实体框架代码优先 MaxLength 和 FixedLegth(char 与 varchar) [英] Entity Framework Code First MaxLength and FixedLegth (char vs varchar)

问题描述

我有一个从现有数据库创建的实体框架 CodeFirst 模型，我想使用 DataAnnotations 以不同的方式装饰一些 char 和 varchar.

I have an Entity Framework CodeFirst model that I'm creating from existing Database and I want to decorate some char and varchar in different way using DataAnnotations.

char 和 varchar 的区别在于 Char 的长度是固定的，而 varchar 的长度是可变的.

Difference between char and varchar is that the Char has fixed length and varchar have variable length.

对于 Varchar，我使用 [Maxlength(length)] 对于 char，这是正确的方法还是有更好的方法来定义类中的字符串属性在数据库中映射为 char?

For Varchar I'm using [Maxlength(length)] For char is this the correct way or there is a better way to define that the string property in the class is mapped as a char in the Database?

推荐答案

有了fluent api就可以使用IsFixedLength():

With the fluent api you can use IsFixedLength():

//Set StudentName column size to 50 and change datatype to nchar 
//IsFixedLength() change datatype from nvarchar to nchar
  modelBuilder.Entity<Student>()
                    .Property(p => p.StudentName)
                    .HasMaxLength(50).IsFixedLength();

使用注释，您可以指定类型:

With annotations, you can dictate the type:

[Column(TypeName = "char")]
[StringLength(2)]
public string MyCharField { get; set; }

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