EF5删除实体

Question

如何使用EF5删除实体？我得到了这个错误：

The object cannot be deleted because it was not found in the ObjectStateManager.

当我尝试在我的DbSet上调用.Remove时。在谷歌搜索之后，我试过了

mycontext.Attach(entity)
mycontext.Remove(entity)

但通过这种方式，我得到了：

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

那么，它是不是在ObjectStateManager中？！:)

我的实体是这样的：

[Table("Words")]
public class Word : IWord
{
    [Key, Required]
    public int WordId { get; set; }

    [Required, StringLength(50)]
    public string Tag { get; set; }

    //Foreign Key
    public int VocabularyId { get; set; }

    //Navigation
    public virtual Vocabulary Vocabulary { get; set; }
    public virtual Language Language { get; set; }
    public virtual List<Translation> Translations { get; set; }

}

Answer 1

您可以考虑两种场景：

1.连接场景：您从数据库加载实体并将其标记为已删除

var word = ctx.Words.Where(a=>a.WordId == wordId).First();
ctx.DeleteObject(word);
ctx.SaveChanges();

2.断开连接场景：附加现有实体并将其标记为已删除

var word = new Word() { WordId = id };
ctx.Words.Attach(word);
ctx.DeleteObject(word);
ctx.SaveChanges();

第二种方法将帮助您避免不必要的数据库往返