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我有这个fellowing实体:使用实体框架4的实体和映射如何处理null(ICollection)?
public class Post
{
public long PostId { get; private set; }
public DateTime date { get; set; }
[Required]
public string Subject { get; set; }
public User User { get; set; }
public Category Category { get; set; }
[Required]
public string Body { get; set; }
public virtual ICollection<Tag> Tags { get; private set; }
public Post()
{
Category = new Category();
}
public void AttachTag(string name, User user)
{
if (Tags.Count(x => x.Name == name) == 0)
Tags.Add(new Tag {
Name = name,
User = user
});
else
throw new Exception("Tag with specified name is already attached to this post.");
}
public Tag DeleteTag(string name)
{
Tag tag = Tags.Single(x => x.Name == name);
Tags.Remove(tag);
return tag;
}
public bool HasTags()
{
return (Tags != null || Tags.Count > 0);
}
问题是与虚拟的ICollection标签{获得;私人设置; }
当里面没有标签时,它实际上显示为空。我无法初始化它,因为它需要是虚拟的。
如何处理实体中的空值?标签如何初始化以及在哪里?
谢谢。
你说得对,这是我的错。 – Rushino 2011-02-10 12:59:11