[英]Unable to determine the relationship represented by navigation property Entity Framework Core
[英]Unable to determine the relationship represented by navigation property to an Enum type entity
我有这个.Net Core 3.1 web 项目,它有一个实体( Process
)对 Enum 类型实体( Status
)的引用。 无状态工作流使用这种方式设置来处理程序中进程状态的变化。 在运行时,它在这一行失败并出现上述异常消息:
processes = await _dbContext.Process.ToListAsync();
完整的异常消息:
'Unable to determine the relationship represented by navigation property 'Process.Status' of type 'Status'.
Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.'
下面是 model 和 dbcontext 代码:
public enum StatusID : int
{
[Display(Name = "Draft")]
Draft = 1,
[Display(Name ="In Review")]
InReview = 2,
[Display(Name = "Approved")]
Inactive = 3
}
[Table("Status", Schema = "Industrial")]
public class Status
{
private Status() { }
[Key, DatabaseGenerated(DatabaseGeneratedOption.None)]
public StatusID StatusID { get; private set; }
[StringLength(50)]
public string Name { get; private set; }
}
[Table("Process", Schema = "Industrial")]
public partial class Process
{
[Key]
public int ProcessID { get; set; }
public StatusID StatusID { get; set; } = StatusID.Draft;
[ForeignKey("StatusID")]
public virtual Status Status { get; private set; }
}
public class DbContext
{
public DbSet<Process> Process { get; set; }
public DbSet<Status> Status { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Status>().HasNoKey().Property(c => c.StatusID)
.HasConversion(
v => v.ToString().ToLowerInvariant(),
v => (StatusID)Enum.Parse(typeof(StatusID), v, true)
)
.HasColumnName("GeneralName")
.IsUnicode(false);
}
}
我在这里搜索了其他帖子,许多人建议在 DbContext 的 OnModelCreating 方法中放置导航定义,我尝试了一些变体,都失败了。 这是我尝试过的一对:
modelBuilder.Entity<Process>()
.HasOne("Status", "Status")
.WithOne("Status");
modelBuilder.Entity<Process>()
.HasOne(p => p.Status)
.WithOne()
.HasForeignKey<Status>(m => m.StatusID)
.OnDelete(DeleteBehavior.Restrict);
我找到了这个问题的根本原因,是因为我的数据库表生成脚本在外键创建语句中有错误,应该如下:
ALTER TABLE [Industrial].[Process] WITH CHECK ADD CONSTRAINT [FK_Process_Status_StatusID] FOREIGN KEY([StatusID])
REFERENCES [Industrial].[Status] ([StatusID])
我所拥有的是[FK_Process_Status]
,而不是[FK_Process_Status_StatusID]
这是在 Microsoft SQL 服务器中。
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