英文:
Failed executing DbCommand-Introducing FOREIGN KEY constraint
问题
Here's the translation of the code portion you provided:
以下是您提供的代码部分的翻译：
在进行dotnet-core迁移时，更新数据库时出现以下错误。
执行DbCommand失败（48毫秒）[参数 = []，CommandType = 'Text'，CommandTimeout = '30']
创建表[DepartmentSchool] (
[DepartmentID]唯一标识符 NOT NULL，
[SchoolsId]唯一标识符 NOT NULL，
[Id]唯一标识符 NOT NULL，
CONSTRAINT [PK_DepartmentSchool] PRIMARY KEY ([SchoolsId]，[DepartmentID]），
CONSTRAINT [FK_DepartmentSchool_Department_DepartmentID] FOREIGN KEY ([DepartmentID]）REFERENCES [Department]（[ID]）ON DELETE CASCADE，
CONSTRAINT [FK_DepartmentSchool_School_SchoolsId] FOREIGN KEY ([SchoolsId]）REFERENCES [School]（[ID]）ON DELETE CASCADE
);
以下是实体关系类：
**School**类（第一张表）：
```csharp
public partial class Schools
{
public Guid ID { get; set; }
public string Name { get; set; }
public Guid? CountryId { get; set; }
public Country Country { get; set; }
public ICollection<DepartmentSchool> DepartmentSchools { get; set; }
}
Department类（第二张表）：
public partial class Department
{
public Guid ID { get; set; }
public string Title { get; set; }
public DateTime CreatedAt { get; set; }
public ICollection<DepartmentSchool> DepartmentSchools { get; set; }
}
DepartmentSchool类（中间表）：
public class DepartmentSchool
{
public Guid Id { get; set; }
public Guid DepartmentID { get; set; }
public Department Department { get; set; }
public Guid SchoolsId { get; set; }
public Schools Schools { get; set; }
}
在模型生成器中，它的关系定义如下：
// School和Department之间的多对多关系
modelBuilder.Entity<DepartmentSchool>()
.HasKey(ds => new { ds.SchoolsId, ds.DepartmentID });
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Department)
.WithMany(d => d.DepartmentSchools)
.HasForeignKey(ds => ds.DepartmentID);
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Schools)
.WithMany(d => d.DepartmentSchools)
.HasForeignKey(ds => ds.SchoolsId);
这是您提供的代码的翻译。
英文:
Here showing following error when going to update-database, through dotnet-core migration.
Failed executing DbCommand (48ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
CREATE TABLE [DepartmentSchool] (
[DepartmentID] uniqueidentifier NOT NULL,
[SchoolsId] uniqueidentifier NOT NULL,
[Id] uniqueidentifier NOT NULL,
CONSTRAINT [PK_DepartmentSchool] PRIMARY KEY ([SchoolsId], [DepartmentID]),
CONSTRAINT [FK_DepartmentSchool_Department_DepartmentID] FOREIGN KEY ([DepartmentID]) REFERENCES [Department] ([ID]) ON DELETE CASCADE,
CONSTRAINT [FK_DepartmentSchool_School_SchoolsId] FOREIGN KEY ([SchoolsId]) REFERENCES [School] ([ID]) ON DELETE CASCADE
);
Below is the entity relation class are:
School Class(First Table):
public partial class Schools
{
public Guid ID { get; set; }
public string Name { get; set; }
public Guid? CountryId { get; set; }
public Country Country { get; set; }
public ICollection<DepartmentSchool> DepartmentSchools { get; set; }
}
Department Class(Second Table):
public partial class Department
{
public Guid ID { get; set; }
public string Title { get; set; }
public DateTime CreatedAt { get; set; }
public ICollection<DepartmentSchool> DepartmentSchools { get; set; }
}
DepartmentSchool Class (Middle table)
public class DepartmentSchool
{
public Guid Id { get; set; }
public Guid DepartmentID { get; set; }
public Department Department { get; set; }
public Guid SchoolsId { get; set; }
public Schools Schools { get; set; }
}
and in the modulbulider it is relation is define here:
//Many to many relationship between School and Depatment
modelBuilder.Entity<DepartmentSchool>()
.HasKey(ds => new { ds.SchoolsId, ds.DepartmentID });
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Department)
.WithMany(d => d.DepartmentSchools)
.HasForeignKey(ds => ds.DepartmentID);
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Schools)
.WithMany(d => d.DepartmentSchools)
.HasForeignKey(ds => ds.SchoolsId);
答案1
得分: 3
禁用级联删除，允许引用中的空值。
.OnDelete(DeleteBehavior.Restrict);
关于在Asp Core中的级联删除的更多信息，请参考关于级联删除的说明。
例如：
modelBuilder.Entity<Invoice>()
.HasOne(i => i.Customer)
.WithMany(c => c.Invoices)
.OnDelete(DeleteBehavior.Restrict);
有关错误原因的帮助链接，请查看错误原因的帮助链接。
英文:
Disable cascading delete by allowing null values in the references.
.OnDelete(DeleteBehavior.Restrict);
About Cascade Delete In Asp Core
For example:
modelBuilder.Entity<Invoice>()
.HasOne(i => i.Customer)
.WithMany(c => c.Invoices)
.OnDelete(DeleteBehavior.Restrict);
答案2
得分: 0
I added the code according to the accepted answer and it is working:
modelBuilder.Entity
.HasKey(ds => new { ds.SchoolsId, ds.DepartmentID });
modelBuilder.Entity
.HasOne(ds => ds.Department)
.WithMany(d => d.DepartmentSchools)
.OnDelete(DeleteBehavior.Restrict)
.HasForeignKey(ds => ds.DepartmentID);
modelBuilder.Entity
.HasOne(ds => ds.Schools)
.WithMany(d => d.DepartmentSchools)
.OnDelete(DeleteBehavior.Restrict)
.HasForeignKey(ds => ds.SchoolsId);
英文:
I added the code according to the accepted answer and it is working:
modelBuilder.Entity<DepartmentSchool>()
.HasKey(ds => new { ds.SchoolsId, ds.DepartmentID });
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Department)
.WithMany(d => d.DepartmentSchools)
.OnDelete(DeleteBehavior.Restrict)
.HasForeignKey(ds => ds.DepartmentID);
modelBuilder.Entity<DepartmentSchool>()
.HasOne(ds => ds.Schools)
.WithMany(d => d.DepartmentSchools)
.OnDelete(DeleteBehavior.Restrict)
.HasForeignKey(ds => ds.SchoolsId);
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