Code First 与父类别的一对多关系和类别

Question

public class Category
{
    [Key]
    public int CategoryId { get; set; }
    public int ParentCategoryId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public int Status { get; set; }
    public virtual ICollection<Category> ParentCategories { get; set; }
    public virtual ICollection<ImageSet> ImageSets { get; set; }

    [ForeignKey("ParentCategoryId")]
    public virtual Category ParentCategory { get; set; }
}    

public class ImageSet
{
    [Key]
    public int ImageSetId { get; set; }
    public int CategoryId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string InsertDate { get; set; }
    public int Status { get; set; }
    public virtual ICollection<Image> Images { get; set; }

    [ForeignKey("CategoryId")]
    public virtual Category Category { get; set; }
}

public class Image
{
    [Key]
    public int ImageId { get; set; }
    public int ImageSetId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string ImageUrl { get; set; }
    public string ThumbImageUrl { get; set; }
    public string InsertDate { get; set; }
    public int Status { get; set; }

    [ForeignKey("ImageSetId")]
    public virtual ImageSet ImageSet { get; set; }
}

Context:
    public DbSet<Category> Categories { get; set; }
    public DbSet<Image> Images { get; set; }
    public DbSet<ImageSet> ImageSets { get; set; }

错误页面：在表 'ImageSets' 上引入 FOREIGN KEY 约束 'FK_dbo.ImageSets_dbo.Categories_CategoryId' 可能 导致循环或多个级联路径。指定 ON DELETE NO ACTION 或 ON UPDATE NO ACTION，或修改其他 FOREIGN KEY 约束。可以 不创建约束。查看以前的错误。

有什么问题？

Answer 1

你需要添加这个：

modelBuilder.Entity<ImageSet>()
.HasRequired(is => is.Category)
.WithMany(c => c.ImageSets)
.WillCascadeOnDelete(false);

这里有很好的解释为什么会发生这种情况：

https://stackoverflow.com/a/19390016/1845408

https://stackoverflow.com/a/17127512/1845408