blocks|key|4658413|text|尝试将LicenseTypes+start的Index从1改为0，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4658414|public+enum+LicenseTypes
{
++++Trial+=+1,
++++Paid+=+2
}|code-block|syntax|javascript|4658415|然后，您可以使用Range+attribute验证所选的许可证类型，如下所示：|4658416|public+class+YourViewModel
{
+++++//Other+properties
+++++[Range(1,int.MaxValue,ErrorMessage+=+"Select+a+correct+license")]
+++++public+LicenseTypes+LicenseTypes+{+get;+set;+}
}|4658417|最后，在您的观点中：|4658418|+++@Html.EnumDropDownListFor(m+=>+m.LicenseTypes,"Select+a+license",new+{+@class+=+"form-control"})
+++@Html.ValidationMessageFor(m+=>+m.LicenseTypes)|4658419|entityMap^0|3|C|M|5|S|1|V|1|0|0|8|F|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|18|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|T|$]]

<p>Try to change the <code>Index</code> of <code>LicenseTypes</code> start from <code>1</code> not <code>0</code> like below:</p>

<pre><code>public enum LicenseTypes
{
    Trial = 1,
    Paid = 2
}
</code></pre>

<p>Then you can use <code>Range attribute</code> to validate the selected license type like below:</p>

<pre><code>public class YourViewModel
{
     //Other properties
     [Range(1,int.MaxValue,ErrorMessage = "Select a correct license")]
     public LicenseTypes LicenseTypes { get; set; }
}
</code></pre>

<p>Finally, in your view:</p>

<pre><code>   @Html.EnumDropDownListFor(m =&gt; m.LicenseTypes,"Select a license",new { @class = "form-control"})
   @Html.ValidationMessageFor(m =&gt; m.LicenseTypes)
</code></pre>


blocks|key|4658587|text|在呈现EnumDropDownListFor时，SelectedLicense已经具有该类型的默认值，即0。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4658588|只需将SelectedLicense属性的类型更改为可以为空的枚举，如下所示：|4658589|public+LicenseTypes?+SelectedLicense+{+get;+set;+}|code-block|syntax|javascript|4658590|这还允许您继续使用Required属性，我认为该属性更加简洁。Required属性不允许null响应，因此即使您的模型允许null，表单也不允许。|4658591|entityMap^0|3|J|O|F|1G|1|0|3|F|0|0|9|8|V|8|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|P|$]]

<p>By the time your <code>EnumDropDownListFor</code> is rendered <code>SelectedLicense</code> already has the default value for the type, which is <code>0</code>. </p>

<p>Just change the type of your <code>SelectedLicense</code> property to a nullable enum, like so:</p>

<pre><code>public LicenseTypes? SelectedLicense { get; set; }
</code></pre>

<p>This also allows you to continue using the <code>Required</code> attribute, which I think is significantly cleaner. The <code>Required</code> attribute will not allow a null response, so even though your model allows nulls, the form will not.</p>


blocks|key|152263|text|我有一个枚举：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|152264|public+enum+Sex
{
++++Male,
++++Female
}|code-block|syntax|javascript|152265|在我的模型中，我有：|152266|++++[DisplayName("Sex")]
++++[Required]
++++public+Sex?+Sex+{+get;+set;+}|152267|视图中的一个：|152268|++++@Html.EnumDropDownListFor(model+=>+model.Sex,+"Select+sex",+new+{+@class+=+"form-control",+type+=+"text"})|152269|通过这个，我有一个带有默认选项"Select+Female“的下拉列表，但验证只接受enum提供的选项("Male”和"Female")。|152270|在MVC3+(没有EnumDropDownListFor)中，我在模型中使用：|152271|++++[DisplayName("Sex")]
++++[Required(AllowEmptyStrings=false)]
++++public+Sex?+Sex+{+get;+set;+}

++++Sex+=+null;

++++Sexes+=+Repository.GetAutoSelectList<Sex>("");|152272|视图中：|152273|++++@Html.DropDownListFor(model+=>+model.Sex,+Model.Sexes,+new+{+@class+=+"form-control",+type+=+"text"+})|152274|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|17|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|18|8|@]|9|@]|A|$E|F]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|D|7|1A|8|@]|9|@]|A|$E|F]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

<p>I have an enum:</p>

<pre><code>public enum Sex
{
    Male,
    Female
}
</code></pre>

<p>In my model I have:</p>

<pre><code>    [DisplayName("Sex")]
    [Required]
    public Sex? Sex { get; set; }
</code></pre>

<p>An in the view:</p>

<pre><code>    @Html.EnumDropDownListFor(model =&gt; model.Sex, "Select sex", new { @class = "form-control", type = "text"})
</code></pre>

<p>By this I have a dropdown with default option "Select sex", but validation accepts only options provided by enum ("Male" and "Female").</p>

<p>In MVC3 (without EnumDropDownListFor) I used in model:</p>

<pre><code>    [DisplayName("Sex")]
    [Required(AllowEmptyStrings=false)]
    public Sex? Sex { get; set; }

    Sex = null;

    Sexes = Repository.GetAutoSelectList&lt;Sex&gt;("");
</code></pre>

<p>In view:</p>

<pre><code>    @Html.DropDownListFor(model =&gt; model.Sex, Model.Sexes, new { @class = "form-control", type = "text" })
</code></pre>


blocks|key|152300|text|ViewModel类需要在枚举属性上设置缺省值，才能成为缺省的选定公共类|type|unstyled|depth|inlineStyleRanges|entityRanges|data|152301|public+class+Test
++++{
++++++++public+Cars+MyCars+{+get;+set;+}
++++++++public+enum+Cars
++++++++{
++++++++++++[Display(Name+=+@"Car+#1")]
++++++++++++Car1+=+1,
++++++++++++[Display(Name+=+@"Car+#2")]
++++++++++++Car2+=+2,
++++++++++++[Display(Name+=+@"Car+#3")]
++++++++++++Car3+=+3
++++++++}

++++}|code-block|syntax|javascript|152302|控制器：|152303|+public+class+EnumController+:+Controller
++++{
++++++++//+GET:+Enum
++++++++public+ActionResult+Index()
++++++++{
++++++++++++var+model+=+new+Test+{MyCars+=+Test.Cars.Car3};+//+set+default+value
++++++++++++return+View(model);
++++++++}
++++++++[HttpPost]
++++++++public+ActionResult+Index(Test+model)
++++++++{
++++++++++++.....
++++++++}
++++}|152304|查看：|152305|@Html.BeginForm()
{
<div+class="panel+bg-white">
++++<div+class="panel-header+fg-white">
++++++++Enums
++++</div>
++++<div+class="panel-content">
++++++++<div+class="input-control+select+size3">
++++++++++++@Html.EnumDropDownListFor(model+=>+model.MyCars)

++++++++</div>
++++</div>
++++<input+type="submit"+class="button+success+large"+/>
</div>
}|152306|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

<p>The ViewModel class needs to have the default value set on the enum property for it to be the default selected
public </p>

<pre><code>public class Test
    {
        public Cars MyCars { get; set; }
        public enum Cars
        {
            [Display(Name = @"Car #1")]
            Car1 = 1,
            [Display(Name = @"Car #2")]
            Car2 = 2,
            [Display(Name = @"Car #3")]
            Car3 = 3
        }

    }
</code></pre>

<p>Controller:</p>

<pre><code> public class EnumController : Controller
    {
        // GET: Enum
        public ActionResult Index()
        {
            var model = new Test {MyCars = Test.Cars.Car3}; // set default value
            return View(model);
        }
        [HttpPost]
        public ActionResult Index(Test model)
        {
            .....
        }
    }
</code></pre>

<p>View:</p>

<pre><code>@Html.BeginForm()
{
&lt;div class="panel bg-white"&gt;
    &lt;div class="panel-header fg-white"&gt;
        Enums
    &lt;/div&gt;
    &lt;div class="panel-content"&gt;
        &lt;div class="input-control select size3"&gt;
            @Html.EnumDropDownListFor(model =&gt; model.MyCars)

        &lt;/div&gt;
    &lt;/div&gt;
    &lt;input type="submit" class="button success large" /&gt;
&lt;/div&gt;
}
</code></pre>


<p>In my view I have a <a href="http://www.asp.net/mvc/overview/releases/mvc51-release-notes#Enum">enumdropdownlist</a> (a new feature in Asp.Net MVC 5.1).</p>

<pre><code>@Html.EnumDropDownListFor(m =&gt; m.SelectedLicense,new { @class="form-control"})
</code></pre>

<p>If I execute the above code I get dropdownlist for my following enum.</p>

<pre><code>public enum LicenseTypes
{
    Trial = 0,
    Paid = 1
}
</code></pre>

<p>but by default I want my dropdownlist to have a value(custom text)
and this is what I tried</p>

<pre><code>@Html.EnumDropDownListFor(m =&gt; m.SelectedLicense,"Select a license" ,new { @class="form-control"})
</code></pre>

<p>but now the problem is when i run it, my dropdownlist looks like this
<img src="https://i.stack.imgur.com/lbtEQ.png" alt="enter image description here">
So, the default text I want to show doesn't appear by default.
If a user selects "select a license" and tries to submit the form, it does show an error saying "select a license" but it doesn't show as default text.
Something i need to change?</p>

<p>Ps: The image is the screenshot of the page when it loads. By default it'll show Trial as selected option.</p>


Html.EnumDropdownListFor: Showing a default text

在我看来，我有一个 ( Asp.Net MVC5.1中的一个新特性)。@Html.EnumDropDownListFor(m => m.SelectedLicense,new { @class="form-control"})如果我执行上面的代码，我会得到下面枚举的dropdownlist。public enum Li...

问Html.EnumDropdownListFor:显示默认文本
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