[英]Require One of Multiple Foreign Keys in Entity Framework
I'm basically trying to enforce this in Entity Framework: Require Only One Of Multiple Columns Be Not Null我基本上是想在实体框架中强制执行这一点: 只要求多列之一不是 Null
My database has several 1:m relationships where the child entity belongs to one of several parent entities.我的数据库有几个 1:m 关系,其中子实体属于几个父实体之一。 For example, let's say I have tables for Teachers
, Students
, and Guardians
.例如,假设我有Teachers
、 Students
和Guardians
的表格。 Each of those can have many PhoneNumbers
and EmailAddresses
.每个都可以有很多PhoneNumbers
和EmailAddresses
。 I am using EF Code First, and my models look something like:我使用的是 EF Code First,我的模型看起来像:
public class Teacher {
public int Id { get; set; }
public string Name { get; set; }
public List<PhoneNumber> PhoneNumbers { get; set; }
public List<EmailAddress> EmailAddresses { get; set; }
}
public class Student {
public int Id { get; set; }
public string Name { get; set; }
public List<PhoneNumber> PhoneNumbers { get; set; }
public List<EmailAddress> EmailAddresses { get; set; }
}
public class Guardian {
public int Id { get; set; }
public string Name { get; set; }
public List<PhoneNumber> PhoneNumbers { get; set; }
public List<EmailAddress> EmailAddresses { get; set; }
}
public class PhoneNumber {
public int Id { get; set; }
public string Number { get; set; }
}
public class EmailAddress {
public int Id { get; set; }
public string Email { get; set; }
}
When I run the migration, this creates the database with the tables/columns I would expect.当我运行迁移时,这会创建包含我期望的表/列的数据库。 The PhoneNumbers
and EmailAddresses
tables each have columns Teacher_Id
, Student_Id
, and Guardian_Id
, which are foreign keys to their respective parent entity. PhoneNumbers
和EmailAddresses
表各有列Teacher_Id
、 Student_Id
和Guardian_Id
,它们是各自父实体的外键。 However, there are no constraints on how many parent entities can be set on the child.但是,对子实体可以设置多少父实体没有限制。 For example, I can create a PhoneNumber
that has all three parent IDs set to null, or I can set both a Teacher_Id
and a Guardian_Id
.例如,我可以创建一个PhoneNumber
,将所有三个父 ID 都设置为 null,或者我可以同时设置Teacher_Id
和Guardian_Id
。
I tried adding a required attribute to the parents like so:我尝试像这样向父母添加必需的属性:
public class Teacher { // Also Student/Guardian
public int Id { get; set; }
public string Name { get; set; }
[Required]
public List<PhoneNumber> PhoneNumbers { get; set; }
[Required]
public List<EmailAddress> EmailAddresses { get; set; }
}
That does not seem to have any effect.这似乎没有任何效果。
I think there is no way to do this on entities.我认为没有办法对实体执行此操作。 Instead, create a migration and try to alter the table in migration class like this:相反,创建一个迁移并尝试更改迁移 class 中的表,如下所示:
public partial class YourMigrationName: Migration
{
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.Sql("ALTER TABLE [dbo].[PhoneNumber]
WITH CHECK ADD CONSTRAINT [CK_PhoneNumer_Teacher_Student_Guardian] CHECK (Teacher_Id
is not null or Student_Id is not null or Guardian_Id is not null)
GO
ALTER TABLE [dbo].[EmailAddress] WITH CHECK ADD CONSTRAINT
[CK_EmailAddress_Teacher_Student_Guardian] CHECK (Teacher_Id is not null or
Student_Id is not null or Guardian_Id is not null)
");
}
}
Try this:尝试这个:
public class PhoneNumber
{
public int Id { get; set; }
public string Number { get; set; }
//Added this code:
[Required]
public Teacher Teacher { get; set;}
}
public class EmailAddress {
public int Id { get; set; }
public string Email { get; set; }
//Added this code:
[Required]
public Teacher Teacher { get; set;}
}
That would make sure you cannot create PhoneNumber without Teacher.这将确保您无法在没有教师的情况下创建电话号码。 You can also do this:你也可以这样做:
public class PhoneNumber
{
public int Id { get; set; }
public string Number { get; set; }
public int TeacherId
public Teacher Teacher { get; set;}
}
That would also detect that you want to add constraint on your PhoneNumber.这也将检测到您想在您的电话号码上添加约束。 Both ways work fine.两种方式都可以正常工作。
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