blocks|key|548707|text|在构造函数中设置：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|548708|public+class+SearchModel
{
++++public+bool+IsMale+{+get;+set;+}
++++public+bool+IsFemale+{+get;+set;+}

++++public+SearchModel()
++++{+
++++++++IsMale+=+true;
++++++++IsFemale+=+true;
++++}
}|code-block|syntax|javascript|548709|然后在GET操作中将其传递给视图：|548710|[HttpGet]
public+ActionResult+Search()
{
++++return+new+View(new+SearchModel());
}|548711|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Set this in the constructor:

<pre><code>public class SearchModel
{
 public bool IsMale { get; set; }
 public bool IsFemale { get; set; }

 public SearchModel()
 { 
 IsMale = true;
 IsFemale = true;
 }
}
</code></pre>

Then pass it to the view in your GET action:

<pre><code>[HttpGet]
public ActionResult Search()
{
 return new View(new SearchModel());
}
</code></pre>

blocks|key|548726|text|你要点什么？你可能最终会得到一个默认搜索和一个从某个地方加载的搜索。Default+search需要一个默认的构造函数，所以就像之前建议的那样创建一个。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|548727|如果您从其他地方加载搜索条件，那么您可能应该有一些映射逻辑。|548728|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

What will you have? You'll probably end up with a default search and a search that you load from somewhere. Default search requires a default constructor, so make one like Dismissile has already suggested. 

If you load the search criteria from elsewhere, then you should probably have some mapping logic.

blocks|key|548775|text|使用以下构造函数代码为您的ViewModels创建一个基类，这些构造函数代码将在创建任何继承模型时应用DefaultValueAttributes。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|548776|public+abstract+class+BaseViewModel
{
++++protected+BaseViewModel()
++++{
++++++++//+apply+any+DefaultValueAttribute+settings+to+their+properties
++++++++var+propertyInfos+=+this.GetType().GetProperties();
++++++++foreach+(var+propertyInfo+in+propertyInfos)
++++++++{
++++++++++++var+attributes+=+propertyInfo.GetCustomAttributes(typeof(DefaultValueAttribute),+true);
++++++++++++if+(attributes.Any())
++++++++++++{
++++++++++++++++var+attribute+=+(DefaultValueAttribute)+attributes[0];
++++++++++++++++propertyInfo.SetValue(this,+attribute.Value,+null);
++++++++++++}
++++++++}
++++}
}|code-block|syntax|javascript|548777|并在您的ViewModels中继承以下内容：|548778|public+class+SearchModel+:+BaseViewModel
{
++++[DefaultValue(true)]
++++public+bool+IsMale+{+get;+set;+}
++++[DefaultValue(true)]
++++public+bool+IsFemale+{+get;+set;+}
}|548779|entityMap^0|D|A|1F|M|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

Create a base class for your <code>ViewModels</code> with the following constructor code which will apply the <code>DefaultValueAttributes</code>when any inheriting model is created.

<pre><code>public abstract class BaseViewModel
{
 protected BaseViewModel()
 {
 // apply any DefaultValueAttribute settings to their properties
 var propertyInfos = this.GetType().GetProperties();
 foreach (var propertyInfo in propertyInfos)
 {
 var attributes = propertyInfo.GetCustomAttributes(typeof(DefaultValueAttribute), true);
 if (attributes.Any())
 {
 var attribute = (DefaultValueAttribute) attributes[0];
 propertyInfo.SetValue(this, attribute.Value, null);
 }
 }
 }
}
</code></pre>

And inherit from this in your ViewModels:

<pre><code>public class SearchModel : BaseViewModel
{
 [DefaultValue(true)]
 public bool IsMale { get; set; }
 [DefaultValue(true)]
 public bool IsFemale { get; set; }
}
</code></pre>

blocks|key|765643|text|如果您需要将相同的模型发布到服务器，则在构造函数中具有默认bool值的解决方案对您来说是不可行的。让我们假设你有以下模型：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|765644|public+class+SearchModel
{
++++public+bool+IsMale+{+get;+set;+}

++++public+SearchModel()
++++{+
++++++++IsMale+=+true;
++++}
}|code-block|syntax|javascript|765645|在视图中，你会看到类似这样的东西：|765646|@Html.CheckBoxFor(n+=>+n.IsMale)|765647|问题是，当用户取消选中此复选框并将其发送到服务器时-您最终会在构造函数中设置默认值(在本例中为true)。|765648|因此，在这种情况下，我只需要在视图上指定默认值：|765649|@Html.CheckBoxFor(n+=>+n.IsMale,+new+{+@checked+=+"checked"+})|765650|entityMap^0|T|4|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|10|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|12|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|13|8|@]|D|@]|E|$]]|$1|S|3|T|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|U|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|V|$]]

In case you need to post the same model to server the solution with having default <code>bool</code> value in constructor would not be viable for you. Let's imagine that you have following model:

<pre><code>public class SearchModel
{
 public bool IsMale { get; set; }

 public SearchModel()
 { 
 IsMale = true;
 }
}
</code></pre>

On view you would have something like this:

<pre><code>@Html.CheckBoxFor(n =&gt; n.IsMale)
</code></pre>

The problem is when user uncheck this checkbox and post it to the server - you would end up with default value set up in constructor (which in this case is true).

So in this case I would end up with just specifying default value on view:

<pre><code>@Html.CheckBoxFor(n =&gt; n.IsMale, new { @checked = "checked" })
</code></pre>

blocks|key|548892|text|使用特定值：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|548893|[Display(Name+=+"Date")]
public+DateTime+EntryDate+{get;+set;}+=+DateTime.Now;//by+C#+v6|code-block|syntax|javascript|548894|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use specific value:

<pre><code>[Display(Name = "Date")]
public DateTime EntryDate {get; set;} = DateTime.Now;//by C# v6
</code></pre>

blocks|key|548926|text|<div+class="form-group">
++++++++++++++++++++<label+asp-for="Password"></label>
++++++++++++++++++++<input+asp-for="Password"++value="Pass@123"+readonly+class="form-control"+/>
++++++++++++++++++++<span+asp-validation-for="Password"+class="text-danger">
++++++++++++++++</div>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|548927|使用:+value="Pass@123“作为.net核心中输入的默认值|unstyled|548928|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>&lt;div class=&quot;form-group&quot;&gt;
 &lt;label asp-for=&quot;Password&quot;&gt;&lt;/label&gt;
 &lt;input asp-for=&quot;Password&quot; value=&quot;Pass@123&quot; readonly class=&quot;form-control&quot; /&gt;
 &lt;span asp-validation-for=&quot;Password&quot; class=&quot;text-danger&quot;&gt;&lt;/span&gt;
 &lt;/div&gt;
</code></pre>
use : value=&quot;Pass@123&quot; for default value in input in .net core

I have this model:

<pre><code>public class SearchModel
{
 [DefaultValue(true)]
 public bool IsMale { get; set; }
 [DefaultValue(true)]
 public bool IsFemale { get; set; }
}
</code></pre>

But based on my research and answers here, <code>DefaultValueAttribute</code> does not actually set a default value. But those answers were from 2008, Is there an attribute or a better way than using a private field to set these values to true when passed to the view?

Heres the view anyways:

<pre><code>@using (Html.BeginForm("Search", "Users", FormMethod.Get))
{
&lt;div&gt;
 @Html.LabelFor(m =&gt; Model.IsMale)
 @Html.CheckBoxFor(m =&gt; Model.IsMale)
 &lt;input type="submit" value="search"/&gt;
&lt;/div&gt;
}
</code></pre>

Default value in an asp.net mvc view model

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我有一个模型：public class SearchModel{    [DefaultValue(true)]    public bool IsMale { get; set; }    [DefaultValue(true)]    public bool IsFemale { get; set; }}但根据我在...

问asp.net mvc视图模型中的默认值
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