我创建了一个非常简单的项目来演示每个层次结构的表继承。在我尝试生成数据库的单元测试中,根据配置,我得到了很多错误之一:
没有 Required()
方法
Map<InActiveUser>(x => x.Requires("IsActive").HasValue(false));
Map<ActiveUser>(x => x.Requires("IsActive").HasValue(true));
交付:
System.Data.DataException : An exception occurred while initializing the database. See the InnerException for details.
----> System.Data.EntityCommandCompilationException : An error occurred while preparing the command definition. See the inner exception for details.
----> System.Data.MappingException :
(6,10) : error 3032: Problem in mapping fragments starting at line 6:Condition member 'User.IsActive' with a condition other than 'IsNull=False' is mapped. Either remove the condition on User.IsActive or remove it from the mapping.
使用 Required()
方法:
Map<InActiveUser>(x => x.Requires("IsActive").HasValue(false).IsRequired());
Map<ActiveUser>(x => x.Requires("IsActive").HasValue(true).IsRequired());
交付:
System.Data.DataException : An exception occurred while initializing the database. See the InnerException for details.
----> System.Data.EntityCommandCompilationException : An error occurred while preparing the command definition. See the inner exception for details.
----> System.Data.MappingException :
(6,10) : error 3023: Problem in mapping fragments starting at lines 6, 13, 19:Column User.IsActive has no default value and is not nullable. A column value is required to store entity data.
据我了解,我们不应该在基本类型上定义鉴别器列/属性,但无论哪种方式,无论是否定义列似乎都没有区别:
public class User
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual int Id { get; set; }
[Required]
public virtual string Username { get; set; }
[Required]
[DefaultValue(true)]
public bool IsActive { get; set; } //have tried without this property
}
public class InActiveUser : User
{
public virtual DateTime DeActivatedDate { get; set; }
}
public class ActiveUser : User
{
}
最佳答案
您不能将鉴别器映射为实体中的属性。鉴别器定义实体的类型。原因很明确——鉴别器定义了实例类型。如果您能够在运行时更改鉴别器值,会发生什么情况? .NET 应该如何改变实例化对象的类型?
将实体定义为:
public class User
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual int Id { get; set; }
[Required]
public virtual string Username { get; set; }
}
public class InActiveUser : User
{
public virtual DateTime DeActivatedDate { get; set; }
}
public class ActiveUser : User
{ }
这应该有效:
modelBuilder.Entity<User>()
.Map<InActiveUser>(x => x.Requires("IsActive").HasValue(false))
.Map<ActiveUser>(x => x.Requires("IsActive").HasValue(true));
关于inheritance - EF4.1 Exception creating Database with table-per-hierarchy 继承,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6001198/