C# 在entity Framework Core中添加具有多个一对一关系且具有相同表的实体时出现堆栈溢出
在Entity Framework Core中添加具有多个一对一关系的实体时,我遇到了一个问题。基于这个问题,我有以下几点:C# 在entity Framework Core中添加具有多个一对一关系且具有相同表的实体时出现堆栈溢出,c#,entity-framework,asp.net-core,.net-core,entity-framework-core,C#,Entity Framework,Asp.net Core,.net Core,Entity Framework Core,在Entity Framework Core中添加具有多个一对一关系的实体时,我遇到了一个问题。基于这个问题,我有以下几点: public class Article { public int Id { get; set; } public int? PreviousId { get; set; } public Article Previous { get; set; } public int? NextId { get; set; } public A
public class Article
{
public int Id { get; set; }
public int? PreviousId { get; set; }
public Article Previous { get; set; }
public int? NextId { get; set; }
public Article Next { get; set; }
}
在DbContext
的OnModelCreating
中,如我所述:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.HasDefaultSchema("ab");
modelBuilder.ApplyConfiguration(new ArticleEntityTypeConfiguration());
}
public class ArticleEntityTypeConfiguration : IEntityTypeConfiguration<Article>
{
public void Configure(EntityTypeBuilder<Article> builder)
{
builder.ToTable("Articles");
builder.HasKey(table => table.Id);
builder.Property(table => table.Id).ValueGeneratedOnAdd();
builder.HasOne(table => table.Previous).WithOne().HasForeignKey<Article>(table => table.PreviousId);
builder.HasOne(table => table.Next).WithOne().HasForeignKey<Article>(table => table.NextId);
}
}
你知道我怎样才能避免那个错误吗?谢谢 如果添加新文章,则
PreviousId/NextId
应为空或现有article.Id
。如果您的article.Id增加,则PreviousId是现有记录的最大Id
以下是保存新文章的演示:
[HttpPost]
public async Task<IActionResult> Create(Article article)
{
if (ModelState.IsValid)
{
int minArticleId = _context.Articles.Max(a => a.Id);
var previous = await _context.Articles.Where(s => s.Id == minArticleId).FirstOrDefaultAsync();
article.PreviousId = minArticleId;
_context.Add(article);
await _context.SaveChangesAsync();
previous.NextId = article.Id;
_context.Update(previous);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
return View(article);
}
[HttpPost]
公共异步任务创建(文章)
{
if(ModelState.IsValid)
{
int minArticleId=\u context.Articles.Max(a=>a.Id);
var previous=await_context.Articles.Where(s=>s.Id==minArticleId.FirstOrDefaultAsync();
article.PreviousId=minArticleId;
_增加(第条);
wait_context.SaveChangesAsync();
previous.NextId=article.Id;
_更新(以前);
wait_context.SaveChangesAsync();
返回重定向到操作(名称(索引));
}
返回视图(文章);
}
所以我继续对此进行调查,并找到了帮助我解决问题的答案。诀窍是将DbContext
的OnModelCreating
更改为:
public void Configure(EntityTypeBuilder<Article> builder)
{
builder.ToTable("Articles");
builder.HasKey(table => table.Id);
builder.Property(table => table.Id).ValueGeneratedOnAdd();
builder
.HasOne(table => table.Previous)
.WithOne() // <-- one of this must be empty
.HasForeignKey<Article>(table => table.PreviousId)
.OnDelete(DeleteBehavior.Restrict);
builder
.HasOne(table => table.Next)
.WithOne(table => table.Previous)
.HasForeignKey<Article>(table => table.NextId);
}
public void配置(EntityTypeBuilder)
{
建筑商:可折叠(“物品”);
HasKey(table=>table.Id);
属性(table=>table.Id).ValueGeneratedOnAdd();
建设者
.HasOne(table=>table.Previous)
.WithOne()//表.PreviousId)
.OnDelete(DeleteBehavior.Restrict);
建设者
.HasOne(table=>table.Next)
.WithOne(table=>table.Previous)
.HasForeignKey(table=>table.NextId);
}
不确定这是否有用,但您尝试过吗?实际上导航不是这样的。存在多种线程,因此数据库中的min id不需要PreviousId。这就是为什么上一篇文章,或者至少上一篇文章id,必须是操作的输入。
public void Configure(EntityTypeBuilder<Article> builder)
{
builder.ToTable("Articles");
builder.HasKey(table => table.Id);
builder.Property(table => table.Id).ValueGeneratedOnAdd();
builder
.HasOne(table => table.Previous)
.WithOne() // <-- one of this must be empty
.HasForeignKey<Article>(table => table.PreviousId)
.OnDelete(DeleteBehavior.Restrict);
builder
.HasOne(table => table.Next)
.WithOne(table => table.Previous)
.HasForeignKey<Article>(table => table.NextId);
}