blocks|key|1642625|text|Char不是实体框架的有效原语类型=实体框架不映射它。如果您检查CSDL+reference，您将看到有效类型的列表(char不在其中)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1642626|数据库char(1)翻译为string+(SQL+to+CSDL+translation)。Char被描述为non-unicode+string+with+fixed+length+1。|1642627|唯一难看的选项是使用字符串的第二个映射属性，而您的char非映射属性将只使用该属性中的string[0]。这只是EF中缺少一些简单的类型映射或转换器的另一个例子。|1642628|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/bb399548.aspx|1|http://msdn.microsoft.com/en-us/library/bb896344.aspx|2|https://stackoverflow.com/questions/6628881/what-are-valid-primitive-properties-in-entity-framework-code-first/6634829#6634829^0|0|4|1N|4|W|E|0|0|3|7|D|6|1A|4|L|N|1|1I|12|2|0|P|4|17|9|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@$9|10|A|11|1|12]]|E|$]]|$1|F|3|G|5|6|7|13|8|@$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@$9|1A|A|1B|1|1C]|$9|1D|A|1E|1|1F]]|E|$]]|$1|H|3|I|5|6|7|1G|8|@$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]|R|$5|M|N|O|E|$P|S]]|T|$5|M|N|O|E|$P|U]]]]

<code>Char</code> is not valid primitive type for entity framework = entity framework doesn't map it. If you check <a href="http://msdn.microsoft.com/en-us/library/bb399548.aspx" rel="noreferrer">CSDL reference</a> you will see list of valid types (<code>char</code> is not among them).

Database <code>char(1)</code> is translated as <code>string</code> (<a href="http://msdn.microsoft.com/en-us/library/bb896344.aspx" rel="noreferrer">SQL to CSDL translation</a>). <code>Char</code> is described as <a href="https://stackoverflow.com/questions/6628881/what-are-valid-primitive-properties-in-entity-framework-code-first/6634829#6634829">non-unicode string with fixed length 1</a>.

The only ugly option is second mapped property using string and your <code>char</code> non-mapped property will just use <code>string[0]</code> from that property. That is just another example how some simple type mapping or converters are damn missing in EF.

blocks|key|3542564|text|在Fluent+API中，您可以使用HasColumnType方法指定数据库列数据类型，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3542565|modelBuilder.Entity<Product>()+++
.Property(p+=>+p.Code)+++
.HasColumnType("char");|code-block|syntax|javascript|3542566|根据Andre+Artus‘s+answer+here的说法，HasColumnType在EF4.1中可用。|offset|length|3542567|对于那些使用数据注释的人来说，ColumnAttribute可以完成同样的事情。|3542568|[Column(TypeName="char")]
public+string+Code+{+get;+set;+}|3542569|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/5346155/ef-code-first-4-1-doesnt-support-nvarcharmax-at-all^0|0|0|N|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@$I|Z|J|10|1|11]]|A|$]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

In Fluent API you can specify the database column data type using the HasColumnType method like this:

<pre><code>modelBuilder.Entity&lt;Product&gt;() 
.Property(p =&gt; p.Code) 
.HasColumnType("char");
</code></pre>

According to Andre Artus' answer <a href="https://stackoverflow.com/questions/5346155/ef-code-first-4-1-doesnt-support-nvarcharmax-at-all">here</a>, HasColumnType is available in EF4.1.

For those using Data Annotations, the ColumnAttribute can accomplish the same thing.

<pre><code>[Column(TypeName="char")]
public string Code { get; set; }
</code></pre>

blocks|key|54047|text|[Column(+TypeName+=+"char(1)"+)]|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|54048|适用于我的EF+core+3.1.4|54049|entityMap^0|0|W|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|N|8|@]|D|@]|E|$]]]|I|$]]

<code>[Column( TypeName = &quot;char(1)&quot; )]</code>
works for me with EF core 3.1.4

blocks|key|3542600|text|我已经尝试了所有我想象的方法，我必须说，就我所知，公认的答案是解决char类型问题的唯一方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3542601|字符类型不能在EntityFramework中使用。|offset|length|style|BOLD|3542602|Fluent+API包含在此限制中。|3542603|如果你试图把一个字符放在Property(p+=>+p.MyCharProperty)上，会给你一个异常。|CODE|3542604|这意味着char属性不能用于Fluent+API，也不能用于属性。|3542605|最简单的解决方案是这样(由Ladislav+Mrnka提出)。|3542606|public+class+Product
{
++++public+char+Code+{+get;+set;+}

++++[Column("Code",+TypeName="char")]
++++[MaxLength(1)]
++++public+string+CodeString
++++{
+++++++++get+{+return+Code.ToString();+}
+++++++++set+{+Code+=+value[0];+}
++++}
}|code-block|syntax|javascript|3542607|需要注意的一点:你不能将私有、保护或内部属性放入。必须是公共。|3542608|流畅的API版本应该是这样的。|3542609|public+class+Product
{
++++public+char+Code+{+get;+set;+}

++++//We+need+the+property+but+we+will+use+the+Fluent+API+to+replace+the+attributes
++++public+string+CodeString
++++{
+++++++++get+{+return+Code.ToString();+}
+++++++++set+{+Code+=+value[0];+}
++++}
}|3542610|3542611|modelBuilder.Entity<Product>().Property(p+=>+p.Code)
++++.HasTypeName("char")
++++.HasMaxLength(1)|3542612|entityMap^0|0|0|2|0|0|8|11|1E|2|C|V|0|4|4|0|0|0|P|5|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|17|8|@$D|18|E|19|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1A|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1B|8|@$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]|$D|1G|E|1H|F|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|1I|8|@$D|1J|E|1K|F|G]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1L|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|1M|8|@]|9|@]|A|$T|U]]|$1|V|3|W|5|6|7|1N|8|@$D|1O|E|1P|F|G]]|9|@]|A|$]]|$1|X|3|Y|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|Z|3|10|5|S|7|1R|8|@]|9|@]|A|$T|U]]|$1|11|3|-4|5|6|7|1S|8|@]|9|@]|A|$]]|$1|12|3|13|5|S|7|1T|8|@]|9|@]|A|$T|U]]|$1|14|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]]|15|$]]

I have tried all the ways I have imagined and I must say the the accepted answer is the unique way to solve the problem of the char type as far as I know.

The char type isn't available for its use in EntityFramework.

Fluent API is included in this restriction.

If you try to put a char on the <code>Property(p =&gt; p.MyCharProperty)</code> will give you an Exception.

That means that char properties aren't available for Fluent API nor Attributes.

The easiest solution is this (as proposed by Ladislav Mrnka).

<pre><code>public class Product
{
 public char Code { get; set; }

 [Column("Code", TypeName="char")]
 [MaxLength(1)]
 public string CodeString
 {
 get { return Code.ToString(); }
 set { Code = value[0]; }
 }
}
</code></pre>

One note: you can't put the property private, protected or internal. Must be public.

Fluent API version would be like this.

<pre><code>public class Product
{
 public char Code { get; set; }

 //We need the property but we will use the Fluent API to replace the attributes
 public string CodeString
 {
 get { return Code.ToString(); }
 set { Code = value[0]; }
 }
}
</code></pre>

<hr>

<pre><code>modelBuilder.Entity&lt;Product&gt;().Property(p =&gt; p.Code)
 .HasTypeName("char")
 .HasMaxLength(1)
</code></pre>

blocks|key|54024|text|解决此问题的替代方法仅限于测试目的。使字段not+null到null暂时不能从设计模式使用。有时它会受到SQL+Management+Studio限制。(更改设置工具->选项->Designer+->表数据库设计器->取消选中“防止保存需要创建表的更改”|type|unstyled|depth|inlineStyleRanges|entityRanges|data|54025|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

There is alternate ways to tackle this issue for TESTING purpose only. Make the field not null to null able for time being from design mode. Sometime it is restricted SQL Management Studio. (Change setting Tools -> Option ->Designer -> Table Database designer -> Uncheck "Prevent saving changes that required table creation"

I have an object that has a char property:

<pre><code>public class Product
{
 public char Code
 {
 get;
 set;
 }
}
</code></pre>

Entity Framework doesn't seem to be able to map chars (this field is missing from the database when I create the database schema from my model objects). Is there anyway I can map the char (e.g. to a string) using the fluent API? I don't want to change the model objects as they are part of a legacy shared library.

How do I map a char property using the Entity Framework 4.1 "code only" fluent API?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个具有char属性的对象：public class Product{    public char Code    {        get;        set;    }}实体框架似乎不能映射字符(当我从模型对象创建数据库模式时，数据库中缺少此字段)。有没有什么办法可以使用fluent API来映射字符(例如，映射到字符串)？我不想更改模型对象，因为它们是遗留共享库的一部分。

问如何使用Entity Framework4.1“仅代码”流畅API映射char属性？
EN

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问如何使用Entity Framework4.1“仅代码”流畅API映射char属性？
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