也会在没有它们的情况下发生。我所做的是从表单中发送ModelState [“XXXX”]。Value.AttemptedValue并对其进行验证，而不是实体中的属性。我想知道是否完全验证原始表单数据而不仅仅是问题项更合适。

类似的回复：ASP.NET MVC: DataAnnotations - Show an error message indicating that a field must be numeric

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