C# EF核心多对多关系标识插入错误
我遵循本指南在API中实现了多对多关系 当我试图创建一个新的项目条目,其中包含一个要保存到ProjectAreas链接表的区域列表(从预定义列表中选择),我得到以下错误:当identity\u insert设置为OFF时,无法在表“Area”中为identity列插入显式值。C# EF核心多对多关系标识插入错误,c#,entity-framework-core,C#,Entity Framework Core,我遵循本指南在API中实现了多对多关系 当我试图创建一个新的项目条目,其中包含一个要保存到ProjectAreas链接表的区域列表(从预定义列表中选择),我得到以下错误:当identity\u insert设置为OFF时,无法在表“Area”中为identity列插入显式值。 public class Project { [Key] [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public class Project
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long ProjectId { get; set; }
public string ProjectName { get; set; }
public string ProjectDescription { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public DateTime CreateDate { get; set; }
public User CreatingUser { get; set; }
public bool Closed { get; set; }
public User ClosingUser { get; set; }
public DateTime CloseDate { get; set; }
public Customer Customer { get; set; }
public ICollection<ProjectArea> ProjectAreas { get; set; }
public ICollection<ProjectCategory> ProjectCategories { get; set; }
}
有人能告诉我我缺少什么吗?将您的onmodel创建更改为以下内容:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ProjectArea>()
.HasKey(projectArea => new
{
projectArea.ProjectId,
projectArea.AreaId
});
modelBuilder.Entity<Project>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.ProjectId);
modelBuilder.Entity<Area>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.AreaId);
}
模型创建时受保护的覆盖无效(ModelBuilder ModelBuilder)
{
modelBuilder.Entity()
.HasKey(projectArea=>new
{
projectArea.projectd,
projectArea.AreaId
});
modelBuilder.Entity()
.HasMany(c=>c.ProjectArea)
.WithRequired()
.HasForeignKey(c=>c.projectd);
modelBuilder.Entity()
.HasMany(c=>c.ProjectArea)
.WithRequired()
.HasForeignKey(c=>c.AreaId);
}
将您的onmodel创建更改为此:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ProjectArea>()
.HasKey(projectArea => new
{
projectArea.ProjectId,
projectArea.AreaId
});
modelBuilder.Entity<Project>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.ProjectId);
modelBuilder.Entity<Area>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.AreaId);
}
模型创建时受保护的覆盖无效(ModelBuilder ModelBuilder)
{
modelBuilder.Entity()
.HasKey(projectArea=>new
{
projectArea.projectd,
projectArea.AreaId
});
modelBuilder.Entity()
.HasMany(c=>c.ProjectArea)
.WithRequired()
.HasForeignKey(c=>c.projectd);
modelBuilder.Entity()
.HasMany(c=>c.ProjectArea)
.WithRequired()
.HasForeignKey(c=>c.AreaId);
}
此错误表示您试图将值显式分配给数据库自动分配的列。此错误表示您试图将值显式分配给数据库自动分配的列。
public class DatabaseContext : DbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ProjectArea>().HasKey(projectArea => new { projectArea.ProjectId, projectArea.AreaId });
modelBuilder.Entity<ProjectArea>().HasOne(projectArea => projectArea.Project).WithMany(project => project.ProjectAreas).HasForeignKey(projectArea => projectArea.ProjectId);
modelBuilder.Entity<ProjectArea>().HasOne(projectArea => projectArea.Area).WithMany(area => area.ProjectAreas).HasForeignKey(projectArea => projectArea.AreaId);
}
public void Add(Project entity)
{
databaseContext.Project.Add(entity);
databaseContext.SaveChanges();
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ProjectArea>()
.HasKey(projectArea => new
{
projectArea.ProjectId,
projectArea.AreaId
});
modelBuilder.Entity<Project>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.ProjectId);
modelBuilder.Entity<Area>()
.HasMany(c => c.ProjectArea)
.WithRequired()
.HasForeignKey(c => c.AreaId);
}